Proceedings

of the Tomsk Technological Institute

of Emperor Nicholas II

Vol. 18. 1910. No. 2.

IV.

Ya. I. Nikolin.

Destruction, Disinfection, and Utilization of Slaughterhouse Wastes.

With 16 plates of drawings.

I–VIII, 1–96.

PREFACE.

The science bearing the name of Sanitary Engineering, in the precise sense of the word, ought to embrace and bring within the scope of its consideration every possible application of engineering to the cause of ensuring the health of the population. In view of the multitude and variety of such applications, Sanitary Engineering, in the broad and proper meaning of this word, covers a very extensive field of technical science and includes a whole series of technical doctrines that developed more or less independently and only in recent times have come to recognize their mutual connection and their conceptual unity.

One of the major branches of Sanitary Engineering, if its subdivisions are classified according to the objects upon which engineering acts, is the branch of the assainissement of the soil.

This branch, which has developed as an independent science under the name of Sewerage of Cities, in the present state of engineering, in its essence, goes beyond the limits of the traditional name. The point is that at the present time, within the limits of this science, one must consider not only the removal of the liquid wastes of urban life, but also the purification of these liquid wastes, as well as the removal of solid wastes, the rendering harmless of these solid wastes by their destruction or utilization, the destruction and utilization of animal carcasses, and the cremation of human corpses. Since these necessary technical elements are now included in courses on Sewerage, it would seem timely to change the traditional name and, following the example of foreign terminology (Städtereinigung, Assainissement des villes), to adopt for this branch of Sanitary Engineering a new name—Assainissement—or, at least, Sewerage and Assainissement—of cities.

As indicated above, the task of the assainissement of cities is divided into three principal parts: first—the matter of sewerage, i.e. the removal of liquid wastes; second—the matter of sewage purification, i.e. the rendering harmless of those same liquid wastes; and third, finally, the removal and rendering harmless of solid wastes.

This last element of urban sanitation constitutes one of the important and, moreover, very difficult tasks of municipal management.

The necessity of removing and rendering harmless solid refuse, especially animal remains and corpses, was recognized by civilized peoples thousands of years before our time. Other elements of urban sanitation—sewerage and, in part, the purification of wastewater—already in remote antiquity received not only wide application but also a sufficiently satisfactory technical formulation. Meanwhile, the removal and especially the rendering harmless of solid refuse over the course of millennia were, and to a significant extent continue to be, very imperfect from a technical point of view, as well as unsatisfactory from a sanitary point of view and prohibitively expensive from an economic point of view. Only in recent decades has the possibility appeared of a more or less satisfactory solution to this difficult problem of municipal management, thanks to the application to this field of special inventions of modern technology.

The application of the newest technical methods makes it possible not only to render harmless or destroy solid refuse of various kinds, but at the same time to utilize it in a more or less complete and perfected manner. Such utilization of refuse, combined with its rendering harmless, fully or partly repays the expenses of organizing the enterprise, and under favorable conditions may even bring in a considerable income.

Only thanks to the introduction of such utilization does the difficult task of removing and rendering harmless solid refuse receive a real solution, since by this means the most important obstacle is eliminated—the economic burden and unproductiveness of organizing the enterprise. Thus, to modern technology has fallen the honor of solving this difficult question not only from the technical and sanitary, but also from the economic point of view.

But the fruitful work of technology in this field, of course, must not stop at the first steps. The entire future of the matter of removing and rendering harmless solid refuse depends on technical improvements that will make it possible to increase the productivity of methods for utilizing refuse and thereby to expand the range of their application. It is a direct duty of Sanitary Engineering, as the science responsible for this field of technical knowledge, to help, as far as possible, the technical progress of methods for rendering harmless and utilizing solid refuse, and to disseminate information on this matter with a view to a wider application of existing methods. For the fulfill—

...of the first task, Sanitary Engineering must devote serious attention to the questions of rendering harmless and utilizing solid refuse, corresponding to the importance of this matter for the sanitary improvement and technical economy of populated places. To accomplish the second task, Sanitary Engineering must take the path of popularizing the questions related to this matter among municipal-economy workers and in broad circles of the population.

Among the various urban institutions requiring the special attention of Sanitary Engineering, slaughterhouses occupy one of the foremost places. The purpose of their work—the supply of food products—compels an irreproachable organization of the matter in sanitary respects. Meanwhile, in view of the peculiarities of production, in view of the inevitability of a large quantity of remnants and refuse of every kind, in view of the specific properties of these remnants and refuse, and finally in view of the centralization and mass character of production, which grows rapidly as populated places grow, the strict provision of sanitary improvement in slaughterhouses is a difficult and complex technical task. All details of the internal arrangement, all details of the equipment of slaughterhouses must be expediently conceived and most carefully adapted to the irreproachable, from the sanitary standpoint, execution of the work. Therefore all elements of the internal arrangement, and especially the equipment of slaughterhouses, deserve the serious attention of Sanitary Engineering.

The most serious task of Sanitary Engineering in the matter of slaughterhouse equipment is the question of the removal and rendering harmless of a range of refuse produced as a result of slaughter.

From the point of view of removing this refuse, one must distinguish between liquid and solid refuse. The question of removing and rendering harmless liquid refuse is resolved satisfactorily from both the technical and the economic point of view by arranging an appropriate system of water supply and sewerage, with the use of purification devices. The situation is far less favorable with the removal and rendering harmless of solid refuse. The primitive methods of carting away and destruction that have long been used and remain widespread to the present time are far from reliable from the sanitary point of view and, moreover, are associated with large unproductive expenditures.

These methods, when applied to the refuse of slaughterhouses, are doubly disadvantageous, since among this refuse there occur, in considerable quantity, elements that can acquire substantial value under rational utilization. The latter circumstance...

IV.                             Ya. I. Nikitin.

...tendency manifests itself especially sharply in application to one part of slaughterhouse waste—to the so-called confiscates. By this name are meant whole carcasses of animals, or parts of them, declared by veterinary supervision to be unfit for consumption as food. It is self-evident that confiscates constitute a valuable material for utilization, and that their fruitless destruction, connected moreover with certain expenses, is extremely undesirable. If the destruction of such valuable material has taken place, and does take place, then it is solely owing either to the inability, or to ignorance, of methods of rendering harmless connected with utilization. Hence that fact becomes understandable: when technology finally found a path toward resolving the question of rendering solid wastes harmless in general through applying utilization to them, the objects of the first experiments and the first methods of utilization became slaughterhouse wastes in general and confiscates in particular.

There is, however, another sphere in which the application of rendering harmless jointly with utilization found a place at the same time, in approximately the same forms and for the very same reason. I am speaking of the carcasses of animals that have fallen or been killed on suspicion of a contagious disease. They were, and in part remain to the present time, the objects of special industrial establishments belonging to private individuals, which bear the name of knackeries, or, in common speech, rendering yards. These establishments engage in the utilization of animal carcasses, and also of part of the confiscates acquired from slaughterhouses, by means of more or less primitive methods, usually insufficiently productive from a technical standpoint and often impermissible from a sanitary standpoint.

This latter circumstance in particular long ago attracted the attention of cities, while the undoubted productivity of the material for utilization at once provided ground for the first applications of newly invented technical methods of processing. Hence arose the idea, put into practice by many municipal administrations, of utilizing, together with rendering harmless, both animal carcasses and confiscates by means of properly arranged and equipped institutions belonging to the city. Since, further, between confiscates and animal carcasses there has never been any real boundary, the new methods of their processing are one and the same and, moreover, such as may be considered entirely safe from the sanitary standpoint; and since the centralization, around slaughterhouses, of all auxiliary industries connected with them is an advantageous matter, it proves convenient to attach those municipal institutions which replaced the old knackeries to the municipal slaughterhouses.

Destruction and Utilization of Slaughterhouse Waste.

These establishments, together with the analogous installations existing at slaughterhouses, intended for the disinfection and utilization of solid (chiefly) wastes of other kinds, constitute what is called a utilization plant.

From all that has preceded it is clear that the establishment of utilization plants opens a new era in the matter of destroying solid slaughterhouse wastes. In addition to the unquestionable achievement of sanitary aims through the use of technically perfected installations, utilization plants are institutions that pay for the costs of their own construction and operation, and often even yield a net income; in the worst case they require modest subsidies, insignificant in comparison with the sanitary benefit they bring.

There is no need to speak of the importance of such institutions for cities. One can only repeat the wish that Sanitary Engineering, on the one hand, by further improving and cheapening production, should make utilization plants accessible to small populated places, and, on the other, by publishing information about institutions of this kind, should make it possible for the officials of municipal administrations to become acquainted with the aims, advantages, methods of construction, and equipment of these institutions.

Unfortunately, the application of the newest methods of disinfecting slaughterhouse wastes, and in particular the construction of properly organized utilization plants, is not yet very common even abroad, and is encountered still more rarely among us. The spread of these institutions, as well as the desirable popularization of information about them in broad circles, is hindered, among other things, by the extreme scarcity of technical literature on this special question, both abroad and in our country. In our book literature, for example, as far as I know, only a few brochures are devoted to this question, belonging to Messrs. Voevodsky, Neitstube, and Belov. Moreover, some of them are already bibliographical rarities, so that I have not yet succeeded in obtaining them. It therefore seems to me that every step toward disseminating information about modern, more perfected methods of disinfection and utilization of slaughterhouse wastes, and about cases of their application in practice, is useful. This consideration prompted me, having become interested in the matter of the destruction and utilization of wastes for a particular and accidental reason, to devote some time to studying this question in general and as applied to one useful undertaking on Russian soil, and to publish the result of my work in print in the form of the present article.

Its origin is as follows.

While engaged in certain questions of sewerage, including questions of wastewater purification, in 1906 I visited the city of Odessa twice, in April and in September, chiefly for the purpose of studying the local irrigation fields. Meanwhile, on these same irrigation fields, next to the pumping station for sewage, there is located the municipal utilization plant. I took the opportunity to acquaint myself with it in detail and to collect a number of data on the methods employed there for the utilization of slaughterhouse confiscates and animal carcasses. I intended to publish this material as part of a work concerning the irrigation fields of Odessa in general. But certain circumstances compelled me to postpone publication of this latter work, since the proposal arose to include it, as a constituent part, in a more extensive study of the agronomic method of wastewater purification in general and its application in Russia. Since the sections of the article relating to the utilization plant were not in direct and inseparable connection with its remaining parts, I ultimately considered it more convenient to publish them separately.

Having become interested in the question of rendering harmless and utilizing slaughterhouse wastes in general, I, while processing the material relating to the Odessa plant, acquainted myself with a considerable portion of the literature on this question. I was also prompted to such study by the wish to include consideration of this question in the course on Sanitary Engineering that I teach at the Tomsk Technological Institute. Thus I collected a number of general data on the question of rendering harmless and utilizing slaughterhouse wastes. This gave me occasion to broaden my original intentions and to make an attempt to provide a small monograph on the given question, to which the description of the Odessa utilization plant relates as a useful illustration and a living practical example.

At the same time I must make the reservation that, despite the measures taken and the long wait, I was unable to obtain some sources known to me by title, as well as technical data on the construction and equipment of certain utilization plants existing in Russia. This circumstance deprived me of the possibility, in the present article, of setting out the question with greater completeness.

I think, however, that even in its present composition the proposed article will give persons interested in the matter not a few new

and useful information. Since my collection of the missing sources is continuing, I have grounds to expect, when the present monograph is published as a separate book, to provide more exhaustive material. With this in view, I would also ask persons who can assist me by supplying materials and information, as well as by offering their guidance and comments on the question that interests me, to send them to the following address: Tomsk, Technological Institute.

The material for the present article, in addition to printed sources, consisted of technical and other data collected by me in 1906 in the city of Odessa with the kind assistance of the manager of the Odessa utilization plant, I. A. Nonevich, to whom I consider it my duty to express my profound gratitude.

I. Residues and refuse of slaughterhouses and objects of raw-product establishments.

The operation of slaughterhouses, at the scale which it has reached in large cities, and which continues to develop with the unrestrained growth of modern cities, while presenting many benefits for the population, at the same time gives rise to a whole series of inconveniences that compel one to reflect upon it.

The following figures, concerning the number of animals slaughtered annually in several German cities (the figures refer to 1902–3), may give an idea of the scale of work in this branch of industry:

No. in order	Cities	Large livestock, head	Small livestock, head	Total, head
1	Augsburg	13142	64137	77279
2	Berlin	155539	1544848	1700387
3	Breslau	26311	205661	231972
4	Halle	10152	81606	91758
5	Hamburg	58568	423537	482105
6	Dresden	34433	304715	339148
7	Düsseldorf	24676	112423	137099
8	Cologne	33267	186012	219279
9	Leipzig	33354	288798	322152
10	Munich	74716	465538	540254
11	Nuremberg	25214	186194	211408

Such a scale of work of urban slaughterhouses, with a sharply expressed factory-like character, yields a whole series of residues and refuse, which require attention both on account of their specific qualities and especially on account of their quantity, and, when they arrive in mass, create an extremely unpleasant and difficult task in their cleaning up, removal, destruction or processing—in a word, rendering harmless. This task urgently demands resolution, since the inconveniences arising from negligent or improper han—

…of removal, are not usually confined to the limits of the slaughterhouses themselves or their immediate neighborhood, but often spread much more widely, exerting an influence over a considerable area of the surroundings, even over whole parts of cities, and arousing the legitimate dissatisfaction of the inhabitants.

In devoting the present article specifically to the question of the proper solution of the problem of rendering harmless the refuse of slaughterhouses, we must first of all determine what is meant by this name.

To slaughter remnants, in the broad sense of the word, belong all those remains of animal carcasses which, wholly or in part, have no use in the meat industry. These include: blood, the contents of the stomach and intestines, intestines, hides, wool, bristles, bones, horns, hooves, fat, as well as animal organs not used for food, and animal carcasses or parts thereof deemed suspect at veterinary inspection.

In turn, these elements are divided into three smaller groups: 1) slaughter remnants in the special sense of the word—substances not belonging to meat products, but having independent industrial value and subject to industrial processing; such are hides, wool, bones, hooves, etc.; 2) slaughterhouse refuse—substances likewise not belonging to meat products, but having no industrial value and requiring rendering harmless by means of removal or destruction (even if industrial processing is applied for purposes of utilization); such are the contents of the intestines, intestinal mucus, organs not used for food, blood (although the latter is sometimes subjected to industrial processing and then may be assigned to the preceding category); 3) confiscates—meat products that have lost industrial value owing to their being suspect in a sanitary respect and that, like refuse, are subject to rendering harmless by destruction or utilization.

All these remnants and refuse of slaughterhouses have the unpleasant property that they either by themselves pass extremely readily into putrefaction, accompanied by a heavy odor, or are to a greater or lesser degree contaminated with organic substances that easily decay. Moreover, they create another danger for the inhabitants of districts adjacent to slaughterhouses in the form of wastewater, which carries with it particles of animal refuse, blood, dirt, meat, fat and, with such contents, likewise readily passes into decomposition.

The problem that arises before the public administration or the administration of slaughterhouses, with a view to ensuring sanitary well-…

...of the sanitary condition of the city and the interests of the inhabitants of the nearest district consists in ensuring, by means of appropriate, reliable measures, that the above-mentioned substances are prevented from the easily occurring decay at the place of production.

This task of rendering residues and wastes harmless is carried out in three ways: by removal (with subsequent natural destruction), by artificial destruction on site, or by industrial processing. The choice of the methods applied for rendering them harmless depends on the physical condition, quality, industrial value, and especially the quantity of residues and wastes, as well as on the technical and economic resources available to the slaughterhouses.

Thus, slaughter residues that have industrial value are removed by being transferred for processing elsewhere or within the slaughterhouses themselves. Owing to the mass character of the work of modern slaughterhouses, it proves substantially advantageous to process slaughter residues at the place where they are obtained, and the newest methods of processing make it possible to carry this out under conditions irreproachable from the sanitary point of view. As a result, at the present time it is becoming common for the slaughterhouses themselves to have a number of auxiliary productions for processing slaughter residues.

Liquid wastes from slaughterhouses are removed by means of sewerage; their rendering harmless is carried out either by the natural process after discharge into watercourses, or by the application of artificial purification methods, or, finally, by utilization through irrigation fields.

The rendering harmless of confiscated materials is carried out either by removal and destruction outside the slaughterhouses (burial), or by destruction on site (burning), or, finally, by industrial processing. In view of the undoubted industrial value of confiscated materials, there has always been a tendency to utilize them. But sanitary considerations have always excluded the utilization of a significant part of the confiscated materials most suspect from the standpoint of infection. Since, moreover, insufficiently perfected methods of utilization are inadmissible within slaughterhouses and, in general, within inhabited places, the utilization of confiscated materials by primitive methods is carried out together with the utilization of the carcasses of fallen animals in special institutions of a private character, the so-called rendering establishments or knackeries. At the present time, technology possesses methods for treating confiscated materials and carcasses that make it possible to utilize them...

in their entirety, regardless of their sanitary properties, and moreover in such a way that the conduct of production is permissible within populated areas and at the slaughterhouses themselves. Under these conditions it becomes possible and advantageous, for economic reasons, to concentrate the utilization of these elements also at the slaughterhouses, in the form of a special auxiliary production.

The rendering harmless of the solid wastes of slaughterhouses is a question of serious difficulty. By their qualities these elements, having no industrial value and being of little use for utilization, are therefore widely dealt with by the method of removal. But, with the rapid growth in the size of slaughterhouses, the expenses for removing solid wastes become extremely burdensome. Moreover, these wastes in any case contain a considerable quantity of substances having value for agriculture, the use of which is paralyzed by the burden of useless admixtures. Therefore, with regard to solid wastes as well, modern technology introduces more perfect methods of utilization which, even if they do not fully pay for themselves, at least reduce the costs of removal and the senseless loss of the valuable part of the wastes.

From the foregoing it is evident that the problem of rendering harmless the residues and wastes of slaughterhouses is solved, with respect to all their kinds, in the best manner by rational utilization, and technology provides and seeks methods for the most correct solution of the problem in this direction.

The present article will be devoted chiefly to the exposition of new technical methods of rendering harmless, by means of destruction and utilization, as applied to the solid wastes of slaughterhouses, including confiscated products and animal carcasses.

II. Quantity of residues and wastes of slaughterhouses.

The weight of the residues and wastes of slaughter may be considered approximately as corresponding to the difference between the live weight of the animal and the weight of its carcass. This weight may generally be taken as the weight of all substances subject to removal, destruction, or processing.

Since the live weight of animals fluctuates depending on breed, age, and condition, as does the carcass weight, the total weight of the residues and wastes is likewise subject to fluctuations. For example, for cattle the difference between live weight and carcass weight varies between 40 and 65%, for sheep between 45 and 65%, and for pigs between 15 and 25%.

To determine the quantity of waste by kind of animal, one must become acquainted with the average standards for live weight and carcass weight.

On the basis of a series of observations at the Leipzig slaughterhouses, the following data have been obtained in this regard.

Average weights of live livestock:

Animal	Weight
bulls	695.81 kilograms
oxen	647.93 kilograms
cows	560.01 kilograms
young cattle	468.55 kilograms
calves	69.58 kilograms
sheep	53.58 kilograms
pigs	107.30 kilograms

Average weights in carcasses:

Animal	Weight
bulls	374.55 kilograms
oxen	365.96 kilograms
cows	277.79 kilograms
young cattle	253.80 kilograms
calves	44.01 kilograms
sheep	29.11 kilograms
pigs	89.89 kilograms

Comparing these average figures, one may establish the following average ratios of carcass weight and of the weight of residues and waste to live weight, in %:

Animal	Carcass weight	Residues and waste
bulls	54%	46%
oxen	56%	44%
cows	50%	50%
young cattle	54%	46%
calves	63%	37%
sheep	54%	46%
pigs	84%	16%

These percentage averages, when applied to waste, cannot be considered entirely exact, but in any case they can provide a basis for an approximate determination of the quantity of these elements according to the turnover of a slaughterhouse. They cannot be considered exact, among other reasons, because in determining carcass weight a number of parts that are meat products are excluded (legs, parts of the head, etc.), and, conversely, some are included which in the end may prove to be among the objects of processing.

It is considerably more difficult to determine the weights of the separate kinds of residues and waste, in order to have data when designing slaughter—

are useless for determining the turnover of their by-products. However, in the literature there are attempts to establish these data as well.

Thus, according to Ostertag, bones constitute, in lean cattle, \(1/8\), and in very well-fattened cattle only \(1/14\) of the weight of the body, i.e. on average about 10%. According to the data of the German Agricultural Society, the weight of bones amounts to from 15.1 to 15.4% of the weight of the carcass for cattle.

According to the same data, the average weight of the hide is 7–8% of the live weight and 11.1–12.7% of the weight in the carcass.

The average weight of fat and tallow is calculated as 12.4–16.55% of the weight in the carcass.

According to Wolf, the weights of the contents of the stomach and intestines, as well as of the empty stomach and intestines, are represented in the following percentage ratios to live weight.

A. Cattle:

Item	Percentage of live weight
Contents of the stomach and intestines	12–18%
Empty stomach	2.7–4.5%
Empty intestines	1.4–2%
Total	16.1–24.5%

B. Small ruminants:

Item	Percentage of live weight
Contents	7.0%
Stomach	1.2%
Intestines	2.4%
Total	10.6%

C. Swine:

Item	Percentage of live weight
Contents	5–7%
Stomach	0.7–1.2%
Intestines	2.2–3.9%
Total	7.9–12.1%

According to Geissler, the quantity of flowing blood in relation to live weight amounts to:

Animal	Percentage of live weight
for cattle	4.02–5.75%
for small ruminants	4.40–6.65%
for sheep	4.37–7.56%
for swine	1.45–5.74%

If an attempt is made to calculate, on the basis of the above and other considerations, the total quantity of slaughter residues and offal per head of cattle with a live weight of 625 kilograms, then the following figures may be accepted:

No.	Item	Weight
1.	Bones	62.50 kilograms
2.	Hide	47.35 “
3.	Tallow and fat	32.50 “
4.	Contents of the stomach and intestines	93.75 “
5.	Intestines	10.60 “
6.	Blood	35.95 “
7.	Other refuse	44.00 “
	Total	326.65 kilograms

According to this calculation, the quantity of remains and refuse reaches 52.3% of the live weight, and only 47.7% falls to the useful weight of the carcass. Meanwhile, if, in accordance with the foregoing, one takes as the weight of the remains and refuse the difference between the live weight and the carcass weight, then in the present case we must take 46%, or approximately 287 kilograms. The difference of 6.3% is explained by the fact that the weight of the carcass includes the weight of the bones of the head, approximately 40 kilograms. Since this amount, when the head is put up for sale, is not and cannot be sent for processing into meat, the difference between the live weight and the carcass weight may be taken as the weight of the remains and refuse of slaughterhouses when designing and calculating the auxiliary operations attached to them.

III. Processing of Slaughterhouse Remains.

(General concepts).

The subject of the present article is the actual utilization of slaughterhouse refuse.

But, having touched earlier upon the question of the remains of slaughter, it seems to me not without interest to give the most general notions concerning the kinds of operations that have arisen on the basis of processing these remains. This is of all the greater interest because the more or less varied operations of this kind in our time are concentrated around the slaughterhouses themselves. Therefore, for a complete conception of the technical scope of a modern, widely developed slaughterhouse, a general notion of the composition of these auxiliary enterprises is by no means superfluous for persons specially interested in the question. With these aims in mind, I consider it possible to devote the present section to a list of the auxiliary operations at slaughterhouses in general, both for the processing of remains and for the utilization of refuse, and then to present certain considerations concerning their connection with slaughterhouses, as well as concerning their features and subdivision from the technical and sanitary point of view.

Of the ancillary industries connected with slaughterhouses by the commonality of the material processed, and not infrequently, in recent times, increasingly grouped on the territory of slaughterhouses, the following types may be enumerated:

1) for the processing of blood;
2) for the treatment of intestines;
3) for the utilization of the contents of the stomach and intestines;
4) for the treatment of hides;
5) for obtaining glue;
6) for obtaining tallow;
7) for the manufacture of margarine;
8) for obtaining fatty acids;
9) for making soap;
10) for obtaining glycerin;
11) for processing bones;
12) for treating hair and bristles;
13) for cooking and sterilizing meat.

If to this one adds the installations for the destruction of refuse, for the utilization of refuse, confiscated material, and animal carcasses, and if one notes at the same time that each of the types listed above is subdivided into varieties, then it is not difficult to see that a modern, well-developed slaughterhouse represents an entire technical world, a world of the most varied and interesting industries.

All industries dealing with slaughterhouse residues and refuse—which are briefly called ancillary industries at slaughterhouses—are at present usually grouped around the slaughterhouse itself. This is a natural consequence of the rapid development of slaughterhouses, corresponding to the rapid growth of the population, owing to which the quantity of slaughter residues and refuse reaches such a magnitude that they can be processed on the spot in specially equipped establishments. Local conditions also often compel processing to be carried out in direct connection with the slaughterhouse, without which economic success in this treatment cannot be achieved.

At first glance it might seem surprising that, in the form of ancillary industries at slaughterhouses, there has appeared a series of such establishments which, according to prevailing opinion and old traditions, people are accustomed to seeing arranged separately. Nevertheless, constant technical improvements in production and the constant striving of the enterprise toward economic success are ready to erase completely the traditional boundary between them and the slaughterhouse. Uninterrupted—

convinced and familiar with the technique of these industries, the observer no longer stops before the combination of these establishments—seemingly unconnectable by their internal characteristics—and regards this combination as a pledge of economic success.

The only division between the separate establishments and the slaughterhouse is now merely the boundaries of ownership. And if the boundaries based exclusively on this ground—such as walls, fences, and the like—were to fall, then we would stand before a whole, i.e., before a grouping of numerous auxiliary industries around the slaughterhouse.

Whoever knows the Berlin slaughterhouse knows that it is connected with a large number of auxiliary industries; moreover, almost in its very midst, among other establishments, there is even a large private leather factory, so that to the uninitiated it appears to be part of this enormous municipal institution. And it could be such a part without any obstacles of an industrial-police or sanitary character. For what could be more natural than that the many thousands of hides produced at slaughter should be processed right there on the spot and emerge as finished leather goods, yielding major savings in transport and in the organization of the enterprise.

Another example is the Hamburg slaughterhouse, which is directly connected with a tallow-rendering plant, and this plant prepares not only the lower grades of tallow but also margarine. Further, in Vienna, a large slaughterhouse belonging to the city has been planned, at which, among other proposed ancillary industries, the establishment of its own margarine plant and leather factory is also being planned.

Judging by these examples, there is nothing impossible in this—and perhaps somewhere it has already been carried out—that, alongside a tallow-rendering plant at a slaughterhouse, the manufacture of candles and soap should be undertaken.

In many places they have already come to combine, at a common site, the slaughterhouse and the knackery—the latter in the form of an establishment for the thermal processing of animal carcasses. Thus two industries are linked here which, at first glance, and in terms of raw material and final product, have nothing in common; and despite this difference, they are combined for common work, with a view to general economic success. And once this step has been taken, then none of the above-mentioned industries has any reason to be excluded from the number of establishments arising at slaughterhouses.

Thus, at the present time there is no doubt that the enormous development of the work of modern slaughterhouses leads, among other things, to the establishment alongside them of institutions for the processing of animal waste, something that previously seemed entirely inadmissible. And there is nothing surprising in the fact that in the above-mentioned model institutions, facilities for the processing of waste are also combined with slaughterhouses. This innovation, to which one may wish broad success, may be regarded as an achievement of modern technology, the consequence of which is the common good.

The greater the work of slaughterhouses and the number of animals killed, the greater will also be the number of ancillary industries. Therefore cities with large populations, where they still refrain from introducing these enterprises into the plan of slaughterhouse operations, will sooner or later come to establish them.

From a purely technical point of view, ancillary industries at slaughterhouses may be divided into two groups: ancillary industries of slaughterhouses in the narrower and in the broader sense. Among the auxiliary institutions in the narrower sense of the word should be counted facilities that deal specifically with the rendering harmless of waste, i.e. its processing into non-putrefying raw material for various industrial and economic purposes, as, for example, into finished material for agricultural fertilizer (compost, fertilizing fats). Processing in this case is usually reduced to the purification and preservation of waste that is readily subject to spoilage. Among the ancillary facilities in the narrower sense of the word may also be included the removal of waste, the drainage and purification of wastewater, the destruction or thermal processing of confiscated materials, the manufacture of manure powder, the salting and drying of hides and hair, the cleaning, salting, and drying of intestines, the processing of intestinal mucus, the initial processes of blood processing, and the rendering of lard.

To the ancillary industries in the broader meaning of the word belong all institutions which subject the raw materials obtained during slaughter and brought to a certain degree of immutability, or raw materials that are themselves difficult to alter, to further processing for technical or consumer purposes. These should include: tanneries, glue works, brush-making establishments, factories for dressing gut strings, for processing blood, for obtaining stearin and olein, glycerin, fatty acids, margarine; soap works, candle and tallow-melting plants, plants for processing bones, etc.

The boundary between by-product industries in the broader and narrower sense of the word cannot be drawn with strict precision. There are establishments that stand precisely on this boundary, such as, for example, factories for the processing of blood, or those that fall into both categories, such as tallow-rendering works, if the rendered product is sent on for further processing.

In addition to this purely technical subdivision, it would be of interest to establish a classification of these industries with respect to the degree of their sanitary danger and, in general, of the nuisances connected with their establishment for the surrounding population.

Such nuisances, generally speaking, are sharply reduced by the use of the newest technical methods of production. But in the absence of these, or when the industries function improperly, these nuisances may appear to a greater or lesser degree, depending on the type of production. It is therefore desirable to pause over the question of subdividing the industries in this respect and, subsequently, to touch upon the question of how justified are the complaints that arise against all by-product industries of slaughterhouses in general.

It must be said, however, that it is extremely difficult to carry out a strict classification of industries from this point of view. One may, of course, define as safe in the sanitary respect those establishments whose products go exclusively for human consumption. A consequence of such a purpose is the processing of selected, fresh raw material with sufficient care. In the production of the remaining manufactured products, serving technical or agricultural purposes, a strict subdivision in the sense of sanitary danger is almost impossible, since here the condition of the material (time of holding), the scale of production (the mass of materials going into processing), and the methods of arranging and conducting the work very easily cross the limits established on the basis of sanitary principles. On the other hand, gradual improvements in production techniques more and more often transfer into the category of entirely safe those industries that were formerly considered suspect. Hence it happens that the danger from by-product establishments of slaughterhouses is assessed erroneously even by persons who, in general, may be considered experts on these establishments. Thus Ostertag, in his very widely circulated Handbuch der Fleischbeschau, writes: “Among the industrial establishments at slaughterhouses (smokehouses, sausage factories, glue works, albumin factories, facilities for salting hides, tallow-rendering works, margarine factories, establishments for obtaining bone lymph),

which may be encountered in a cattle slaughtering plant, only those may be considered permissible whose production does not give off an odor and does not present inconvenience in any other respect for the slaughterhouse proper. Premises for salting hides, and especially margarine factories, should not be connected with a slaughterhouse, since they are not free from odor. On the contrary, establishments for obtaining fatty lymph are very advisable.”

That margarine factories at the present time operate without admitting odor into the premises is an indisputable truth. It may likewise be asserted that premises for salting hides belong to entirely safe auxiliary installations, fit very well with slaughterhouses, and in many places are directly connected with them without any harm to the slaughterhouses or to the surrounding population.

We have already mentioned that auxiliary installations at slaughterhouses for processing residues, and in particular the refuse of slaughterhouses, confiscated materials, and animal carcasses, have not infrequently aroused—and still arouse—complaints on the part of the inhabitants of the nearest environs. When plans arise for the construction of such establishments, heated protests repeatedly appear on the part of the residents of the given district, and the authorities upon whom permission for the enterprise depends are inclined to take these protests into account and either prevent the construction of these establishments or, at the very least, burden it with special conditions, often very onerous and difficult to fulfill. It must be admitted that there are sufficient grounds for this in the past of similar establishments. In fact, works for the processing of substances of animal origin, with their former types of arrangement, almost always led to complaints from the local population, and in the majority of cases the justice of these complaints had to be acknowledged. The cause of this must be sought as much in the imperfection of the appliances applied to the undertaking as in the careless conduct of the business and inattention to the interests of the surrounding population. This circumstance, of course, was bound to arouse a special distrust of all such establishments, even if their technical equipment had been designed and arranged in the best manner.

However, during the last decades there have been enough occasions to observe examples of an irreproachable organization of the work in a number of auxiliary industries attached to slaughterhouses, including even establishments for the processing of animal refuse. These examples should serve, and do serve, as models in drawing up new projects for establishments of this kind. In any case, at the present time one may say that, on the basis of the available experience, with

conditions of applying modern improved methods of work and of adopting certain precautionary measures, it is possible to arrange all kinds of subsidiary industries at slaughterhouses in such a way that the inhabitants will indeed be protected from the harmful influences about which they formerly had the right to complain.

Thus at the present time municipal administrations have every possibility, when drawing up plans for slaughterhouses, to provide for the broad development, in connection with them, of subsidiary industries for the rational processing of the remains and wastes of slaughter, for the most profitable economic utilization of all valuable parts of these elements, without fear of provoking justified complaints on the part of the population of the districts nearest to the slaughterhouses. And the present moment is especially convenient for the wide application of these innovations, in view of the rapid growth—parallel with the growth of the population—of slaughterhouse operations, which require expansion, reorganization, and development on rational foundations.

Since public slaughterhouses, together with all the institutions belonging to them, serve the interests of the public good, it is desirable that their development should proceed entirely in accordance with this principle; and that, at the same time, they should be regarded as a useful public institution, and that those prejudices which broad strata of the population entertain toward them—partly justified, partly dependent on prejudice—should be destroyed without remainder. These prejudices, and even those often insufficiently justified, will fall away of themselves if the arrangement of subsidiary industries at slaughterhouses and the conduct of affairs in them are in every respect in accord with the rules of hygiene, which in each given case can be sufficiently ensured by the use of modern improved technical devices and methods of production.

IV. General concepts concerning the rendering harmless of slaughterhouse wastes and animal carcasses.

The danger to the health of the population arising from slaughterhouse wastes and from the carcasses of fallen and especially infected animals has always been, to a greater or lesser degree, clear to people. Therefore one or another, more or less perfected, method has always been applied for rendering these elements harmless.

Since I have set myself the aim of describing the modern, most perfected methods of rendering harmless, I cannot fail to mention briefly the metho—

methods of disinfection that are more primitive, in their successive historical or everyday change. I am prompted to do this, apart from the purely historical significance of such information, also by the fact that a considerable part of the less perfected and even primitive processes is still in use, perhaps even very widely, especially among us in Russia.

In antiquity there existed the simplest method of destroying the refuse of slaughter and the carcasses of fallen and infected animals—the method of throwing them away. It consisted merely in the fact that the refuse and carcasses (after the skin had been removed from the latter—the most ancient of methods of utilization) were thrown out at a sufficient distance from dwellings, where they underwent decomposition in the air, destruction by beasts, birds, and insects. There is no need to speak of the inconveniences and sanitary danger of such a simplified method of disinfection.

The imperfections of this method became, little by little, clear to people, and this most primitive way of dealing with refuse was replaced by another method, likewise simple, but undoubtedly far more reliable, and therefore one that has received the widest distribution down to the present time. This is the method of burying carcasses in the ground to a greater or lesser depth, considered sufficient for their safety in sanitary respects.

But this method has a major drawback, consisting in the fact that the source of infection, the infectious microorganisms, are not destroyed, but, as has been proved by irrefutable experiments, remain preserved in the soil for many years. Under favorable conditions these microorganisms can be carried by insects or by means of groundwater and can contribute to a new development of the infection. In this connection experiments are known which have confirmed the viability of the microorganisms of anthrax after their presence in the soil for many years. The danger associated with burying animal carcasses is increased further by the fact that in practice burial is almost always and everywhere carried out carelessly, and in handling animal carcasses there is a tendency to derive some benefit from them, for which purpose people try to put to use at least the hide of the carcass, and sometimes even the fat, as a result of which pathogenic substances are given the opportunity to spread. On the other hand, this method deprives one of the possibility of utilizing a considerable quantity of the useful parts of carcasses. The danger in sanitary respects presented by carelessness in burying carcasses, the impossibility of regulating the proper conduct of this work, and

economic considerations pointed to the need to introduce more advanced methods of disinfection.

Recognition of the shortcomings of the burial method, especially sanitary ones, is a matter of the most recent time. From that moment, methods of disinfection began to be proposed and applied which truly guaranteed the safety of the wastes, although they were far from always advantageous and feasible from the economic point of view.

The first of these, naturally, as the realization of the idea of radically eliminating the sanitary defects inherent in the preceding method, was the method of incineration. This method, proposed and applied as the most perfect from the standpoint of sanitation, does indeed solve the problem of disinfection. To carry it out, various devices were used, beginning with ordinary bonfires and ending with special crematoria. Indeed, the method of incinerating wastes may be called a more reliable and rapid method of destroying their dangerous parts. But this method entails enormous expenditures for fuel, while the only useful product thereby obtained—fertilizing ash—does not at all recoup the large expenses required for its execution.

Modern technology, having early drawn attention to the uneconomical nature of this method, set itself the goal, in addition to the radical disinfection of fallen and infected carcasses, also of utilizing all the valuable substances contained in them and capable of serving as objects of sale. Naturally, this latter method of disinfection is incomparably more advantageous, if apparatuses are available that fully satisfy both aims. And indeed, in recent times such types of apparatuses have been developed that from the wastes, even of diseased animals, processed in them, entirely harmless products are obtained which have consumer value. The most perfect of these apparatuses operate almost without stench, and therefore can be placed even within the limits of a city or settlement. Such methods and apparatuses over the last 2–3 decades have gained considerable spread abroad, and more recently are beginning to be applied with undoubted success and benefit here in Russia as well.

At the beginning of this section I noted that the change in methods of disinfecting slaughterhouse wastes and animal carcasses is a process not so much historical as everyday and practical. And indeed, not one of the above-enumerated methods has completely disappeared up to the present time, not excluding the method of throwing away, practiced by far not only among savage peoples.

But among the methods of rendering wastes harmless that are used at the present time with the permission of the law, there are three:

1) removal from the place of slaughter;
2) destruction on site;
3) processing on site in order to obtain by-products.

The essence of each of these methods has been sufficiently clarified in the preceding exposition, while the details of execution will be the subject of special sections. Here we shall confine ourselves only to a few general remarks of an economic nature.

With respect to the economic side of the matter, it must be said that all three methods of rendering slaughterhouse wastes harmless, in order to be carried out consistently, require much attention, trouble, and expense. As regards the methods of removal and destruction, this will need no explanation if one takes into account the quantity of wastes at any slaughterhouse. And practice indeed shows what a heavy economic and administrative burden wastes create for every slaughterhouse. Methods for utilizing wastes make it possible to lessen this burden, while attaining sanitary objectives in the best possible way and at the same time making use of the valuable parts of the wastes. But after the introduction of establishments intended for the purposes of waste utilization, there is sometimes a tendency to impose excessively high demands upon them. One observes, both in their construction and in the discussion of projects for such establishments, a tendency to regard each of them as an industrial enterprise obliged fully to recoup its expenses. Such a view is incorrect and, when put into practice, leads to rejection of the planned facilities and to harmful economizing on the expenses of existing establishments. Facilities for rendering slaughterhouse wastes harmless must be regarded as institutions pursuing, above all, sanitary aims. They must recoup their expenses to such an extent that their maintenance costs no more than other methods of rendering harmless. And even this latter condition is not obligatory, in view of the serious collateral benefits, in sanitary respects, afforded by their introduction, which are often worth a considerable surcharge. In any case, they easily satisfy this condition in the majority of cases. A considerable number of them are substantially more profitable; there are also many that recoup all their expenses and even bring in a significant income. Such, for example, are plants for the utilization of confiscated materials and animal carcasses. But to demand the same of facilities for the utilization of less valuable products is, of course, impossible. They must always be evaluated in comparison with the cost of those pri—

... primitive methods which they replace, without stopping at the expense, in view of achieving more perfect or sanitary aims.

From the sanitary point of view, the following general provisions must be noted.

When removing refuse, it should be made a rule that it be removed on the very day of slaughter, and moreover to uninhabited places, or else to establishments intended for its destruction or processing and equipped accordingly. A good system of drains for liquid refuse (wash waters, etc.) and a carefully organized and reliably regulated cartage are matters of primary importance for slaughterhouses. In the destruction and processing of refuse on site, i.e. at the slaughterhouse itself, the absence of odor during the work can be spoken of only with respect to the more immediate surroundings. But with both methods there are odors which must be limited even in the nearest neighborhood, which, under certain conditions, is feasible. This applies chiefly to heavy odors arising from the decomposition of refuse or carcasses. The chief requirement in the present case, already in the interests of the working personnel, consists in ensuring that the destruction and processing of refuse be carried out in as fresh a state as possible. Therefore neither storage nor piling up for the purpose of later processing should be permitted; no arrangements of this kind should be allowed, such as storage chambers, pits, etc., by means of which prolonged keeping of refuse, with all its consequences, could be practiced. On the same grounds it must be considered inconvenient and inadmissible that residues or refuse obtained elsewhere should arrive at any slaughterhouse or its auxiliary works, or that raw material should be brought in which, owing to lying elsewhere or owing to the duration of transport, may have begun to decompose.

Not wishing in the present article to enter into the details of methods for removing refuse, since its main subject is destruction and utilization, I shall confine myself to including in the present section a small amount of information on this question.

The items subject to removal from slaughterhouses are chiefly blood, the contents of the stomach and intestines, skins, hides, hair, fat, parts not intended for consumption, such as, for example, confiscated materials. Further, this also includes the removal of wastewater, as well as the carting away of sludge from installations for clarifying and purifying wastewater. We shall speak only of the removal of solid refuse.

The removal of these substances as quickly as possible and to as great a distance as possible from slaughterhouses and inhabited places is, without doubt, the best means of preventing the nuisances that may arise from them. With conscientious application of this measure, slaughterhouses can be maintained in a condition that meets the requirements of hygiene and does not offend the smell or sight of residents. This method of removal is very often used and, among other things, has withstood a serious test in its application to the Hamburg slaughterhouses, without any inconvenience either to the slaughterhouses themselves or to the surrounding district. There the blood, stomach and intestinal contents, intestinal mucus, hair, and confiscated materials are taken away daily in specially constructed and tightly closed carts and are partly deposited far beyond the city limits, partly processed in special establishments. Of course, one may object here that the inconveniences associated with refuse are merely transferred from one place to another and do not cease to be harmful to people living near the dumping sites. In view of this inconvenience, the question arises whether the removal of refuse is a sufficiently reliable method in relation to all refuse, and whether it would not be better to destroy the more suspicious refuse on site by more radical means, under proper supervision. The latter opinion is becoming increasingly widespread and seems the most correct.

Several figures, which we shall now give, will show us what an enormous quantity of slaughterhouse refuse is subject to removal. Thus, for example, in Hamburg the quantity of manure removed in 1903 amounted to 5.87 million kilograms. Of this, 3.66 million kilograms came from the slaughterhouse. Of these, 4.38 million kilograms were sent by rail, 1.11 million kilograms were taken by purchasers and sent on their own horses, approximately 80,000 kilograms were sent by water, and the remaining quantity was removed by means of transport belonging to the slaughterhouses. In Berlin, in the same year, the amount of manure carted away from the slaughterhouses and cattle yards was 15.41 million kilograms. Of this quantity, 6.16 million kilograms came from the slaughterhouse.

It is clear that the transport of such a mass can be carried out only when the masses of manure can be taken not too far from the slaughtering site. As the distance increases, transport costs also rise. Consequently, for this method of disposal there is a limit beyond which other methods must be sought for rendering the refuse harmless.

In addition to careful regulation of the order of removal, the selection of suitable and sufficient means for this purpose is, of course, of some importance. If specially designed carts are used, they must close in such a way as to let through neither water nor air, and their loading and unloading must take place in as simple and rapid a manner as possible. It is especially important that the refuse be loaded into the carts or barrels for removal immediately at the very place where it is collected, and that there always be a sufficient supply of transport equipment. To allow refuse to remain for a prolonged period in slaughterhouses by means of cement-lined pits that do not let water through, and that are emptied as needed, is rather dangerous, since one may readily expect a rapid transition of part of the contents of the pits into putrefaction, with all the consequences of such a process. The movement of refuse, especially of dense refuse—such as intestinal mucus—within the slaughterhouses themselves, across yards, in open or poorly closing vessels, must likewise be avoided, as must transferring it from one vessel to another. Each vessel must be well closed at the place of loading and dispatched at once. Only in this way can the contamination of yards, passageways, etc., be avoided.

Manure intended for further agricultural use must not lie in heaps under the open sky. As is known, this lowers its agronomic value under the influence of sun, rain, and wind; on the other hand, the inconveniences of its proximity to the nearest settlements are increased. Prudent rural proprietors therefore equip manure-storage sites with roofs. It may also be covered with earth, and where this is applicable, with peat.

V. Destruction of slaughterhouse refuse and animal carcasses.

By the destruction of slaughterhouse refuse, in the narrow sense of the word, is meant its complete rendering harmless without obtaining any products whatever for use, whether for technical or agricultural purposes.

Naturally, only that refuse is subjected to destruction whose technical use, owing to low value or danger from the sanitary point of view, is unprofitable or dangerous. Thus refuse contaminated with infectious pathogenic substances is, without doubt, subjected to destruction as the most radical method of rendering it harmless. Destruction of readily decomposing refuse may likewise be proposed wherever the removal system, for whatever reasons,

was guided by considerations inapplicable to low-value wastes. It is especially convenient to employ the destruction of wastes if their inflow is not so great as to justify the introduction of proper processing, and if the costs of destruction do not exceed the costs of processing. This case is always, or often, encountered in application to small and medium slaughterhouse establishments, and also to a number of knackeries, which receive quantities of raw material insufficient for the organization of profitable processing.

The simplest method of destroying wastes has, from ancient times, been burying them in the ground. This is the most primitive, and at the same time the most questionable, method. It provides the necessary safety from the sanitary point of view only if it is applied with observance of the proper rules and precautions. In this case the destruction must be carried out by burying in places that are not visited by animals. Before burying animal carcasses it is useful to cover the carcass with deep incisions and sprinkle it with lime, or pour coal-tar pitch or carbolic acid over it. The pits must be dug to such a depth that the upper surface of the carcass is covered by at least one to one and a half arshins of earth.

This method of destruction, as is known, is very widespread, but it can and should be used only in the event that recourse cannot be had to more advanced methods. It gives no serious guarantee that wastes or carcasses subjected to this process will no longer have any undesirable effect.

Consequently, this slow process of decomposition or oxidation in the earth must be replaced, wherever possible, by vigorous and rapid destruction by means of fire. In particular, one may insist with full justification that animals which have died of suspected infectious diseases should not be buried, but burned, where there are no other, more advanced installations for destruction. Such burning can be carried out in the simplest manner in temporary pits dug in the ground. The German specialists Lothes and Profé point out that in such temporary furnaces, if they are properly constructed, the burning of carcasses of large animals proceeds satisfactorily. In this case the burning of a carcass weighing 6–8 centners requires about 5 hours and the consumption of 3–4.5 centners of firewood; for burning a carcass weighing up to 15 centners, 10–12 hours are required, and 6.5–7 centners of firewood.

This method of incineration is used when there are no permanent installations for the destruction of waste. It is suitable for remote backwaters, but by no means for slaughterhouses and the institutions connected with them. If it is necessary here to destroy by fire slaughterhouse confiscations, animal carcasses, etc., then special installations are needed, constructed in the best possible manner and impeccable from a technical point of view.

Initially an attempt was made to use the furnaces of steam boilers for burning animal waste. But these experiments gave very poor results, so that this method of destroying waste, which at first glance seemed expedient and convenient from an economic point of view, was soon completely abandoned. The formation of soot, suffocating and extremely unpleasant gases, the appearance of rust and considerable damage to the walls of the boiler, owing to the release of water vapor, were the cause of this. The latter circumstance was especially harmful, since it required frequent and costly repair of the boilers. In view of the failure of this method of incineration, it became necessary to resort to special furnaces for burning animal waste and carcasses, which were quickly improved to such an extent that at the present time they are quite expedient. Such furnaces (so-called destructors) are used up to the present almost exclusively for the destruction of slaughterhouse confiscations at slaughterhouses, especially where processing installations seemed too expensive or other difficulties were encountered. Particularly well known in application to slaughterhouse waste are the furnaces of the Kori system, which quickly came into use and were adopted in a whole series of slaughterhouses in Germany.

The construction of these furnaces is shown in drawing 1 (plate I). The waste enters through door E into the combustion chamber V in the form of an inclined channel, beneath which is the vault G₂ with through openings and with the horizontal continuation G₃. The flame, formed in the main firebox F, for the most part passes by the waste lying in the combustion chamber V and rushes into the vertical flues Z₁ and Z₂. A smaller part of the flame passes into the lower passage K and dries the waste from below, for which purpose the openings in vault G₂ serve, also helping to equalize the temperature in both chambers. The dried and half-burned waste is lowered into the firebox F and there burns up completely. In order to prevent the escape of suffocating gases, a second firebox is provided, the flame of which meets the gases going—

… by chimneys \(Z_1\) and \(Z_2\), before the latter enter the exhaust flue \(O\), connected with the pipe, and promote their combustion.

These special furnaces are made in 8 different sizes for charges from 250 to 900 kilograms. The length of the furnaces ranges from 2.46 to 3.63 meters, the width from 1.16 to 1.68 m, and the height from 2.20 to 3.10 m. They are built of brickwork, with an interior lining of refractory brick and with the walls strengthened by tie-rods.

As regards the productivity of these furnaces and the expenses for them, the following data may be given, reported by Mr. Theobald concerning the Cory-system furnace in the town of Nijmegen. The consumption of fuel (coal), even with an especially unfavorable composition of the material (an abundance of water or a low fat content), does not exceed 150 kilograms for a charge of 600 kilograms during 10–11 hours of operation. The burning of one kilogram of meat costs about 0.4 pfennig. This expense is considerably reduced if the incoming material is rich in fat, and if the furnace operates through several charges in succession without cooling. The furnace in Nijmegen destroys all slaughterhouse confiscations, refuse, and also the carcasses of fallen animals of the entire city, with a population of 47 thousand persons, and of two adjacent villages. Under normal conditions, one charge per week is sufficient to destroy all the accumulated material, and only in exceptional cases, when large carcasses arrive, is it necessary to make two charges per week. In the town of Mysłowice, for the burning of 1200 kilograms of slaughterhouse refuse, from 100 to 200 kilograms of coal are required, depending on the fat content in the refuse, i.e. on average 150 kilograms. This is such a small expenditure that it almost disappears in comparison with the consumption of coal for the steam boilers. Since the furnace for burning refuse is served here (in Mysłowice) by the same stoker who is stationed at the boilers of the machine building of the slaughterhouse, the small quantity of coal, amounting to several centners per week, constitutes almost the only expense required by such a furnace in the present case.

For constant work in burning animal carcasses it is more convenient to use double furnaces. When fresh and moist material is fed into a hot furnace, the refractory lining of the walls may become disordered, so that frequent repairs may be required. By installing a second furnace, this inconvenience can be eliminated and work can be carried on by alternating daily, now in one, now in the other furnace; moreover, during the intervals the interior of the furnace can cool down sufficiently that a new charge may be introduced without harm. In Nuremberg such a double furnace has been in operation since 1895. It is housed in a special annex near the boiler room and is connected with the smoke pipe of the boilers.

For the destruction of livestock-slaughter refuse in England, destructors of various systems are used, of which the best known are the destructors of the Fryer system and of the Horsfall system.

The Fryer destructor is the oldest in date of appearance, but is still widely used, although it has one drawback, which will be discussed below. In schematic drawing 2 (Plate II) a double destructor of the Fryer system is shown. It consists of two furnaces, joined together, A, A, lined inside with arches of firebrick. The dimensions of the furnaces are: length 9 feet, width 5, and height up to 3½ feet. The fire-grates B, B are arranged on an inclined plane with a slope of 1:3. The refuse enters from above into a special hopper C, C and at first falls onto a solid hearth D, D of firebrick, approximately 4 ft. long; then from time to time it is pushed forward and passes onto the fire-grates, where it is finally burned. The products of combustion enter the common collecting horizontal flue E and are carried off into the chimney. Each separate furnace of this system can burn about 500 poods of refuse per day.

This destructor has one drawback, which consists in the fact that the gases produced during the drying of the refuse on the inclined blind hearth fly off into the chimney without passing through a high temperature. It is obvious that the purpose of a destructor operating within a city should be that all products of combustion pass through a high temperature, which would ensure their complete decomposition into harmless components. In the present destructor this purpose is not achieved, since the openings for filling the furnace with refuse and for the exit of the products of combustion, as can be seen from the section, are so arranged that they form two completely adjacent parts of the destructor. This circumstance also makes it possible for gases not subjected to the action of a high temperature to escape. To avoid this undesirable phenomenon, a special device called a “cremator” of the Johnson system began to be applied to such furnaces (analogous to that found in the Kori destructor), where the gases pass through a second firebox and are burned before entering the chimney. Unfortunately, the installation of cremators increases the cost of operating the destructor, and in some places they have been abandoned for reasons of economy. Investigations in Bradford showed that burning with the use of cremators costs 50% more.

In schematic drawing 3 (Plate II) the destructor of the Horsfall system is shown. It differs from the Fryer destructor in several important details. Here, above the arch of furnace B, there is placed

a large chamber C, into which, through the openings in its arch b, b, b, the products of combustion enter for more complete decomposition. The outlet for the gases, F F, as is seen from the drawing, is arranged quite separately from opening E, through which the refuse enters for incineration. In this way all the gases must pass through the hottest place, where they too are subjected to decomposition. A special feature of Horsfall’s destructor is also that, in order to intensify combustion, an artificial steam draught is usually employed in it by means of steam-jet apparatus, or air is supplied with the aid of fans.

Let us incidentally point out some details of the construction of destructors. The charging doors for destructors are usually distinguished by considerable weight, and therefore are opened and closed with the help of counterweights and weights. The furnace doors differ hardly at all from ordinary ones. Drawings 4 and 5 (Plate III) show types of charging doors.

The fire-bars of destructors are made fixed or movable. Drawings 6 and 7 (Plate III) show types of fixed fire-bars. Drawing 8 depicts movable fire-bars with moving rods, and drawing 9 the supports along which their movement takes place. The movement itself may be produced either by hand or automatically from moving mechanisms. The complexity and certain inconveniences of movable fire-bars, especially with mechanical motion, cause preference in practice to be given to manual movement, and do not allow movable fire-bars in general to become widely adopted.

The chimney is a very important part of the apparatus. On the proper arrangement of the draught and the after-burning of the gases depends the entire reputation of the destructor and its sanitary significance. The height of the chimney, of course, is of great importance for the success of the draught, and in these forms it has often been necessary to raise the chimneys of existing destructors. The height of the chimney also has an influence on the breadth of dispersion and dilution of the gases issuing from it.

In the following table are given the dimensions of the chimneys of destructors in several English towns. These destructors are used for the destruction of all municipal refuse in general, and therefore all of them consist of several furnaces.

Name of city.	Number and system of furnaces.	Cross-section of furnace.	Height of stack.	Internal diameter, bottom.	Internal diameter, top.
		m	m	m	m
Southampton	6 Fryer.	0.60	49	2.14	1.83
Bath	12 Fryer.	0.39	56	2.45	1.53
Leicester	6 Fryer.	0.525	49	2.00	1.53
Same	6 Fryer.	0.69	58	2.14	2.00
Leeds.	8 Fryer (with injector).	0.44	79	2.00	1.82
Oldham.	10 Horsfall.	0.26	15.3	1.82	1.82

From this table we see that the height of the stacks of the Horsfall destructors is considerably less than that of the stacks with Fryer destructors. This is explained by the use of a system of steam injectors (or fans), which increase the draught. The Horsfall company regards—and, of course, to a certain extent justifiably—this circumstance as an advantage of its system. But at the same time one should not lose sight of the fact that, first, the injectors require an expenditure of steam and repairs, with cessation of operation during the latter; and, secondly, from the sanitary point of view a greater stack height guarantees greater dilution of the issuing gases.

The injector of the Horsfall system, used for increasing the draught in destructors, is shown in drawing 10 (Plate IV). It consists of two cones joined by their narrow ends and attached from inside to the ash-pit door. A steam pipe, passing through the door into the front cone, conducts steam, by whose motion air is carried through the free opening of the cone, and thereby the draught in the destructor is considerably increased. By using these injectors, the Horsfall company has considerably improved its destructors. When they are used in the furnace, such a high temperature is obtained that everything is heated white-hot, and the gases, passing first through the top of the furnace and then through the combustion chamber, are radically burned up and rendered harmless. According to the experiments of engineer Ransom, it has been established that the steam injector in a Horsfall destructor consumes up to 113 kilograms of steam per hour.

Drawing 11 (Plate IV) depicts the Kerting injector, used for the same purpose. Its construction is clear from the drawing. It consumes 35–40% less steam than the injector

Gorsfolla, and moreover it acts silently, which cannot be said of the latter.

The action of injectors is expressed in the fact that the ratio of the quantity of air passing through to the quantity of material burned is reduced, and the temperature of combustion in the firebox is raised. According to the experiments of Ferlet, in a furnace without an injector the volume of all the air passing through was 32 times greater than the volume of the refuse being burned, while the application of an injector to the same furnace reduced this ratio to 1:7.64. On the other hand, on the basis of the experiments of Dr. Cameron in Leeds, the temperature in the firebox when injectors are used rises by almost 250° C.

In applying destructors at slaughterhouses it must again be recalled that, for the sake of convenience in installation and operation, they are not infrequently connected with the boiler rooms of machine buildings, and in that case they are not, of course, provided with special chimneys, but are connected to the flues of steam boilers.

With this we shall conclude our consideration of the question concerning the rendering harmless of slaughterhouse refuse and animal carcasses by means of incineration. In the interests of the sanitary protection of slaughterhouses, it is desirable that a furnace for burning animal refuse be available at every slaughterhouse, as a means for the radical disinfection of suspicious materials of animal origin, for the safety of the working personnel and of the population in general. It is equally necessary in the event that, during repairs to the apparatus for processing, confiscated materials and carcasses should not lie for days and weeks and enter processing in a state of decomposition. They may also be used for the destruction of other refuse which, by reason of its quality or quantity, cannot be removed or utilized. When such furnaces are connected to existing boiler plants, their installation involves very small expenditures and in any case is repaid by the benefits that they provide.

VI. General concepts concerning the rendering harmless of slaughterhouse refuse and animal carcasses by means of utilization.

The processing of slaughterhouse refuse occupies the broadest and most important place in the field of rendering refuse harmless. Here one has to do with obtaining a number of useful products, very valuable in technology and agriculture.

Of the refuse from slaughterhouses, the most important are, first, blood; second, the contents of the stomach and intestines; and third, finally, confiscated materials. With regard to the latter, in terms of technical

methods and products of processing, as was indicated above, also adjoin animal carcasses. The closeness between these elements from a technical point of view, under modern methods of treatment, is so great that there is every reason, when setting forth the technical aspect of the matter, to consider them jointly, merely noting in passing certain special features relating chiefly to the hygienic qualities of the raw material.

The processing of the above-mentioned types of refuse is reduced to the following. From blood, albumin is obtained, used chiefly in dyeing technology, while the residues obtained in the processing for albumin are converted into nutritive or fertilizing greases. The contents of the stomach and intestines, as well as intestinal mucus, are converted into agricultural fertilizer, the latter also into feed grease. Confiscated materials and animal carcasses, when processed, yield fat (which constitutes material for further processing), feed greases, and fertilizing greases.

The technical installations intended for processing slaughterhouse refuse of one kind or another constitute special ancillary industries, under the name of utilization plants, which are organized either at the slaughterhouses themselves or as separate independent institutions. The details of the technical arrangement and equipment of individual institutions of this kind will be set forth separately in the following chapters. Here we shall say only a few words about the hygienic features that apply equally to all these institutions, as well as about the administrative organization of such institutions.

The processing of slaughterhouse refuse, from the point of view of the inconveniences caused both to the surrounding population and to the working personnel of the institutions of this kind themselves, is, with few exceptions, an unpleasant process requiring great care and precautions. Even at the present time, existing institutions far from always satisfy the requirements imposed upon them in the interests of the population and the working personnel, although, on the other hand, isolated cases may be pointed out which undoubtedly show that institutions of this kind can be conducted quite irreproachably even in the midst of populated places.

The dangers that arise from installations for processing slaughterhouse refuse are very characteristic of the entire group of ancillary slaughterhouse industries. The dangers to the surrounding population are chiefly the following:

1) the emission, from liquid residues and refuse, of easily decomposing and sometimes infectious-substance-contaminated matter;

2) the emission of offensive and nauseating odors;

3) the breeding of insects, mice, and rats, and the resulting inconvenience and danger of infection.

For the working personnel of the establishments themselves, the dangers consist of the following:

1) prolonged inhalation of unpleasant odors and vapors, and sometimes also of a considerable quantity of dust;

2) prolonged stay in wet or damp premises;

3) the frequently threatening danger of infection by pathogenic organisms (for example, anthrax);

4) handling unsafe materials, devices, and machines.

Therefore, in locating, arranging, and equipping establishments for the processing of slaughterhouse refuse, it is necessary carefully to assess the above-listed hazards in advance and to adopt those measures which appear appropriate and sufficient, as far as possible, to neutralize them. In accordance with the nature of the inconveniences that must be feared in the establishment of institutions of this kind, the requirements that should be imposed upon them may, in general outline, be reduced to the following provisions:

1) Refuse should enter processing, as far as possible, without delay;

2) Manipulations with raw materials should, as far as possible, be limited, and with infectious materials entirely excluded;

3) In the raw state there may be left only those products which, by themselves, resist decomposition;

4) Further processing of the materials, up to the obtaining of rendered harmless and finished products, should take place in an enclosed space, without communication with the external environment;

5) The quantity of liquid, readily decomposing substances obtained as a result of the processing operation should be reduced to the possible minimum;

6) Processing should pursue the aim that the refuse be wholly transformed into final—that is, rendered harmless, stable, and fully ready-for-sale—products;

7) All parts of the machinery equipment must be properly arranged, placed, and guarded.

Above we spoke of the desirability, from the economic and, if possible, from the sanitary and technical point of view, of arranging establishments for the processing of refuse at the slaughterhouses themselves. Such an arrange-

...the construction of such a facility leads to the necessity of bringing these industries, together with the slaughterhouses, into the sphere of enterprises of a public character under the direct supervision of the cities. It must be said that this is also the best measure from the point of view of the aims pursued by the institutions under consideration. Indeed, the protection of the city’s sanitary interests is ensured only when the management of production is fully conscious of its responsibility toward the population and does not forget the interests of neighboring residents and of the working personnel for reasons of economy. From this it is clear what advantages such an arrangement presents for all, when all the subsidiary industries of the slaughterhouse trade are not in private hands but under the administration of the city.

In this connection, the statements of the Hamburg Senate concerning the city’s rendering establishments are very valuable. They read as follows: “The experience of 1882–1893 has shown us that the preservation of rendering production in the hands of the city, especially from the standpoint of the thoroughness of supervision, should be preferred to a lease system of maintenance. The new views on this subject rightly emphasize that the chief attention in this production must be directed to the destruction of wastes and to hygienic improvements in the organization of production. These requirements, of course, are contradicted by lease-based maintenance, since it is directed only toward profit. Only the direct supervision of a public administration guarantees the careful observance of sanitary measures and can keep pace with all the advances of technology in this field.” Schwartz, an expert on the organization of slaughterhouses, likewise says: “It is unnecessary to prove that enterprises established for purposes of public improvement bring real benefit only when they are under the supervision of an administration that acts completely objectively, and not one that is interested only in profit.”

Thus, every public administration that intends to organize an institution for the rendering and utilization of wastes must make the management of such institutions under the direct supervision of the city a fundamental condition.

It is also necessary to draw attention to the extreme importance, in this matter, of carefully choosing the head of production and the entire staff of the institution. The manager of a utilization plant must not only know the technical side of conducting production, but must also be seriously acquainted with the measures aimed at protecting the hygienic interests of the surrounding population and workers. Therefore, when establishing new institutions he must, as far as possible,

take part in the matter both in designing and in constructing and equipping them, so as to become sufficiently acquainted with the precautions and to learn to value them. The staff of workers must be selected with the greatest care. It is necessary to attract experienced and reliable laborers and to retain them by paying well for their highly useful and difficult work. At the same time it is necessary to instill in the working personnel, and to maintain, an awareness of the importance of the task entrusted to them, a feeling of responsibility before society, and the habit of order and thorough cleanliness.

VII. The arrangement and general equipment of the buildings and premises of a utilization plant.

The proper choice of site and the expedient placement and arrangement of institutions for the processing of slaughterhouse refuse, from the standpoint of the properties of the production being established, can and must guarantee the real safety of the surrounding population; and the expedient internal equipment, connected with the proper conduct of production, is the basis for ensuring the safety of the working personnel. But both requirements for the most part agree with one another to such an extent that they serve jointly toward both aims.

For rendering plants, in the old sense of the word, not equipped with modern appliances, there is reason to apply the requirement that they be situated in complete separation from premises for human habitation and at a proper distance from streets and major roads. As regards utilization plants with modern equipment, however, which operate in entirely closed systems with the observance of all necessary precautions, on a par with other auxiliary establishments of slaughterhouses, there are not sufficient grounds for applying this requirement. In general it may be considered that the authorization and arrangement of such institutions should be made dependent not so much on the site as on the completeness and expediency of their structural and internal equipment. In this respect modern technology provides a whole series of means which, when properly applied, give fully sufficient protection to the hygienic interests of the surrounding population.

Of the site on which buildings for the processing of animal refuse are to be erected, it must be required that it possess dimensions corresponding to the character and size of the production, and that its position be convenient for the arrangement of faultless sewerage. For this purpose it must be connected either with a sewer collector, or with an open stream that would receive the wastewater after appropriate purification.

Another indispensable requirement is that the surface of the yards between the workrooms be covered with an impermeable pavement, i.e., asphalted or arranged in a similar manner, so that contaminated materials cannot stagnate and be absorbed into the soil, and all parts of the yards can at any given moment be subjected to thorough washing. For this purpose, water taps are also necessary, both inside the buildings and in the yards, equipped with flushing hoses.

Buildings intended for establishments for the processing of slaughterhouse refuse must be constructed as solidly as possible and, at the same time, have as elegant an appearance as possible from the architectural point of view. More attention must be paid to this latter circumstance than is usually devoted to it at present, in order to contribute, to some extent, to the destruction of prejudices against establishments of this kind. An elegant and appropriate exterior involuntarily causes a favorable conclusion to be extended also to the internal arrangement of the establishment. The interior setting and equipment of an establishment for the processing of refuse must likewise be not only practical, but also arranged in the best possible manner, in particular so as not to make a bad impression on the eye. The solidity, convenience, and cleanliness of the internal equipment undoubtedly make an extremely important impression on the working personnel in the sense of maintaining the utmost neatness required here. This latter is the basic foundation for such establishments if they truly wish to rid themselves of the suspicion of being dangerous to the population and to the workers.

Turning now to the internal arrangement of the premises for the processing of slaughterhouse refuse, we must say, of course, first of all, that the tendency of the material being processed toward rapid decomposition, with its extremely unpleasant consequences, generally requires extremely careful arrangement of the workrooms, storage rooms, and so forth. Both the dimensions of the rooms and their mutual arrangement, as well as the details of the construction of all their parts—the walls, floors, ceilings, lighting, ventilation, equipment with working apparatus and auxiliary devices—must be developed in the most careful manner, in consideration of the properties, dimensions, and particular features of the individual productions and local conditions. The size of the rooms must be determined for each individual case, and in this respect it is impossible to establish general rules. The more space that can be provided for each operation, the better. In any case, a limit may be established for the height of the rooms. In medium-sized and large ...

in establishments at least 5 meters. If it is more, so much the better for the working personnel.

Since the dimensions of devices for removing odors and vapors are determined by the quantity of substances capable of decomposition that fall upon the floor, walls, and ceiling, the ventilation of premises is substantially facilitated by the constant and thorough cleansing of the interior of the building from these substances. Such maintenance in cleanliness is possible only when the floors and walls are so arranged that they can at any time easily be subjected to thorough cleaning, i.e., washing and disinfection.

The floors of establishments for the processing of refuse must above all be watertight, so that the liquid residues of production can neither penetrate through them into the underlying or adjacent soil, nor be absorbed into the floors themselves. Further, they must have sufficient slopes toward one or several drainage openings connected with the sewerage system, so that waste waters can run off immediately and of themselves. In order to avoid the stagnation of dirty waters in depressions, holes, and cracks in the floor, the most serious attention must be devoted to its construction. Cement and asphalt are best suited for floor covering, especially because they can easily be given any desired slopes. Tiles of granite, sandstone, cement, and terracotta may also be used here, if they are laid tightly on cement mortar over a sandy base and all joints are carefully filled with cement or asphalt. In any case, the use of wood for the construction of floors must be avoided, as also that of small tiles: the former because of its capacity to absorb liquids, and the latter because tiles, as experience shows, are easily displaced, and the spaces between them are difficult to keep clean. For the same reason, one should in general be cautious in the use of tiles, because here putrefying substances easily remain in the spaces and may be the cause of an unpleasant odor.

No less care must also be devoted to the construction of the walls of the premises. Here, too, all measures should be taken so that putrefying substances cannot penetrate into the walls or adhere to them. The walls must therefore, at the very least, be plastered with cement and painted over their entire height with oil paint. In this way cracks are eliminated and thorough washing of the walls becomes possible. It is, of course, necessary to see to it that painting with oil paints is carried out on completely dry walls, and that production in premises arranged in this manner begins no earlier than when the paint has completely dried. With this

circumstance, unfortunately, is often not taken into account. It is often preferred to start production before painting, immediately after plastering has been completed, and to paint the walls with oil paints later, after the plaster has dried. But in doing so it is forgotten that the walls, owing to a certain dampness during production, generally cannot be sufficiently dry, and therefore oil painting carried out under such conditions adheres poorly.

Since oil painting proves not entirely satisfactory in other respects as well, a substitute for it was found in enamel paints and glazes. Such a coating is stronger and considerably smoother, and is therefore washed excellently. Far more expedient and beautiful, without doubt, is the facing of walls with light-colored tiles made of some smooth material, for example with glazed tiles or porcelain tiles. Such facing of walls is, of course, very expensive, but in view of its expediency and durability, in comparison, for example, with painting with oil paints, it is nevertheless gaining acceptance. It is sufficient to install this facing to a height of 2 meters from the floor of the room, while the rest of the wall may be painted with oil or enamel paint. The tiles used for facing walls must be without rabbets, so that there are no recesses in which particles of dirt could be retained. Selected brick, coated with a durable enamel paint, may also be used for facing walls, as may artificial or real marble.

It should further be mentioned that the construction of ceilings in the rooms of a rendering plant must be just as expedient and solid. Here, of course, painting with light-colored oil paints is also required, so that the necessary washings with water can be carried out.

There is every reason to arrange the interior finishing of the workrooms of a rendering plant not only solidly and expediently, but also in such a way that it is pleasing to the eye. That this is possible with the general improvement of production is shown to us by the municipal rendering plant in Dresden. At the sight of the excellent interior finish of this establishment, the walls with tile facing, and the gleaming machines, every prejudice disappears entirely in the viewer, if indeed he had any, regarding establishments of this kind. This example shows that a rendering plant, arranged and equipped as an establishment for thermal processing, entirely in accordance with the principles of modern technology, can have exactly the same appearance as any other mechanical establishment built according to the same principles.

For lighting the premises of a rendering plant one should, whenever possible, make use of overhead light. If, owing to local conditions, lighting by overhead light proves inapplicable, then, naturally, one has to resort to side lighting through windows. But these windows must be kept shut during work, so that some portion of the vapors cannot spread into the surrounding locality.

The isolation of these premises from yards, roads, and neighboring buildings is effected by means of well-arranged ventilation. In order actually to achieve the necessary separation of these establishments from neighboring homesteads, it is necessary completely to eliminate the penetration of air, during work, through doors and windows. The admission of fresh air must take place through special openings. Its outlet, however, must be arranged through exhaust pipes built into the walls, sufficiently high and with the appropriate draft. These exhaust pipes are provided with devices whose purpose is to intensify ventilation. Among the latter may be mentioned, in addition to the ordinary T-shaped cowls, the ventilation cowls of L. A. John (Erfurt), the deflectors of H. Kori (Berlin), Aeolus ventilators of Dr. Plattner (Witzenhausen), Jalousie ventilators of the firm Hürtgen, Monnig & C° (Cologne-Lindenthal), etc.

These ventilation devices, which, as opposed to mechanical ones, are called natural, can be dispensed with only in the rarest cases, in very small establishments that process a small quantity of material. In the majority of cases, in medium-sized and large works, natural ventilation is supplemented or replaced by mechanical ventilation. In this connection one of the most important measures is that in large plants, should they be close to human habitation and to places of traffic, there should at the same time be two independently operating systems of ventilation devices.

Of all devices for operations (apparatus, etc.), it is above all necessary to require that, during production, they work without emitting any odor, i.e., that they not let pass foul-smelling or putrefying liquids, dust, or ill-smelling gases and vapors in quantities appreciable to the surrounding locality. In this respect measures of two kinds must be adopted. First of all, all devices for operations must be sufficiently impermeable, so that there can be no outflow of foul-smelling and decomposing liquids. In addition, they must be placed in such a way that the emptying of ill-smelling liquids can take place directly into the sewerage system, without any odor. Secondly,

Destruction and Utilization of Industrial Wastes.

It is necessary to require that the vapors, gases, and dust developing in apparatuses for the processing of wastes should not be able to find any extraneous outlet, but should remain at the place of their origin until they are properly removed and rendered completely harmless.

These aims are achieved in the best manner when the work is carried out in completely closed apparatuses connected directly with ventilation devices. The latter consist of the necessary number of pipes or ducts connected with one another, an exhauster (fan), and devices for condensing and burning gases and vapors, as well as devices for collecting dust. The condensation of gases and vapors, except in cases where reagents formerly used in production, such as benzine or sulfuric acid, are recovered from the condensates, requires the direct connection of the condensing devices to the sewerage system. Acid compounds must, before discharge into the sewer, be neutralized in tightly closed vessels connected with ventilation. Gaseous compounds that have not been destroyed must, depending on the strength of their odor, either be discharged into the air by means of a high pipe, or before this be introduced into some furnace, so that they may be burned there. With a small quantity of readily combustible gases one may use the furnace for boilers. But it is better and safer to carry out the detoxification of a large quantity of gases by introducing them into a furnace specially constructed for this purpose, in which the gases must pass through a layer of incandescent coke approximately 0.50–0.75 meters high. In doing this, measures must be taken to ensure that, during combustion, the gases do not form an explosive mixture and do not produce an explosion in the ducts (incandescence of wire meshes, etc.).

The absence of devices for burning gases that are not subject to condensation has a very unpleasant effect on the neighboring population, and such devices must be required in every case. One must always strive to have the work proceed in completely closed, impermeable apparatuses, with the immediate removal, condensation, and destruction of gaseous products and the direct discharge of liquid residues. It is very advantageous, when water under pressure is available, to absorb and remove unpleasant gases and vapors by injecting water, since in this way absorption is combined with cooling. If gases have to be removed from apparatuses operating in motion, care must be taken that the mechanical drive in the ventilation devices is connected with the apparatuses, so that the latter can be set in motion only together with the ventilation.

Washing, boiling, leaching, and similar operations, if their performance in closed apparatuses is impossible, must be carried out under double exhaust hoods connected

with ventilation. The second hood is arranged in such a way that between it and the lower one there is an opening of approximately 1–3 cm. In this way an air draft is formed between them, assisting the entrainment of the vapors that are given off and their removal.

In the present article we shall not touch upon the details of ventilation arrangements for removing gases and vapors from apparatus, since this is an entirely independent and complex question. We shall say only that the installation of such ventilation, especially in the institutions of which we are speaking, must be carried out by fully competent and experienced specialists. This circumstance is, unfortunately, often forgotten, and one frequently has occasion to see that ventilation installed by an inexperienced hand works poorly or almost not at all. In addition, before work is begun in an institution, its ventilation appliances must be carefully checked and tested, and their suitability and adequacy certified. Only in this way can all shortcomings be eliminated in good time and all unexpected contingencies avoided. In operations dealing with suspect material (such as, for example, the processing of animal carcasses), the requirements with respect to ventilation must be increased. In this case one cannot limit oneself to the removal of gases from the working apparatus; thorough ventilation of the entire room is necessary. At the same time, the ventilation of the room and the removal of gases and vapors from the apparatus must be carried out by entirely separate systems, so that one does not operate to the detriment of the other.

In arranging institutions for the processing of slaughterhouse refuse, the distribution of the separate working rooms plays no small role. Rooms for the storage of incoming raw material, and also for work during which unpleasant fumes occur, should not be placed on the sunny side, so that in summer the material does not become too heated and decompose prematurely. As a precaution in this regard, double windows with frosted or differently colored glass may be used. That the rooms for receiving and processing decomposing and malodorous materials must be completely isolated from the other workrooms goes without saying. Yet, strangely enough, this requirement is still very often not taken into account.

Hand in hand with the measures mentioned above, when arranging institutions for the processing of refuse, there must go a careful selection of apparatus. By this name one must understand devices for transport, working machines, and devices for

mechanical ventilation. All these devices must vary according to the nature of the work, but all of them must be required to be suited to their purpose, to operate easily and correctly, to be solidly constructed, and, when used, to guarantee complete safety for the working personnel and neighboring residents.

It must also be borne in mind that, in establishments for processing refuse, any stoppage of work leads to extremely undesirable consequences. Therefore, all measures must be taken in advance so that production does not have to be stopped because of repairs or a shortage of any parts. For this purpose there must always be a complete set of spare parts necessary for replacing steam boilers, machines, apparatus, etc., that have become unserviceable or are undergoing repair. It is also necessary that all production appliances be equipped with devices for preventing accidents, guaranteeing the safety of the working personnel.

Equally serious attention must be paid to the arrangement of rooms for the temporary storage of raw material. As has already been said above, one should, as far as possible, avoid storing refuse that is subject to processing and should endeavor to introduce it into the processing apparatus as quickly as possible. But if the conditions of production are such that the raw material has to wait for loading for some time, then it must be kept in special, completely closed rooms, the ventilation of which should be carried out by mechanical means, as mentioned above. In special cases, and especially in the hot season of the year, these rooms must be artificially cooled.

Stone receptacles must be arranged in such a way that they can be easily cleaned and washed. For this purpose they should, as far as possible, have smooth walls and be connected to the sewerage system. It is appropriate to recall here that, since the floors in these and other rooms where work is carried out, for the same reasons, must be smooth and therefore easily become slippery from contact with the substances with which one has to deal, all discharge and receiving openings must be fenced with high rims in order to prevent workers from falling.

Receptacles for receiving decomposing refuse must be of such size as to receive the refuse of only one day. In such cases it is still more expedient to use, for receiving the refuse, well-closing barrels, which, as they are filled, must be delivered to the place of processing. It goes without saying that in this case one must always have a reserve of barrels and means of transport in sufficient quantity. The delivery of refuse

Y. I. Nikolit.

to storage rooms, as well as their transport in general, must be carried out in well-closed devices (carts, elevators, etc.). Unloading of the material intended for storage must take place either in the room itself or in an annex specially adapted for this purpose and connected with the storage room.

In establishments for the processing of refuse it is very often necessary to have rooms for drying either raw material or products of manufacture. These rooms must be arranged according to the principles set forth above and provided with the same mechanical ventilation devices, so that all vapors, gases, etc., may be removed imperceptibly. Artificial ventilation is required here also because it shortens the drying process.

In addition to rooms intended specifically for work and, in general, for the various needs of production, in establishments for the processing of animal-rendering refuse there must also be provided, and suitably arranged, rooms for the needs of the working personnel. Such are rooms for changing clothes, for washing, for taking meals, and privies.

The working conditions in these establishments are such that the workers and persons of technical supervision must have the possibility of resorting to thorough washing. They need this more than any other category of workers. To give them the possibility of washing only their hands and face is far too insufficient; in the interests of health they must have the possibility, after finishing work, to wash the entire body thoroughly, in order to remove the bad odor and rid themselves of the risk of dissemination of pathogenic substances. Therefore, for the use of the workers, showers with warm water must be arranged in special sections, and, even better, baths. The management of a utilization plant must not only provide the workers with the use of showers and baths, but must also strictly require it, all the more so because workers accustomed to order and cleanliness will better understand all measures for maintaining cleanliness and hygienic conditions of production and will assist in carrying them out.

For the working personnel of a utilization plant, changing rooms are also necessary; these are best connected with the bath room. For changing into working clothes and into outdoor clothes there must be separate rooms. The most expedient arrangement is one in which, after finishing work, the worker removes his working clothes in a special room, from there proceeds to the bath, and then enters the place where, at the beginning of work, he removed his outdoor clothes. The room where the workers leave their working clothes must be arranged so that wet working clothes quickly

dry out. The changing room should be provided with good ventilation, but without drafts. It is appropriate to say here that work clothing should be state-owned and should be changed at least once a week.

For taking food (breakfast, dinner), special rooms should be arranged, furnished with tables, chairs, and benches, into which the workers should enter only after first thoroughly washing their hands and face. The provisions brought with them should be placed by them, before the start of work, in a designated place in the dining room. The maintenance in cleanliness of the showers, baths, changing rooms, and dining room should be entrusted to a person accustomed to cleanliness.

The privies for the workers of the utilization plant must necessarily be made warm, connected with the work premises by equally warm passageways, so that they can enter them without risking catching cold, which is very easy in this type of production.

VIII. Processing of slaughterhouse waste.

The question of processing slaughterhouse waste is divided into two parts, depending on the division of the objects of processing. By slaughterhouse waste, in the more general meaning of the word, are understood the following elements: the contents of the stomach and intestines, intestinal mucus, blood, organs not used for food, and also confiscated materials. Of these, the first two elements, when processed, being associated with considerable difficulties and inconveniences, ultimately yield products of little value, and therefore are much more often subjected to neutralization by removal from the slaughterhouses. For this reason, the name slaughterhouse waste, in the narrow sense of the word, applies to them chiefly. On the other hand, confiscated materials, which can be processed with greater convenience, yielding as a result more valuable products and therefore often subjected to utilization, are usually placed in a special category. These two categories also differ from one another with respect to the principal technical methods of processing.

Owing to these features, it seems convenient to divide the presentation of the methods for processing the above-mentioned elements into two parts, one of which will relate to the processing of slaughterhouse waste proper (in the narrow sense of the word), and the other to the processing of confiscated materials. Because of the similarity of the technical methods and of some of the products of processing, the utilization of blood may also be assigned to the first part. The utilization of organs not used for food, being no different from the utilization of confis—

cattle, belongs entirely to the second part. For the same reason, the utilization of the carcasses of fallen and slaughtered animals must also enter into this latter part.

We begin with an exposition of the methods of processing slaughterhouse wastes proper, to which the present section is devoted. In it, consequently, we shall deal with the processing of the contents of the stomach and intestines, intestinal mucus, and, in a few brief outlines, blood.

The processing of the contents of the stomach and intestines of animals has as its aim, first, while preserving in it the elements valuable as an agricultural fertilizer, to remove, as far as possible, all water as a useless admixture; second, in this way to convert these contents into a dry, light mass and to make possible their transport over long distances; and third, finally, in the course of the treatment to destroy any pathogenic elements that may be present in the material being processed.

The processing of these contents presents many technical difficulties, owing chiefly to the abundant content of water. The task is to remove 75–85% of water—a procedure that is possible only with large expenditures and that at first glance seems almost impracticable from an economic point of view, since the value of the contents of the stomach and intestines as fertilizer, precisely because of the large water content and the comparatively small quantity of readily soluble nitrogenous substances, is very low. On the other hand, the substances being processed are distinguished by an unpleasant odor, and therefore their treatment raises doubts from a sanitary point of view.

Nevertheless, this question is coming ever more to the fore, since the removal of wastes, as has been done hitherto, in an unchanged form is becoming increasingly difficult, especially for large cities. The reason for this lies in the fact that it is often not possible to use these wastes in the immediate vicinity, and they have to be transported over long distances. In such cases, as the distance increases, the costs of transport grow disproportionately. Moreover, the transport of untreated wastes is obviously unsafe, since pathogenic agents can easily be spread by it, and it may serve as a cause of cattle mortality. These economic and hygienic considerations, whether one wishes it or not, compel technology to continue its attempts to solve the extraordinarily difficult problem of processing the contents of the stomach and intestines.

At the present time, just demands are being voiced ever more frequently, with a view to preventing epizootics, that wastes, even when transported—

...raw without treatment; in any case they were first disinfected. For this purpose it is recommended, in small slaughterhouses and in general wherever the processing of waste has not been introduced, to disinfect it before removal by complete immersion in milk of lime. As regards large slaughterhouses, it seems desirable, in order to reduce the cost of transport, to process the waste completely into a dry, unalterable mass, i.e., into the form of powder. Many methods have been proposed for this purpose. Unfortunately, however, only a few of them can be considered satisfactory, especially from an economic point of view. We shall indicate some of these methods.

Schwarz recommended processing the contents of the stomach by adding a 2–3% solution of sulfuric acid, followed by boiling at a temperature of 100°, which is at times raised, and drying. By this method the microorganisms contained in the waste are completely killed, and the water-saturated mass is converted into a dry powdery product, which in any case has such value as to justify the costs of long-distance transport. However, the drying of the product in open vessels employed in this case leads, of course, to great inconvenience for the working personnel and the surrounding population, and compels one to regard this method as far from perfect.

Otto in Dortmund constructed, for processing the contents of the stomach and intestines, a drying apparatus consisting of two steam-heated boilers, in the middle of which rotates a bundle of tubes likewise heated by steam. This apparatus, however, was found unsuitable for operation, since the value of the products obtained did not justify the costs of processing, and moreover the processing process was accompanied by a very unpleasant odor.

Attempts were also made to apply centrifugal force to free the contents of the stomach from water. Experiments in this direction were carried out at the slaughterhouse in Viersen by von Ehrle. In these experiments it proved possible, within 7 hours, to reduce a mass of manure of 200 centners to half its weight. But even this method proved impracticable because of its laboriousness and high cost.

Dalge tried pressing the contents of the stomachs of ruminant animals into briquettes, drying them, and then burning them. The pressing was carried out in perforated iron boxes by means of a lever press. From each large head of cattle 18–20 briquettes were obtained. But here too it was not possible to achieve favorable results for the same reasons, and this method did not find application. More suitable for practical use proved to be squeezing...

of the manure mass between two rotating rollers. But this process can remove from the manure only 10–20% of the water, so that, in order to reduce the water content to the desired limits, a number of other operations is required.

By applying this last method, in connection with well-considered drying devices, the firm Venulet & Ellenberger in Darmstadt succeeded in designing and constructing, for the Munich slaughterhouse, an installation for processing the contents of stomachs and intestines, which proved to be truly practical and may serve as a model for other slaughterhouses.

Owing to the expansion of the city of Munich and the purchase of lands around the city for building, it became more and more difficult to apply to the slaughterhouse wastes the method of removal in the raw state, so that the municipal administration found it necessary to turn to the processing of these wastes. The task was a very difficult one, since positively none of the previously tried methods could be considered satisfactory, and a new solution had to be sought. But the Munich municipal administration, which for many years had shown a broad interest in every new undertaking, was not frightened by this task and, together with the firm Venulet & Ellenberger, successfully solved it.

The factory for manure powder of the Munich slaughterhouse is located in a window-lit basement of the gut-house and occupies an area of 1000 sq. meters (35 × 31 m.). The premises were selected with the calculation that the installation now in existence could, with the development of production, be doubled.

The contents of the stomach and intestines enter from above into collecting boxes a a a a (drawing 12), which are located in the floor of a wide passage left at the very end of the gut-house. From these receivers the contents, as needed, by means of tightly closing openings, are discharged into distributing Archimedean screws b b, capable of rotating both to the right and to the left; by means of them they enter the presses c c. In these presses, by means of specially constructed rollers, part of the liquid contained in the manure is squeezed out, so that the manure leaving the rollers contains no more than 80% water. The pressed material is conveyed by means of an inclined Archimedean screw d d into trough-shaped reservoirs with double walls e e, which are heated by the condensation water supplied here from the heating system of the drying apparatus. Inside the above-mentioned reservoirs there rotates a screw-shaped mixer, which very slowly conveys the manure from one end to the other. From here the warmed manure enters the Archimedean screws f f, which deliver it to the first drying apparatuses g g.

Destruction and Utilization of Slaughterhouse Waste

At the end of the latter, the half-dried material passes further into the inclined device hh, which transfers it into the second drying apparatuses ii. The drying apparatuses proper, gg and ii, are tightly closed reservoirs in which stirrers rotate, consisting of cylinders mounted on an axis with double walls, heated from within by fresh steam. They also contain a conveying device, by means of which the manure slowly moves from one end to the other, being simultaneously mixed, so that the dried product may be as uniform as possible. The dry warm powder passes from the drying apparatuses ii into the inclined cooler kk, with conveying devices, which carries it into the open cylinders ll. From there, finally, the finished product is raised into the packing department, entering, by means of a special device, directly into sacks of a definite capacity. All the apparatuses for preliminary heating, drying, and conveying are hermetically closed, so that no gases or unpleasant odors can escape outside. The gases formed in the apparatuses are first directed, by means of the gas conduit mm, into a settling chamber, where the dust particles carried along by the gases are deposited. Then the gases and vapors enter the spray condenser o, connected with the settling chamber. Here the vapors are condensed by water, while the gases incapable of condensation are drawn off by the electric exhauster p, forced through a duct beneath the furnace of the steam boiler, burned, and drawn out through a chimney 54 meters high. Above the packing apparatuses there is also a receptacle for sulfuric acid, so that, if necessary, the finished powder may be disinfected by adding this acid. The installation is served by a steam engine of 60 horsepower.

The product obtained as a result of the process described is a fine, almost odorless powder. It is sold in sacks weighing 30 kg each, at a price of 65 pfennigs per sack (including the cost of the sack, 25 pfennigs). The apparatus described above, at the Munich slaughterhouse, for treating the contents of stomachs and intestines has already been in operation for several years and, according to information from the municipal administration, there have never been any complaints or grievances concerning inconveniences caused by it.

Intestinal slime is the name given to the waste obtained in the processing of intestines. It consists of the mucous membrane of the intestines and the mucus separated from it, which is more or less contaminated with remnants of the intestinal contents. These substances, separated during the processing of intestines, decompose extremely rapidly, emitting a very unpleasant odor.

Fresh intestinal mucus consists of 90% water, 2½% fatty and 4–4½% nitrogenous substances. The cleaning of intestines from mucus, notwithstanding the fact that special machines exist for this purpose, is carried out almost exclusively with flat, trough-shaped sticks, usually in the intestinal departments themselves, and only in large slaughterhouses in separate rooms. The following exposition will therefore concern these special rooms and the processes connected with them.

Departments for cleaning intestines from mucus, unless the premises and equipment are chosen with particular care, cause many unpleasant conditions for residents and workers, over which one must reflect. Existing installations, unfortunately, can by no means be regarded as exemplary. Almost everywhere there is a lack of mechanical ventilation and of special arrangements corresponding to the production, so that the personnel working here are condemned to damage to their health as a result of dampness, unpleasant vapor, and stench. The odor given off often spreads far beyond the limits of the room.

In consequence of these circumstances, when arranging chambers for processing intestinal mucus, one must be guided with special attention by the considerations stated earlier concerning premises for subsidiary productions at slaughterhouses. For the premises of these chambers one should design large and high rooms connected with one another and provided with reliably functioning double ventilation. The work must be carried out, in the interests of the surrounding residents, with the windows closed. Workers must be placed in conditions of harmless residence in the chambers by means of an artificial supply of clean air. Hand in hand with these measures there must go the fastest possible removal of intestinal mucus from the room, which is best achieved by means of drainage channels flowing into the processing apparatus. These latter, of course, must also be connected with ventilation. The slops obtained during the work must be discharged into the sewerage system. Especially undesirable must be considered the long lying of the intestines, sometimes used in order to facilitate separation of the mucous membrane from the walls of the intestines. Separation of mucus under such conditions is, of course, accompanied by a disgusting odor, and meanwhile this aim is easily achieved by a simple and non-putrefactive method. For this it is sufficient to pour over the fresh intestines heated water with the addition of a small quantity of soda. After several hours, usually after one night, the separation proceeds easily and without excessive odor.

Destruction and utilization of slaughterhouse waste.

The foul odor and capacity for rapid decomposition of intestinal mucus make its processing very difficult. The method most often used at the present time, which by no means can be called perfect, is as follows. Since the removal of this material, which is distinguished by its foul odor and moreover contains 90% water, is both inconvenient and unprofitable, and since its use as fertilizer without other admixtures is impossible, it is subjected to sterilization and processing by concentration in open apparatus heated by steam. In this process the intestinal mucus gives off 80–85% of its water, and owing to this the mass being processed, at first entirely liquid, turns into a product having a dense consistency and less liable to decomposition. This product can conveniently be transported and used for fertilizing purposes. However, during the boiling process, of course, extremely foul-smelling gases are formed, the removal of which is difficult, and this method must be recognized as unsatisfactory. To this it must be added that it is also economically disadvantageous, since, apart from the high cost of production, the material being processed very quickly spoils the iron of the evaporating apparatus.

For the same reasons, the concentration of intestinal mucus in apparatus for processing confiscates (of which more below), which has been tried with similarly poor results, must be abandoned. In general, in A. Fischer’s opinion, on the basis of the results obtained up to the present time, it becomes clear that any processing of intestinal mucus by means of concentration, without mixing it with other substances, must be considered inadmissible in the interests of the surrounding population, and especially cannot be tolerated within slaughterhouses. If the processing of mucus by means of drying is at all possible, then apparently it can be carried out by adding it (in moderate quantity) to the contents of the stomach and intestines and processing it together with this material. The processing of such a mixture, according to experiments carried out with the above-described apparatus of Venuleth & Ellenberger, presents no difficulties.

The only method of independent processing of intestinal mucus which apparently leads to satisfactory results is Dr. Plönnissche’s method, by means of which this mucus is processed into feed cake. It consists in the fact that fresh mucus, just removed, is subjected to repeated washing with water at 30–50°C, whereby the substances capable of decomposition, for the most part proteinaceous, are removed, and there remains a clean product, free of odor, which can be dried and ground. According to experiments carried out,

this method proves quite satisfactory in the hygienic sense, if it is carried out in closed apparatus. In this case the runoff water is discharged into the sewer, and the gases formed during drying are led off for combustion. The product obtained by such treatment contains approximately 23.5% fatty and 43.5% nitrogenous substances and is quite suitable as a feedstuff. The economic aspect of this method, which is in principle very desirable, depends on marketing conditions and has not yet been fully clarified.

If, by this or another method, it should not be possible to achieve a more successful processing of intestinal mucus, then in any case the method of incineration is applicable for rendering it harmless. On the basis of successful experiments with furnaces for incinerating carcasses, this approach must in all respects be preferred to methods of compaction as they are practiced at present. For incineration, Kori’s furnace can undoubtedly be used successfully with minor changes in design, for example, if a chamber for drying the mucus is arranged above the inclined part of the furnace vault. In this case, of course, the latter should be mixed with an absorbent material, such as peat powder, sawdust, manure rich in straw, etc.

The quantity of an animal’s blood is on average about \(1/13\) of the total body weight. The quantity of blood flowing out at slaughter is considerably smaller, since part of the blood is retained in the meat and organs. According to Geissler, the quantity of blood obtained at slaughter, in percent of the total body weight, is equal to:

Animals	Blood obtained at slaughter, % of total body weight
horses	3.93–9.00%
cows	4.02–5.75%
calves	4.40–6.65%
sheep	4.37–7.56%
pigs	1.45–5.74%

This quantity of blood is subject to variation. Thus females and fat animals have less blood than males or animals of lesser fatness. At the Bremen slaughterhouse the following relation was obtained between the weight of the blood and the weight of the carcass:

Animal	Average carcass weight	Blood weight
horse	238.6 kg	25.0 kg
cow	254 kg	17.5 kg
pig	60 kg	3.5 kg
calf	77 kg	4.5 kg
sheep	21 kg	3.0 kg

On the basis of these figures and of data on the ratio between live weight and carcass weight, it is possible to calculate for a slaughterhouse with a definite volume of work the quantity of blood subject to removal or processing.

Blood obtained during slaughter should not in itself be considered a waste product, since it can be processed and, with a broad organization of slaughterhouses, is processed into valuable industrial products such as albumin, dietary preparations, etc. Under such an arrangement, only those parts of the blood that remain after the manufacture of these industrial products constitute waste. Such parts of the blood, by means of special treatment, can be used to obtain substances applicable in agriculture as feed materials or fertilizer. Often, however, especially where slaughterhouse production is small in scale, blood is not processed into industrial products, and then it (if it is not discharged with wastewater) is converted in its entirety into feed or fertilizing substances. The processes for obtaining these substances from blood or its residues are one and the same.

We shall not, of course, deal with the question of processing blood into industrial products, but shall consider only the processes of utilizing blood, or parts of it, as waste. The products of such utilization are chiefly feed materials: blood meal, consisting exclusively of parts of blood, and feed products prepared with an admixture of other substances to the blood (blood “guano”). It should be said, however, that the name “guano” is applied equally to blood meal. The conversion of blood into fertilizing materials, in view of its high value as a nutritive substance, is, of course, extremely uneconomical. It is used only in cases of the joint processing of blood with wastes of inferior quality, in apparatus adapted for the latter. We shall not touch upon this method of utilization here, and shall confine ourselves to the processes of converting blood or its residues into feed materials, blood meal and guano.

The most common method of utilizing blood is the processing of part of the protein substances contained in it into albumin, with the conversion of the remaining elements into blood meal. To clarify the nature of these residues, it is sufficient to say a few words about the process of their separation.

When processing into albumin, the blood of freshly slaughtered animals is collected in tin-lined vessels and taken to a special room (the blood chamber), arranged in such a way that the blood can settle without any shaking. Here the blood coagulates, and after some time the blood serum separates from the blood clots. The former separates out as a jelly-like, viscous, transparent liquid, while the blood clots settle as a layer of loose, dark—

of the red mass. The blood serum thus obtained is converted, by chemical purification and drying, into albumin, which is used in dyeing, wine-making, and other industries, and which at present has replaced the more expensive product formerly prepared from hens’ eggs. The precipitated blood clots, after being pressed in lattice-like vessels in order to separate the serum still contained in them, constitute the residue that is to be processed into blood meal.

The mass remaining after the separation of the blood serum may be subjected to drying on ordinary millstones with moderate, not too intense heating. The dark-brown substance thus formed, after grinding, is used as an admixture to animal feed. Such a drying process becomes somewhat inconvenient if it is carried out in a built-up area, especially if the blood arriving for drying is no longer quite fresh. Therefore it is necessary, first of all, to require that the resulting blood clots be subjected to drying as promptly as possible, and also that the vapors released be directed into a special conduit, then condensed, burned, and discharged into a chimney of sufficient height.

In a more advanced manner, the same operation is carried out in a special drying apparatus. This latter usually consists of a steam-heated cylinder with double walls, in which an axle with blades for stirring rotates. As a result, the material is continually loosened, which helps accelerate the drying process. The foul-smelling vapors and gases formed inside the cylinder are removed by an exhaust pipe, which adjoins an exhauster connected with a condenser, a furnace, and a smoke flue.

In the case when the albumin contained in the blood is not subjected to special utilization, it, together with the other solid elements of the blood, goes to be processed into blood meal. In this case, too, the process begins in the same way as before, with the separation of the blood clots from the proteins dissolved in the serum. Then the latter are separated by boiling in a closed boiler, in the form of a precipitate formed at the bottom of the boiler. This precipitate is combined with the previously obtained blood clots and subjected to the drying process. Here, however, in view of the rapid decomposition of the proteins and the odor released thereby, the operation can be carried out only in hermetically closed drying apparatuses.

Both for boiling and for the joint drying of the constituent parts of the blood, the above-mentioned ...

Destruction and Utilization of Slaughterhouse Waste

...the rotating drums described below, used for the thermal sterilization and utilization of confiscated materials and carcasses. For example, in the Hamburg slaughterhouse, blood is processed in Podewils’s apparatus. A single loading of the apparatus takes 1100–1200 kg of blood. The amount of meal obtained is about 18%.

The blood mass dried in closed apparatuses of one design or another is conveyed, by means of a likewise closed transfer device, into a roller mill. Here it is converted into the final product—a dry brown powder known as blood meal. It is used, as stated, as an admixture to animal feed (for pigs, dogs, fish). When 1000 kg of blood are dried, about 140 kg of meal are obtained.

The composition of blood meal may be judged from the analyses of the Hamburg City Laboratory given below.

Average for the year	Nitrogen	Protein substances	Phosphoric acid	Water	Fat
1896	11,825	73,906	1,663	8,29	4,14
1897	11,758	73,4875	1,776	12,06	6,58
1898	11,27	70,437	1,46	12,88	4,38
1902	11,56	72,25	2,16	7,57	6,78
1903	11,16	69,75	1,91	16,02	4,17

The inconveniences from the hygienic point of view that accompany the boiling of blood serum and the drying of the constituent parts of blood are the greater the longer the blood intended for processing has stood. Therefore one must always strive to ensure that the freshest possible material enters processing. But even under this condition it is necessary to require the most thorough arrangement of ventilation for the working apparatuses, as well as for the work premises.

By the name blood tuka is meant a dry fodder product consisting of blood mixed with other fodder substances, which usually likewise represent industrial waste. Such are rye, wheat, and buckwheat chaff, oat husks, waste from fodder bread, and in beet-sugar districts also so-called black molasses, a waste product of sugar manufacture.

In the manufacture of blood tuka, the work is reduced chiefly to the process of mixing and drying blood and fodder substances. An example is the preparation of blood-molasses tuka by the method of Clausen and Friedrichsen. Blood and black molasses enter...

into special vessels. The blood first enters a crushing apparatus, in which the blood clots are comminuted and mixed with blood serum. The blood fluid flowing out from there goes into a vessel situated below, where it is combined with molasses; by means of stirrers both liquids are turned into a homogeneous mass. The mixture thus obtained enters a third apparatus, where solid feed substances are added to it, such as ears or husks of cereal grains, grain screenings, malt, etc. The mixing apparatus consists of two shafts moving side by side, with blades arranged in a screw-like fashion. The solid substances intended for absorbing the mixture of blood and molasses enter through a funnel at the beginning of the apparatus. As a result of the motion of the shafts, the materials are mixed and gradually move from one end of the apparatus to the other. The result is a viscous, gruel-like mass. From the mixer it enters a drying apparatus heated by steam. This apparatus dries the material and, bringing it to 100°C, at the same time sterilizes it. The dry product then passes into a crusher and a sieve, from which it emerges in the form of a dry powder, constituting an excellent, very nutritious feedstuff. Sometimes the process is conducted in another order, first mixing the molasses with the absorbent substances and then enriching this mixture with blood. For this purpose the coagulated blood is comminuted in the blood crusher and then enters the mixer for combination with the other substances. After this the drying of the product is carried out in the previous manner. It must be said that in the manufacture of feed meal vapors are also released that are distinguished by a very unpleasant odor. Therefore here, too, it is necessary to recommend the most serious attention to the question of ventilation of the apparatus and workrooms.

IX. Sterilization and processing of confiscated materials and animal carcasses in rendering boilers and digesters.

By the term “confiscated materials,” in the narrow sense of the word, are understood those organs or parts of animals, as well as whole carcasses, which, upon examination by veterinary supervision at slaughterhouses, have been recognized as infected, suspicious in respect of infection, and in general dangerous for use, and therefore subject to confiscation for the purpose of disinfecting them in one way or another. Since, when applying these forms of destruction or utilization, the fate of these elements is shared by certain animal organs that are not generally used for food, in practice the latter too are brought under the concept of confiscated materials. Finally, confiscated materials are called

also the carcasses of animals deemed suspicious and killed by veterinary supervision, subject to destruction or disinfection, as distinguished from the carcasses of fallen animals. The principal characteristic of confiscates is the actual or presumed presence of an infectious agent, which makes disinfection necessary and permits utilization only on condition of simultaneous rendering harmless of the material being processed and complete safety of the processing operation.

The methods of rendering confiscates harmless are:

a) burial in the ground, with appropriate precautions;
b) burning;
c) dry distillation;
d) boiling down;
e) treatment with high-pressure steam;
f) treatment with mineral acids.

We have discussed in their proper place the methods of destruction by burial in the ground and burning, and the shortcomings connected with them. The remaining methods have in view not destruction, but rendering harmless and at the same time obtaining useful products that have application in technology and in agriculture. It must be said, however, that dry distillation of confiscates (with chemical reagents, for obtaining organic compounds used in industry) has so far proved to be not very profitable and therefore has not become widespread. The method of simple boiling down presents considerable inconveniences and is inadmissible in well-organized institutions. Of more serious importance are the methods of treatment with high-pressure steam and with mineral acids. The latter, however, the chemical method of utilization, is applied on an extremely limited scale, whereas their thermal processing by means of steam is gradually developing. This undoubtedly depends on the fact that the process of steam treatment is simpler and more convenient than treatment of the material with acid and the other operations connected with it. Therefore the latter method, although it is sometimes no cheaper than chemical treatment, has almost completely displaced the latter and is in general the dominant one in modern utilization plants. Thus we may quite properly devote the following exposition chiefly to the method of processing confiscates by means of high-pressure steam, limiting ourselves to brief information concerning the other methods.

An institution in which sterilization and processing of confiscates is carried out by one or another method is called, as was indicated, a utilization plant. We said earlier that under modern—

in methods for rendering slaughterhouse refuse harmless, it seems possible to place installations for such neutralization in the closest connection with slaughterhouses. This principle is also applied in practice to devices for destroying refuse and condemned materials by incineration, which are arranged directly within the limits of slaughterhouses. As for rendering plants, their direct connection with slaughterhouses is likewise practiced, but considerably more rarely. This is explained, first, by the fact that, although there is undoubtedly the possibility of conducting the processes for treating condemned materials in an entirely faultless manner, the attainment of such ideal faultlessness depends on the efforts and attention of the institution’s personnel, and therefore there is always a certain uncertainty that leads one to prefer arranging institutions of this kind separately. A second, more definite reason is that rendering plants are often intended for the processing not only of condemned materials but also of the carcasses of fallen animals, and the admission of this latter material onto slaughterhouse grounds is inconvenient. It must be said, however, that locating a rendering plant too far from the slaughterhouse has its own inconveniences—quite apart from the additional costs of transporting the material—from the sanitary-police point of view, since some portion of the condemned materials may easily be put into circulation on the way to the plant, which happens quite often despite all precautionary and control measures. Thus the question of the location of a rendering plant is resolved differently, depending on local conditions, the material, and the perfection of the equipment. For the majority of cases, the most convenient arrangement is a separate location, but at a short distance from the slaughterhouse. In those cases where the plant is intended for processing only condemned materials, it is permissible to place it on an adjacent plot.

It has just been mentioned that at modern rendering plants the joint treatment of both condemned materials and the carcasses of fallen animals is often carried out. This is quite natural if one takes into account that in both cases the objects of treatment are technically identical elements, differing from one another exclusively from the sanitary point of view. In fact, condemned materials differ from the carcasses of fallen animals by the presence—at least presumed—of a contagious origin, but, on the other hand, they are free from the products of putrefactive decomposition. Conversely, carcasses, safe with respect to infection, are almost always more or less affected by the process of decomposition, which causes appreciable inconveniences in handling and processing them. The sanitary differences between materials of the one and the other

Destruction and Utilization of Slaughterhouse Waste

compelled people to draw a distinction between them also in the methods of rendering harmless, so long as these methods were primitive in character, since utilization could be permitted only with respect to the carcasses of fallen animals, while confiscated products were subject to destruction. At the present time, with the use for processing of apparatuses that guarantee complete rendering harmless and are hermetically sealed, and of devices that reduce the danger of handling infectious material to a minimum, both confiscated products and carcasses may be subjected in exactly the same way to sterilization and utilization by means of thermal (or chemical-thermal) treatment. The only distinction that has remained between them in this respect consists in the fact that, in applying this to confiscated products, no special utilization of the more valuable elements—skins, hair, bones—is allowed, and it is recommended that they be processed as whole carcasses, without division into parts. In addition, as a precaution, a distinction is made in the use of certain products of processing obtained from confiscated products and from the carcasses of healthy animals.

In any case, with the modern organization of the matter, the rendering harmless and utilization of both confiscated products and animal carcasses is carried out by the same processes, in the same apparatuses and utilization plants, very often jointly. Even if there are cases of utilization of materials of one kind or the other in separate institutions, this is in any case not for technical reasons, usually not even for sanitary reasons, but for purely economic considerations. Therefore, in further considering the question from the technical point of view, we have every right and basis to speak throughout of the rendering harmless and utilization of both kinds of material simultaneously and without distinction, understanding by the object of treatment carcass material—both confiscated products and the carcasses of fallen animals. By way of exception, it will be necessary to understand the difference between them only at the very beginning, when describing primitive methods of utilization.

Here, incidentally, let us recall that in apparatuses for the utilization of confiscated products and carcasses, various other solid wastes of animal origin—pieces of meat, hides, etc.—as well as blood and intestinal mucus, may be processed together with them; and such a combination is natural and customary.

The rendering harmless and utilization of confiscated products and animal carcasses is currently carried out in various apparatuses, ranging from simple tallow-rendering boilers to modern, technically perfected and rather complex devices known under the general name of universal utilization apparatuses,

combinations of which constitute properly organized and, not infrequently, extensive utilization plants. In proceeding to describe the apparatus and processes used for the stated purpose, we may conduct the discussion in the order of the technical development of these apparatuses, beginning with the primitive and ending with the most complex and perfected. Such an order will, of course, also correspond to the historical course of the development of the matter. Thus we shall consider, in sequence, first of all the boiling down of confiscated materials and carcasses in rendering kettles and digesters, then treatment in so-called disinfectors, and, finally, in universal utilization apparatuses.

Awareness of the economic value of the individual elements of animal carcasses and the desire to make use of them have always existed. This desire, however, encountered obstacles, on the one hand, in the limits of the technical means for utilization, and on the other—in sanitary considerations. The most ancient and most widespread method of utilization was the use of the hides, hair, horny parts, and fat of dead animals. Considerably later there began to be employed the utilization of the carcasses themselves, at first incomplete, by primitive methods, and then ever more perfected. Of course, utilization by means of the simplest methods had to be limited (at least by law) to the carcasses of fallen animals that were safe with respect to infection, until the improvement of apparatuses and processes provided a guarantee of complete disinfection in the course of processing any infectious material.

The primitive methods of treating the carcasses of fallen animals reduce to boiling down and steaming out (more properly, steam-rendering). Boiling down, in its simplest form, is carried out in open so-called rendering kettles. Parts of the dissected carcass are placed in such a kettle, filled with water, and boiled directly over a fire. In this process, on the one hand, fat is obtained from the fatty tissues in a form convenient for sale; on the other hand, the boiling process makes the bones more convenient for further processing; moreover, malodorous substances are destroyed to a considerable extent. This method, used in many old-type knackeries, is usually improved by placing the carcass material in a kind of grate, which is inserted into the kettle and removed from it with the aid of a crane. The fat that separates during boiling and remains on top is skimmed off, while the remaining meat broth is used for fertilizing fields or is removed. The boiled meat parts, mixed with lime or without it, are used as fertilizer, and the bones may go for processing.

Of course, this method of boiling is extremely imperfect from a sanitary standpoint, because, when heated only to 100°C, one cannot vouch for the complete killing of pathogenic germs, and, moreover, the process is accompanied by vapors of an extremely unpleasant character.

Therefore, in large and more well-equipped institutions, instead of open rendering kettles, closed iron vessels are used, furnished with an internal grating or perforated bottom, up to 2–3 meters high and up to 1.5 meters in diameter, heated by steam introduced inside. They are filled through a hatch at the top and are provided on the front side, above the internal bottom, with another hatch for removing the residues after treatment; both hatches are hermetically closed. A steam pipe passes through both bottoms, opening above the perforated bottom; and, for the discharge of gases and vapors into a condenser, there is an outlet pipe in the upper cover. Pipes are also provided for admitting water and discharging the liquid products of treatment. Such vessels are clad with wood or walled in, in order, as far as possible, to limit heat loss. When boiling down in these closed kettles, the material is subjected to the action of steam at low pressure, and the contents are heated to 110–120°C. In this process the separation of fatty and gluey substances takes place in somewhat greater quantity. At the end of the process, these substances are led off into a special receiver, where they separate owing to the difference in specific gravity. The advantages of this method of boiling down, as compared with the preceding ones, amount, on the one hand, to acceleration and greater productivity of the actual working process, and, on the other, to the elimination of unpleasant odors and the destruction of more resistant germs of pathogenic organisms.

Methods of treating cadaveric material by boiling down remain, up to the present time, very widespread, owing to their simplicity and the cheapness of the initial installation. But they have general shortcomings, of which the first consists in the fact that the residues of bones and meat are not dried in the apparatus and are not fully freed of fat, so that, upon leaving it, they must still be dried either in special devices or in the air; in the latter case a strong stench inevitably spreads. Further, a large quantity of rapidly decomposing meat broth, formed during the boiling, is extremely burdensome; its discharge into water is impossible, into the ground inconvenient, and its use for agricultural purposes impossible until a fairly long time has elapsed.

Therefore, almost everywhere where there is a serious desire to put the matter on a satisfactory footing, they are now turning to more advanced methods of utilization. All these methods, to a greater or lesser degree, amount to rendering in apparatuses of various construction, ranging from very simple ones to more complex and advanced ones. The simplest apparatuses for treating cadaveric material by rendering are known under the names of digestors (Digestoren) or high-pressure meat renderers (Hochdruckdämpfer). Such an apparatus consists of a vertical cylinder, riveted from iron sheets, which is charged from above, while in the lower part of the wall there is a hatch for removing the solid residues of treatment. At a small distance from the lower bottom of the cylinder there is another perforated bottom, which supports the charged material and allows the substances extracted by rendering—the fat and glue liquor—to flow downward. To the very lowest part of the bottom of the cylinder is attached a pipeline, which is closed by a valve and serves for the removal of the liquid products obtained. The live steam is introduced from above. Several such cylinders are often connected into one battery, with the liquid products of treatment from the discharge pipes entering a common pipeline, and the pipes bringing in steam being supplied from a common steam line. Heat loss is limited, as far as possible, by appropriate insulation of the individual cylinders. Sometimes the cylinders are made with double walls, so that the space between them, served by a steam line, acts as a steam jacket. An improvement is also often found with respect to the introduction of the steam. Instead of simply admitting steam through an opening in the upper cover, it is led through pipes downward to the place where the material is located and released through small openings or branch tubes in the form of jets that penetrate the material and act more uniformly on its separate parts.

The operation of such an arrangement is very simple. The individual apparatuses are filled from above with the material to be treated; then the hatches are hermetically closed, and the admission of high-pressure steam, at 3–4 atmospheres, begins. The liquid products released under the action of the steam—the fat and the meat and glue decoction—accumulate beneath the perforated inner bottom and are from time to time discharged through the pipeline, so that the fatty substances do not remain too long under the action of the high temperature, which affects their quality. The time when all the fat that can be obtained by this method has been extracted from the treated material is determined on the basis of samples from the discharge pipe. Upon the arrival of this moment,

all the liquid products remaining in the apparatus are removed by steam pressure, the discharge tap is closed, and the solid residues are taken out through the side manhole.

The liquid products obtained from the discharge pipe are collected in a special reservoir and in a short time separate into glue liquor and fatty substances floating on top. This separation, however, is not so complete that it can be considered satisfactory, since a greater or lesser quantity of fat is always still contained in the glue liquor. For the final separation of the latter, this liquid is directed into a special iron vessel with double walls, heated by steam. Owing to the heating, the glue liquor remains in a liquid state, and the particles of fatty substances remaining in it can freely rise to the surface. Upon completion of this process, all the fat is skimmed off, and the residue is sent for evaporation and drying, which in its simplest form is carried out in special shallow vessels. Among the products of processing, the fatty substances, after cooling, go in the form of tallow for the manufacture of soap or for lubricating materials; the solid meat residues, after drying and grinding, constitute a fertilizing meal; the bones go for processing, and the mass obtained from the glue liquor is used for preparing lower grades of glue. In practice, however, the utilization of the glue liquor rarely proves productive, and often the latter is simply subjected to removal and destruction.

About 20 years ago, evaporators of the type just described, originally used for processing bones, were first applied for utilizing condemned materials at the slaughterhouse of F. W. Stock in Düsseldorf. The method of carrying out the work differs in no way from that described by us. After evaporation is completed, the liquid products are discharged into a barrel, the fat is skimmed from them, and the remaining glue liquor is usually collected in a special pit for putrefaction and then used as fertilizer. The solid residues are removed from the apparatus through an opening in the perforated bottom located above, dried in open dryers, and finally converted into powder by a roller mill.

The meat meal thus obtained is yellowish-white in color and, according to analysis, has the following composition:

Component	Content
Nitrogen	6.74%
Phosphoric acid	15.84%
Fatty substances	10.16%
Dry matter	94.46%
Ash	40.12%
Organic substances	54.34%

A product of similar origin, which after grinding was further subjected to the action of sulfuric acid, had the following composition:

Component	Content
Nitrogen	6.66%
Phosphoric acid	15.62%
Fatty substances	10.39%
Dry matter	94.23%
Ash	38.74%
Organic matter	55.49%.

Such digesters are still used exclusively in the processing of refuse at the slaughterhouse of the “Joint-Stock Company of Liebig’s Meat Extract” (Liebig’s Extract of Meat Company Lim.) in the city of Fray-Bentos in Uruguay. In the course of time, production at this gigantic abattoir has been organized in such a way that practically nothing is wasted there. Everything that does not go into the manufacture of the extract is dumped, together with pieces of hide, hooves, and bones, into 18–20 so-called tinas, enormous high-pressure evaporators about 10 meters high and 3 meters in cross-section. The evaporation of the collected raw material in the tinas takes place with the addition of a small quantity of water and by means of steam at a pressure of 4 atmospheres. After approximately 6 hours of operation the introduction of steam is stopped, and instead water is introduced into the tinas from below. The water drives the fatty substances upward, so that they come out of the upper opening for filling the apparatus and, by means of special gutters, run directly into large reservoirs. Here the fat floating on the glue broth is skimmed off, while the remaining liquid is let down into a very simple device for separating the fatty particles still contained in it in large quantity. This latter device (the so-called ladron) is a large fat trap in the form of a brick basin about 10 meters long, 3 meters deep, and 4 meters wide, divided along its length by several transverse walls that do not reach either the top or the bottom of the basin, alternately.

The solid product remaining in the tinas, naturally much reduced in volume as a result of evaporation, is removed by means of hooks through openings and sent on wheelbarrows or small wagons to a centrifugal machine for extracting the fat contained in it. Then follows the drying of the masses freed from fat, either directly in the air or in special drying rooms, and finally the dried product is ground in mills. The result of this part of the production is a fertilizer ...

…fertilizer, a fine, powdery material containing about 6% nitrogen and about 20% phosphoric acid, which is exported to Europe. Tallow is used as a lubricant on railways. Even the liquid meat-and-glue broth flowing from the tinas and ladron is utilized in a very peculiar way—although one far from impeccable from the sanitary point of view. In a small bay of the Uruguay River, into which the wastewater channel carrying it empties, schools of fish circle throughout the slaughtering season, feeding on the substances contained in this waste. Abundant fishing is carried out there daily, and the products of the catch are processed to obtain gas that illuminates both the slaughterhouse and the entire factory at night. Thus, in this gigantic enterprise, absolutely everything is utilized, and nothing is wasted or left unprocessed.

The methods described above for treating animal material by digestion in digesters have serious advantages in comparison with the boiling method. Besides the obligatory use of tightly closed apparatuses, the treatment here is carried out at high pressure and temperature, thanks to which the process proceeds more intensively, requires less time, and thereby yields more perfect results. Further, the temperature of 140–150° C developed in the apparatus guarantees the destruction of the most resistant germs of pathogenic microorganisms and a more complete disinfection of the material. Finally, the use of steam alone for treatment, without adding water or with its use in only a small quantity, reduces the amount of glue liquor discharged and, by preserving a thicker consistency of this product, makes possible its further processing or at least facilitates its removal.

However, the construction of digesters does not eliminate the most essential drawback inherent in them as well as in boiling apparatuses. The point is that after treatment in them one obtains, apart from fat, only semi-products: on the one hand, residues of semi-dry meat and bones, and on the other—a meat broth, more commonly called, according to the properties of its principal constituent part, glue liquor. The first of these semi-products must then be dried in special apparatuses or in the air and, finally, crushed and ground by means of special devices (mills), and only after this is the finished product obtained—meat-and-bone fertilizer. The most unpleasant aspect of this, besides the division of the processing, is that the semi-finished product has to be transferred from one apparatus to another, which inevitably leads to the spread of extremely unpleasant odors.

As for the second by-product, the glue liquor, it can be processed, by thickening and drying, into glue. However, the product obtained from it is of poor quality, owing to the fact that the material contains too large an amount of dissolved meat parts. This liquor decomposes very rapidly and also gives rise to odors that are extremely undesirable from a sanitary standpoint, both during processing and especially when it is transferred from the apparatus. These shortcomings often force plants working with digesters and similar apparatus to abandon the utilization of glue liquor and resort to discharging it into the ground or into water.

X. Sterilization and processing of confiscated materials and carcasses in disinfectors.

From the foregoing we see that the operation of processing confiscated materials and carcasses is in every case reduced to four operations of different kinds: rendering the fat, removing the glue liquor, drying the semi-dry residue of bones and meat, and, finally, grinding the dried substances into powder.

The principal shortcoming of apparatus of the digester type consists in the fact that these four operations are separated from one another. The rendering of the fat is carried out in the main apparatus. The remaining glue liquor must necessarily be removed from this apparatus, whatever is subsequently done with it. The drying of the solid residue is carried out separately. Finally, crushing and grinding require a separate apparatus. From this arise inconveniences in two respects. First, some of the processes carried out in the open air are extremely unpleasant—namely, the transfer of the by-products from one apparatus to another, the drying of solid residues in the open air, and the handling of the glue liquor. On the other hand, the necessity of using several apparatuses complicates the work and makes production more expensive.

It is therefore not surprising that, after this, a number of attempts appeared to combine, as far as possible, all the apparatuses and processes into one. There were quite a few such attempts and, indeed, some of them ultimately led to devices that met their complex purpose. They are therefore called utilization apparatuses and, in contrast to those that utilize carcass material only partially, are also called universal. The first, but very serious, step in this direction was the invention of devices which, while preserving the separate nature of the processing,

allow the initial drying to be carried out in the apparatus itself and, in general, improve the handling of the semi-products. They are called disinfectors.

The first apparatus of this type, sufficiently developed and satisfactory for its purpose, was invented by De la Croix and installed at the slaughterhouse of the city of Antwerp in 1884. It is known under the name of the De la Croix-system disinfector, or the De la Croix, Willaert and Co. sterilizing and drying apparatus (Appareil stérilisateur désiccateur système de la Croix, Willaert et Cie.).

The apparatus consists (fig. 13) of three separate vessels A, B, and C, connected with one another by pipelines. The left half of all three vessels is shown in section, while the right half presents an exterior view. The vertically mounted cylinder A, provided with a steam jacket—the disinfector or sterilizer proper—is tightly closed at the top by a removable cover and serves to receive the material to be processed: whole carcasses or parts of them. Cylinder B is a receiver in which all the liquid portions extracted from the raw material collect: fat and glue liquor; cylinder C serves as a condenser for the gases and vapors issuing from cylinders A and B. By means of pipes b and c, sterilizer A is connected with the steam boiler; pipe b of the steam jacket heats it, while pipe c conducts steam into the apparatus by means of three branches, closed by valves, d, e, and g. From valve e a ring-shaped pipe f with openings for the escape of steam goes into the cylinder. The latter passes through the inner perforated bottom a and rests on support h.

From the upper and lower points of sterilizer A two pipes branch off, equipped with valves i and k, which join into a single bent pipe s entering receiver B. Communication of the receiver with condenser C is effected by means of a non-closing pipe t, the end of which, bent in a semicircle, is fitted with small holes and immersed in the water-filled space of the condenser. From the upper part of the latter a pipe z leads to the furnace of the boiler, where the gases are burned. In the apparatus described, the arrangement of both vessels B and C is quite similar. Both are provided inside with perforated boxes for spraying cold water, n and u, and on the side with water-gauge glasses o and v. Receiver B has, in addition, in its lower part a cock q and a valve r for emptying, and at approximately one third of its height a special outlet cock p. Condenser C is provided only with cock w and valve x for emptying. Sterilizer A has, above the perforated bottom, an easily opened aperture through which the solid residues of the treatment are removed. To make access possible to the valves and screws situated above human height—

In the upper part of the apparatus there is a platform surrounding the apparatus and provided with a ladder. The heavy cover of sterilizer \(A\) is suspended from a crane and, after the fastening bolts have been unscrewed, can be moved aside, after which the upper opening becomes free for receiving the material. The loading of the raw material is carried out by means of suspended boxes moved along beams on rollers with the aid of a winch with a chain.

The procedure for carrying out the work with Delacroix’s disinfecter is as follows. Having removed the cover of sterilizer \(A\) and, with the aid of crane \(F\), moved it away from the opening of the apparatus, one proceeds to load it with material. At this point it is necessary to see to it that all the soft parts (viscera), which during sterilization easily become compacted into dense masses poorly accessible to steam, are distributed as evenly as possible among the parts of the carcasses. If the question is the processing of such soft parts, then in such a case it is recommended to counteract their compaction by using wooden spacers, etc. Sometimes the processing of whole carcasses without dismemberment is permitted.

After the disinfecter has been filled, the opening is hermetically closed with the cover, and the heating of the apparatus is begun by means of steam admitted through valve \(b\) into the steam jacket. In this process the masses inside the disinfecter, under the action of dry heating, give off part of the water contained in them, which turns into steam. Simultaneously with the admission of steam into the steam jacket, valves \(i\) and \(k\) are opened; through them the air contained in the disinfecter and the gases released from the meat parts are removed. The principal significance of this warming, lasting from 30 to 60 minutes, consists in the fact that the steam subsequently acting upon the meat masses encounters material already preheated in advance and thus can immediately achieve its full effect without condensation.

After sufficient warming, valves \(g\), \(e\), and \(d\) are opened, and the process of the direct action of the steam begins. It goes without saying that even now, when the steam enters directly into the interior of the apparatus, valves \(i\) and \(k\) must be open so that the air still contained in the apparatus can be freely removed. At the same time the water injectors \(u\) and \(n\) are put into operation, in the form of condensation of the steam entering vessels \(B\) and \(C\). After several minutes have elapsed, valves \(i\) and \(k\) are closed, and the process of steaming and disinfection under the action of steam coming from the boiler begins. Now the steam in the completely closed vessel \(A\) very soon reaches the same pressure as in the steam boiler, approximately 4–5 atmospheres, and a temperature of about \(153^\circ\)—\(160^\circ\) C. Under the action of the steam, fat, gluey parts, and water are gradually extracted from the material being treated; they flow downward and collect beneath the perforated bottom \(a\).

Depending on the quantity and properties of the material, evaporation continues for from 6 to 12 hours. After this time has elapsed, the treatment is stopped by closing the steam valves \(b, d, e, g\), while the valve \(i\) is slightly opened. The steam pressure in the sterilizer is sufficient to force out all the liquid products collected under the sieve through pipe \(i\) into the receiver, where at the same time the injector \(n\) is opened for condensing the vapors passing over and escaping from the hot liquid. Vapors not condensed in receiver \(B\) proceed further through pipe \(t\) into condenser \(C\), and here are finally destroyed by means of injector \(u\). Gases insoluble in water are led through pipe \(z\) into the furnace of the boiler, where they are rendered harmless by combustion. Depending on circumstances, after the liquid has been distilled off, the steam valve \(g\) may again be opened for a time, in order finally to remove from the sterilizer the remaining liquid products. Sometimes these products are also drawn off into several receivers during the steaming process.

Upon completion of the preceding process, the hatch located above the perforated bottom is opened in order to empty the apparatus. The boiled solid residues prove to be completely disintegrated, not even excepting bones, and so softened that they can be crushed by hand. Even teeth and hard tubular bones are broken without any difficulty. In this condition the material still contains moisture amounting to 15 to 20% of its original weight, so that it must be dried before grinding. For this purpose special drying cabinets are arranged, the walls, upper and lower bases, and some shelves of which are made of steam pipes. The thoroughly dried material is first subjected to coarse comminution by means of a crusher, and then is converted into powder in a special mill.

In receiver \(B\), after several hours have elapsed, separation takes place between the fat and the glue liquor, and the fat is discharged through taps \(p\) and \(q\). The glue liquor is either thickened by evaporation, or, more often without treatment, is discharged through tap \(r\) directly into the sewer.

The Delacroix system was taken as the basis of an apparatus constructed by the firm Rietschel & Henneberg in Berlin, which differs from its prototype by certain improvements. This apparatus bears the name of the Kafill-disinfector of Rietschel & Henneberg (Kafilldesinfector*) von Rietschel &. Henneberg).

) The words Kafel, Kafill, Kafeller, or Kafäller have been used in the German language since the seventeenth century to designate knacker’s-yard work and workers, and are derived from the ancient Hebrew kefal*—to flay.

As Fig. 14 shows, in this apparatus the sterilizer \(A\) is arranged in such a way that into the upper part of the cylinder, intended for receiving the raw material, there is inserted a second cylinder with perforated walls, so that between the two cylinders an annular intermediate space 2 cm wide is formed. In the inner cylinder there are also inserted double cylindrical perforated partitions made of sheet iron, which divide the interior of the apparatus, and with it the material being loaded, into concentric layers 20–25 cm thick. The consequence of such an arrangement is that the steam admitted into cylinder \(A\) through valves \(v_1\) and \(v_3\) can act on the material filling the cylinder both through the gaps between the perforated partitions and through the outer surface of the perforated cylinder. In this way the time required for complete sterilization, separation of fat, and drying is considerably shortened. According to the experimental data of the firm Rietschel and Henneberg, complete steaming of meat and bones requires 5–6 hours, and of other organs and viscera—from 6 to 7 hours, so that two charges can be processed in a day. Recently it has turned out that, if there is no need for rapid operation, it is not at all necessary to admit steam continuously into the interior of cylinder \(A\). The objective is achieved equally well if only the steam jacket is heated by means of \(v_2\), after cylinder \(A\) has been properly freed from air through valve \(v_4\), and the material is heated for half an hour directly, in order to drive off the water contained in it. Under such conditions sterilization and extraction take place in the same way as with the direct action of steam. Moreover, if the outer surface of the steam jacket is properly insulated, a considerable economy of steam and, consequently, of fuel is obtained. As the fat and glue liquor collect in the lower part of cylinder \(A\), they are periodically, by opening valve \(v\), distilled into receiver \(B\).

Instead of the single receiver found in the Delacroix disinfector, the Rietschel and Henneberg kafill-disinfector has two of them (Fig. 14), or, more precisely, receiver \(B\) is here divided into two compartments lying one above the other. This is done in order to make it possible for the fat, after its extraction from the material, to separate and clarify as quickly as possible. With the installation of two receivers lying one above the other, this objective is achieved entirely independently of subsequent production. The first portions of the liquid product are admitted into vessel \(B_1\), and then, after separating \(B_1\) from \(A\), the fatty substances are allowed to separate from the glue liq—

bones under ordinary pressure, for which no more than two hours are required. Then valve $h_1$ is opened and the glue liquor is discharged into $B_{\mathrm{II}}$. The fat remaining in $B_{\mathrm{I}}$ is then released in a form ready for sale. If it is intended to obtain fat of especially good quality, one may use, for washing it, the injector $w$ and, for reheating, the steam coil—placed somewhat above the bottom and fitted with valve $v_5$. The water used in this washing is discharged into the sewer.

When the glue liquor has been collected in receiver $B_{\mathrm{II}}$, valve $h_1$ is closed again, and the steam jacket of the receiver is heated by opening valve $v_6$. The water of the glue liquor is converted into steam and led through $v_8$ into vessel $C$, where it condenses. Evaporation continues somewhat longer than the boiling-out in $A$, so that after the sterilizer $A$ has been emptied and the dry material removed, the thickened glue mass can immediately be discharged through valve $h_2$.

Condenser $C$, in comparison with the above-described construction in Delakrua’s disinfector, has also received a certain modification. It is equipped with a device that prevents water from entering from $C$ into $B_{\mathrm{I}}$ when the pressure in the latter is reduced. The gases formed during the concentration of the glue liquor smell very bad, and therefore vessel $C$ is connected with the sewer by means of a siphon. If the path required for carrying the gases that have not condensed in the condenser to the boiler furnace is too long, then, for burning these gases, a special small furnace is installed, heated with coke or gas.

As regards the duration of all the successive operations of treatment, the city engineer in Breslau, Rimmler, gives, on the basis of precise experiments carried out by him at the time, the following figures, which, in addition to steaming the material, also relate to the filling of the apparatus and the final treatment of the products.

No.	Operation	Time
1.	Filling the apparatus	$1/2$ hour
2.	Heating the material	$1/2$ hour
3.	Steaming	$7^{1/2}$ hours
4.	Distillation of glue water and fat into the receiver and emptying the apparatus	$1/2$ hour
5.	Transferring the meat residues into the drying apparatus	$2$ hours
6.	Drying	$10$ hours
7.	Grinding the dried mass	$1$ hour

In Fig. 15 is shown a plan of an expedient arrangement of the devices belonging to the Rietschel and Henneberg rendering-disinfector,

as it is recommended by the firm. All the rooms are arranged on one level and are distributed as follows:

I—room for storing the raw material and preparing it for processing;

II—machine room, in which are located: a steam boiler, a steam engine, and a Caffil disinfector with all accessories;

III—room for the warehouse of finished goods and for the purification of fat;

IV—room for drying and grinding the solid residue.

The separate apparatuses are designated as follows:

A—sterilizer of the Caffil disinfector.

B—receiver of the same.

C—condenser of the same.

a—wooden vat, lined with tin, for keeping the material in the disinfecting liquid;

b—vertical steam boiler;

c—horizontal steam engine;

d—workbench with a vise;

e—winch for moving boxes with material;

f—vessels for purifying fat;

g—mill;

h—room for coal;

i—box on wheels, serving for filling sterilizer A.

k—drying apparatus with steam heating.

The apparatus of the Delakrua system attracted the attention, among others, of Russian specialists, namely Messrs. Neishtube and Voevodskii. Mr. Neishtube, having acquainted himself with the apparatus, found it suitable and undertook to begin introducing it in Russia, for which the inventor himself, who wished to obtain a privilege for his invention, had requested him. On Mr. Neishtube’s initiative, engineer V. G. Voevodskii, city technician at the Petersburg slaughterhouse, entered into relations with Delakrua and, jointly with the latter, obtained a privilege in Russia for an apparatus of this system (with the introduction of certain constructive modifications). This device, under the name of the sterilization-utilization apparatus of the Delakrua–Voevodskii system, was successfully applied at the Petersburg municipal slaughterhouse. An interesting feature of this device is that the apparatus is supplied with steam from a steam boiler heated by a regenerative furnace for burning refuse, of a special system developed by V. G. Voevodskii *).

*) A description of this furnace was received only after the printing of the part of our work relating to the destruction of refuse, and therefore we include it in the present chapter.

The apparatus of the Deliakrua–Voevodsky system, installed (initially) at the St. Petersburg municipal slaughterhouse, is shown in drawing 15a together with a transverse section of the furnace through the boiler, firebox, and generators. It is not difficult to see that its construction differs from the apparatus of Deliakrua described above only in details, and therefore is entirely clear from the drawing. The dimensions of the apparatus may vary, depending on need and on the method of charging, whether with whole carcasses or with parts of them. V. G. Voevodsky considers the most practical dimensions of the apparatus to be those corresponding to drawing 15a, where the main cylinder has a diameter of 1100 mm and a height of 2000 mm. With this size it is possible to charge from 75 to 125 poods at one time. The installation of such an apparatus, with a special boiler for it, cost 6000 rubles.

A peculiarity of working with this apparatus is that in it the solid residue is also dried, by admitting steam into the steam jacket of the apparatus. It must be supposed, however, that in the absence of devices for mixing, such drying is hardly sufficiently uniform and complete. This is also indicated by Mr. Voevodsky’s remark in his description of the operation of the apparatus, concerning the need sometimes to dry the product further in special devices.*)

The steam required for the operation of the Deliakrua–Voevodsky apparatus, as indicated above, is supplied by a steam boiler heated by a regenerative furnace of Mr. Voevodsky’s system for the destruction of waste. This furnace, according to the inventor’s idea, is intended for the complete combustion, without smoke, of various wastes—namely intestinal contents, sewage sludge, manure, refuse, and other thick and solid impurities from slaughterhouses that are subject to destruction—with utilization of the heat from this combustion for heating the boiler. This furnace consists of the following parts (drawings 15b and a):

1) generators (also destructors) $aa$, one or several, depending on need, in the present case two;

2) the main firebox $B$, where the final combustion of the gases takes place, connected with the steam boiler $P$;

3) the regenerative chamber $C$;

4) the drying chamber $D$;

5) the steam boiler $P$;

6) the smoke stack $E$.

) “The dried mass is unloaded from the boiler through a hatch arranged at the bottom above the false bottom and, if it proves necessary, it is placed for some time in any dryer, where it quickly dries completely; it is then ground…” (V. G. Voevodsky. The Arrangement of Rational Slaughterhouses*, etc., p. 27).

These parts may be arranged in another order and at another height, depending on local conditions and on the materials that are to be burned.

The generator consists of two main parts: the upper cylindrical part, the so-called preheater \(a\), and the lower part—the generator-destructor proper \(A\) (cf. drawing 15a). The material intended for incineration enters through the preheater \(a\), whose cast-iron casing is surrounded by channels \(a_1\), conducting part of the combustion products from the main furnace \(B\). The channels \(a_1\) are arranged in such a way that the combustion products enter from below, while their outlet into the channel leading to the chimney is located above. Thus they move in a direction opposite to the movement of the material being charged, whereby better utilization of heat is achieved.

The lower part of the generator, i.e. its furnace, has two doors, of which one, the lower one, in the ashpit, serves for the admission of air and is therefore provided with a special device for regulating its inflow, while the second, upper one, is for observation and for poking during operation of the furnace. The admission of air into the generator is best carried out by artificial draft—with the aid of a fan—in cases of more energetic combustion of the material.

The combustible gases formed in the furnace of the generator pass through the opening \(a_4\), along the channel \(a_5\), into the collector \(a_6\), and from there into the main furnace \(B\), through the channel \(a_7\), located above the throats \(b_1\). The channels \(a_5\) are provided with special dampers for regulating the inflow of gases into the furnace \(B\).

The main furnace \(B\) consists of two principal parts: the front part \(b_0\), which is provided with grate bars and two hermetically closing doors, one into the ashpit and the other into the furnace itself, and serves for heating the furnace at the beginning of its operation; and the rear part \(B\), where the final combustion of the combustible gases of the generator takes place after their mixing with the hot air of the regenerator. For this purpose, in the floor of part \(B\) of the furnace, above the two channels \(a_7\) and \(c_6\), there is arranged a row of throats \(b_1\), through which gas enters from the channel \(a_7\), and hot air from the channel \(c_6\).

The furnace \(B\) has three outlets. Of these, the main one, \(b_2\), through which the combustion products pass under the steam boiler \(P\), whence they then proceed first through the channel \(p_1\) into the regenerative chamber, then into the drying chamber, and finally into the chimney. The second small outlet \(b_3\) serves for conducting part of the combustion products from the main furnace \(B\) through the channels \(b_4\) into the channels \(a_1\) of the preheaters \(a\), whence they pass along the channel \(b_6\) directly into the chimney. The third outlet \(b_5\) serves for the passage of the combustion products past the steam boiler,

The steam boiler \(P\) in the present case is tubular, but it may also be of another construction. The steam formed in it is conducted into the sterilizing apparatus through the steam pipe \(t_1\).

The regenerative chamber \(C\) serves to heat the air intended for the combustion of gases in the main furnace. At the bottom it consists of two rows of cast-iron pipes \(c_1\), into which air enters, and in the upper part of channels \(c_2\), surrounded by flues \(c\). The products of combustion from the main furnace pass through this chamber in three turns, enclosing the channels \(c_2\) and the pipes \(c_1\), and thereby heat the air intended to support combustion. This air enters the regenerator from the drying chamber \(D\) from below and, rising upward through the pipes \(c_1\) and the channels \(c_2\) in five turns, collects in the upper part of the regenerator in the channel \(c_3\), from which, through the channel \(c_4\), it passes over the crown of the furnace \(B\) and finally enters through the channels \(c_5\) and \(c_6\) into the neck \(b_1\) for mixing with the gases. To regulate the inflow of air into the channel \(c_3\) there is a special damper. At the bottom of the third turn of the regenerative chamber there is placed a large cast-iron pipe \(c_8\), through which the outside air passes into the drying chamber, being heated incidentally.

The drying chamber \(D\) serves for the preliminary drying of the materials intended for incineration, by means of the heat of the products of combustion already going out into the chimney, whereby a very complete utilization of all the heat released is achieved. This chamber has, as is seen from the drawing, three tiers, separated from one another by iron longitudinal channels \(d_1\), through which the products of combustion pass until they exit into the pipe, thus heating both the walls of these flues \(d_1\), the upper part of which forms the floors of the separate tiers of the drying chamber, and the entire chamber. For the ventilation of this chamber, heated air is admitted, as stated above, through the pipe \(c_8\), and the openings for the air outlet are connected with the pipes of the regenerative chamber. To intensify the ventilation of the drying chamber, part of the exhaust pipes may be introduced into the ash pit of the generator. In this way the direct escape of the products of evaporation into the atmosphere is eliminated. For loading, unloading, and moving the material, the drying chamber has doors \(d_4\), located in all tiers of the chamber; in the present case, three in each tier. The drying chamber is loaded from above, i.e., the materials first enter the upper third tier, then, gradually being moved, enter the middle tier and finally the lower tier, whence they are then directed into the generator.

In the present case the generators are shown separately from the drying chamber. To avoid overloading with half-dry products, the generators should be arranged directly beneath the drying chamber.

The flue pipe \(E\) at the bottom is divided into two parts, of which one, \(e_1\), is for the exit of the products of combustion that have passed through the dryer; the second, smaller one, \(e_2\), is for the products of combustion passing through the channel \(b_6\).

The operation of the furnace described is clear from the foregoing and consists, in general, of the following. After the drying chamber has been loaded with the raw material intended for incineration, the furnace is started by means of the front part \(b_1\) of the main firebox \(B\). Then the generators are put into operation, and when energetic combustion of the gases begins in the firebox \(B\), the furnace is in full operation, and the products of combustion may be admitted for heating the steam boiler \(P\). Upon the steam boiler’s reaching the required pressure, it can be supplied through the steam line \(t_1\) to feed the sterilization apparatus.

A necessary component of establishments for processing meat refuse by means of disinfecting-type apparatus is equipment for drying and grinding the solid residues of the treatment. It is therefore necessary to say a few words about this equipment.

For drying solid residues, use is made (if one does not speak of air drying, which is not employed in well-equipped establishments) of special so-called drying apparatuses, constructed by various firms. Of these, the better-known are the apparatuses of the Otto, Rübenkamp, Bittner and Meyer, and Rietschel and Henneberg systems.

The drying apparatus of the Otto system was introduced in 1892 by the firm F. G. Otto in Dortmund. The apparatus consists (Fig. 16) chiefly of two or a larger number of trough-shaped vessels with double walls, arranged one above another, in which the product being dried is constantly mixed by paddles. The troughs themselves are heated by steam. In the lower trough, in addition to the agitators, there also moves a tubular coil, likewise heated by steam, whose purpose is, by increasing the heating surface, to accelerate the drying process. Often, however, if the incoming material, as in the present case, is not so sticky as to envelop the heating coil and paralyze its action, such a coil is also fitted in the upper trough, and then the construction of the upper and lower parts is identical. The number of revolutions of the agitators is made 15–20 in the lower trough; in the upper one it is brought up to 40–50, in order to prevent particles from adhering to the walls and agitators.

The steam jacket of the trough-shaped reservoirs is divided by a special wall into two parts in such a way that the steam first penetrates into one half, and then passes from the opposite end into the other. The apparatus is heated in such a manner that the steam is first conducted into the upper reservoir, into which the material to be dried enters. After the steam has passed around half of the steam jacket of the upper trough, it is led into the lower one, where it follows the same path. Finally it enters the tubular spiral, where it remains until condensation, after which it is discharged by a special pipeline, through a condensation pot, into the sewer.

Very often, exhaust steam from working machines is used for drying, thereby producing a considerable economy. The use of exhaust steam is even preferable in cases where, owing to the nature of the material, the use of a high temperature is undesirable. Such a case occurs in the application to the dry residues from the processing of meat material, if the product from them is to be a feeding fat.

Otto’s apparatus is tightly closed on all sides and, in addition, is provided with wooden sheathing in order to reduce heat losses from radiation. The water vapors and gases formed in the apparatus are carried off by a pipe, which is connected to the upper part of the cover of the apparatus. This pipe, as experience has shown, must be up to 10 meters high and, in order to avoid back-condensation of water, must be surrounded by a poor conductor of heat.

The introduction into the apparatus of the material subject to drying is carried out through a funnel entering the upper reservoir and connected with an Archimedean screw, which advances the loaded material at a definite speed. This device also serves to move the material within the apparatus itself, forcing, by means of the uniform supply of fresh material, the semi-dry product inside to move forward. In this way the material subject to drying gradually passes through the upper trough, falls into the lower one, and here, little by little, as it dries, moves toward the discharge opening.

The following indisputable advantages must be recognized for the apparatus of the Otto system:

1) the development, within a comparatively small space, of a considerable heating surface;

2) the complete utilization of the steam serving for heating, up to condensation;

3) the possibility of regulating the temperature by means of special devices;

4) cleanliness of operation, owing to the hermetic closing of the apparatus;

5) the very simple construction and servicing of the apparatus.

The drying apparatus of the Rubenkamp system consists of a drying chamber and a compartmented trolley supplied with sections, which is loaded with the material to be dried and is pushed into the chamber. The meat parts may either be hung on hooks in the compartments of the trolley, or placed on perforated iron trays, beneath which there are cups for collecting fat; the latter flows from them into a collecting chamber under the trolley and from there is subsequently drained off. Drying is carried out by hot air, which is brought into the chamber through numerous pipes and channels and, having completed its circulation in the chamber, exits into the chimney. The gases and vapors released during the drying of the material are drawn into the furnace and are burned there.

Besides these apparatuses, the drying apparatus of the Bittner and Meyer system, which appeared considerably earlier, is also widely used. Not yet having a description of this apparatus, I nevertheless consider it necessary to mention it, precisely in view of its fairly frequent application.

For crushing and grinding the dried meat material, with the aim of converting it into the final product—animal tuch—crushers and mills of various systems and firms are used, bearing the names of crushers, disintegrators (for example, those of Nagel and Kemna), mills (Excelsiormühle, for example, of the Grusonwerk factory in Magdeburg-Buckau), and so on.

The firm Rietschel and Henneberg, in constructing its cafil-disinfector, likewise had to take into account the inconveniences arising from moving the semi-finished material for drying. Taking these inconveniences into consideration, it constructed a special apparatus for drying the solid residues from processing in the disinfector, bearing the name of the firm. For receiving the material being dried there serves vessel $A$ (Figs. 17 and 18), with a corresponding device for filling, having at the bottom a grate $B$, onto which the material subject to drying falls. Under vessel $A$ there is a second vessel $C$, with two cylindrical chambers, in which stirrers $D$ move. The sharp fingers of the stirrers pass through the spaces between the bars of grate $B$. The adjoining walls of the cylindrical chambers are provided at $E$ with openings, which allow the ground and dried material to pass into channel $F$, equipped with an Archimedean screw.

The lower part of the apparatus consists of the chamber \(K\), in which the firebox \(H\) is located. The gases produced by combustion are conducted through the pipe \(J\), which passes in several bends inside the cavity \(K\) and in this way heats the air contained in it. The hot air first heats the cylindrical chambers \(C\) from the outside, then enters them from above and from the sides, and finally penetrates through the grate \(B\) into the vessel \(A\), from which it is already drawn by the fan \(M\) into the pipe.

How convenient the apparatus described has proved to be in practice is, unfortunately, not yet known. The transfer of the material intended for drying from the disinfector to the drying apparatus is carried out in the following manner. The inner cylinder of perforated iron shown in drawing 14 is removed with all the contents in it from the sterilizer \(A\) by means of a light movable crane and, being moved, is placed over the receiving opening of the drying apparatus. Here the slide is opened, the bottom of the cylinder, consisting of two halves, opens, and the material falls into the opening of the drying apparatus.

It cannot be said, of course, that this method of transferring boiled animal material is irreproachable. But in any case it offers considerable advantages in comparison with carrying by hand. This circumstance, together with the merits of the drying apparatus of the Rietschel and Henneberg system, in comparison with ordinary dryers and drying cabinets, compels one to regard the construction created by the firm as a substantial step forward.

In order to get rid of that substantial inconvenience in the operation of a kafill-disinfector which is presented by the transfer of semifinished products from one apparatus to another, the firm Rietschel and Henneberg set itself the task of constructing a disinfector combined with a drying device. This idea was realized in the new device shown in drawing 19.

At one quarter of the total height of the sterilizer \(A\) there is arranged a shaft \(W\), on which are mounted spokes \(a\) with lateral teeth \(s\). Between these movable spokes \(a\) pass fixed horizontal bars \(a\), of the same construction and with the same teeth. These latter, when the spokes \(a\) are in the horizontal position, form a circular grate, in which the teeth \(s\) of the movable spokes are placed between the teeth of the fixed bars in such a way that the raw material being processed is very conveniently arranged on them. Beneath this grate there is a grated bottom \(K\), having the form of a hemisph—

... it. The rim surrounding it above is attached, by means of a hinge and latches, to a ring which is rigidly connected with sterilizer \(A\).

During the evaporation process, the liquid released from the material resting on the aforementioned temporary grate drains off, passes through the openings of the grate, and then through the apertures of the perforated hemispherical bottom, and collects at the bottom of the sterilizer. From there it is led away, in the already known manner, into a receiver by means of pipe \(r\) and valve \(v\).

After evaporation has been completed, steam is admitted into the steam jacket of the apparatus in order to dry the cooked bone and meat masses, and at the same time shaft \(W\) is set in rotary motion. The teeth described above, partly fixed and partly movable, then act in a crushing manner; and when the material, in the form of small pieces, reaches the hemispherical bottom \(K_1\), the movable spokes \(a\) act upon it like stirrers. For the vapors and gases released during the drying process, an appropriate draft must, of course, be provided in the upper part of the disinfector. The dried and comminuted mass is removed from the apparatus through a special opening, after the bottom \(K_1\) has been taken off.

There were as yet no reports concerning the practical suitability of the device just described. In any case, from the technical point of view, the apparatus is satisfactory for its purpose and very ingenious. It is of interest also because it represents a transitional type from disinfectors to the so-called universal utilization apparatuses.

Two varieties of apparatus for the treatment of meat refuse also belong to the disinfectors; they were designed by Rudolf Hartmann and called by him extraction apparatuses (Hartmanns Extractions-Apparat).

The Hartmann extraction apparatus in its original form consists (Fig. 20) of three vessels communicating with one another: a vertical cylinder \(a\), serving for cooking the raw material; a horizontal cylinder \(b\), for evaporating and thickening the glue liquid; and finally a condenser \(c\), in which the vapors released during operation are condensed.

As is evident from the drawing, vessel \(a\) is hermetically closed above by a strong lid, and at the very bottom it has tubes for steam heating in the form of a coil, communicating with the steam boiler by means of valve \(d\). The water condensed in these tubes is removed by means of a special conduit \(g\) and can again be used to feed the boiler. The evaporating apparatus \(b\) is provided with a steam jacket \(e\), connected—

connected to a steam boiler by means of the steam valve f. Both vessels a and b communicate with each other by a pipe running from the lowest points of both; this pipe is closed by the valve h. In addition, from both vessels, beginning at their upper points, two pipes with valves k and l run and then join into one common pipe, the continuation of which is the coil of the condenser. Finally, from the highest point of vessel b a pipe runs into vessel a, entering the latter beneath the perforated bottom and capable of being closed by the valve i. Under the bottom of the condenser there is arranged a glass vessel, allowing one to see the water flowing from the coil. This pipe then leads into the sewer. Gases that cannot be condensed in the coil are carried, by means of a gas pipe attached to the glass vessel, into the furnace of the boiler and are burned there.

The procedure of production in Hartmann’s extraction apparatus is as follows. Vessel a is charged with the raw material, which is placed on the perforated bottom and is separated from the outer walls of the vessel by an inner perforated cylinder. A little water is then admitted into the apparatus and, opening the steam valve d, steaming is begun. The admitted steam envelops and heats the raw material, as a result of which the water contained in the latter is released. Mixed with gluey substances, it flows downward and there is partly converted into steam by the steam coil lying on the bottom (which is indicated in the transverse section). When such an amount of water has been released that its level is visible in the water-gauge glass arranged on the wall of cylinder a, valves h and i are opened; the gluey liquid then flows through valve h into vessel b, until its levels in both vessels become equal. Of course, in this way only the glue water should be allowed to run off, while the fat released from the raw material remains in vessel a. After this, valve d is closed and, by opening valve f, the steam jacket e is heated. The gluey liquid in b is thereby brought to boiling, and the steam that is released passes through valve i into vessel a. At the same time, from a into b there flows the glue water abundantly released under the action of the steam, while the fat extracted simultaneously from the fleshy parts accumulates in vessel a. Since the boiling of the water takes place exclusively in vessel b, whereas in a it remains in complete rest, the fat is readily clarified, while the heavier dirty particles by specific gravity it gives up to the gluey liquid lying beneath it. In a relatively short interval of time the fat becomes …

so pure that it can be discharged during production through a tap arranged at the side. In this way the system of apparatus is filled with steam released exclusively from the water of the raw material, the temperature and pressure of which are approximately the same as those of the boiler steam entering through the valves \(f\) and \(d\). Under the action of this steam, the evaporation process is successfully brought to completion.

When this process may be considered to be approaching its end, the concentration of the glue liquor is begun. For this, the valves \(l\) and \(i\) are opened slightly, so that part of the vapors released in \(b\) gradually passes into the condenser \(c\) and is condensed there. At the same time the glue liquor located in \(b\) gradually becomes more concentrated, until finally, at the end of the whole process, it reaches the desired syrup-like consistency. It is then discharged through a tap or drawn off for further processing into glue.

By the process described above, the charged material is separated into three constituent parts, namely glue gelatin, fat, and evaporated meaty mass. Only those elements remain unused which are carried away by the steam and, after passing through the condenser, are discharged into the sewer.

The filling of vessel \(a\) is carried out with the aid of a cylindrical basket inserted into it from above, with perforated walls and bottom, into which all the raw material is placed. After being introduced into the apparatus, this basket replaces the inner perforated cylinder. Upon completion of the processing, the basket has to be pulled out in order to transfer its contents to the drying apparatus.

In order to facilitate the task of charging and emptying vessel \(a\), the firm Rud. Hartmann later modified the construction of the extraction apparatus. Vessel \(a\) was arranged horizontally, which made it possible to charge the raw material by means of a perforated basket moving on wheels, in which, after the evaporation process was completed, it was again rolled out. The new arrangement provided free access to both bases of the cylinder, whereby the insertion of the filled basket and the emptying of the apparatus could be carried out from two opposite sides. In this way the advantage is obtained that the room in which the raw material is kept can be completely separated from the apparatus room intended for processing, and this is very desirable in the interests of hygiene.

Fig. 21 shows just such a horizontal Hartmann extraction apparatus. This latter, like that shown in Fig. 20, consists of three separate vessels, of

...of which each has the same purpose and which communicate with one another in the same way. Thus, steaming takes place in the horizontal cylinder \(a\), evaporation of the glue liquor in cylinder \(b\), and thickening of the vapors in condenser \(c\). Valves \(i\) and \(k\) serve to conduct the vapors to the condenser; valves \(g\) and \(h\) admit steam from the boiler respectively into the steam jackets \(e\) and \(f\); and valves \(l\) and \(m\) serve to connect vessels \(a\) and \(b\) with each other.

In this apparatus the outflow of the condensed liquid likewise takes place through the glass vessel \(p\). This latter device is very practical, since, by observing the quality and quantity of the liquid flowing off, one can monitor the correctness of the process. Under a normal process there should flow off a liquid as clear as water. If its color is milky, this is a sign that, owing to some oversight, fat has been distilled from vessel \(a\) into \(p\). A dark coloration of the liquid indicates that the steam valve \(k\) is opened too much, and that as a result the glue liquor is being carried along with the steam into the condenser.

The devices just described, known under the general name of disinfectors or extraction apparatuses, represent an undeniable step forward in comparison with simple evaporators or digesters in the sense of completeness, thoughtfulness, and practicality of construction. Greater perfection in the apparatus has entailed a noticeable success with respect to the quality and cost of processing, and has made possible a considerable development of production equipped with these apparatuses. It has also ensured a significantly greater cleanliness and hygienic character of the processing operations.

However, apparatuses of this type are not free from serious shortcomings. Despite a rather noticeable complexity, they still leave much to be desired both with respect to the perfection of the processing, and especially with respect to its cost. But most important—there remains with them a serious deficiency in hygienic terms, inevitably arising from the nature of their operation. The point is that the process of treating animal material does not end in that group of devices which constitute the disinfector. The work is divided between them and other devices—for drying and comminution. The disinfector gives only semi-products and, most importantly, these semi-products must be removed and transferred for subsequent operations, which, owing to the peculiarities of the material, proves extremely unpleasant and undesirable.

After this it is understandable that technical thought could not rest content with apparatuses of the type described above and, striving toward improvement—

...processing them in different parts, set as one of the chief tasks—to combine in one apparatus, or a connected group of them, as far as possible, all the processing operations. Work in this direction led to the creation of apparatuses which, unlike all those described above, processing the material in a partial manner, perform all processing operations (with the exception of final grinding) without removing the material from them, and therefore bear the name of universal utilization apparatuses.

XI. Sterilization and processing of confiscated materials and animal carcasses in universal utilization apparatuses.

All devices known under the name of universal utilization apparatuses, while differing in the details of their construction, are similar in their basic idea. The essence consists in the fact that the carcass material is processed in one uninterruptedly connected and hermetically closed system of apparatuses from beginning to end, without removing it from the apparatuses until the final product is obtained in a completely finished, or at least completely unobjectionable, form in the sense of handling it. Here it is first boiled down in the sterilizer under high pressure, rapidly and completely separating out pure fat, which is discharged into collecting vessels. Then the remaining gluey broth passes into an evaporating apparatus of the system for concentration. In some systems it is first collected in a special closed reservoir, where it remains until the next operation and again serves to fill the apparatus in place of water, and is sent for processing into glue only when it has become sufficiently saturated with gluey substances. Quite often, however, the processing of the gluey liquid is omitted. The solid residue remaining inside the sterilization apparatus is dried in the same apparatus under the influence of high temperature. Then, since, owing to the high temperature of processing, it comes into a very friable state, in this same apparatus it is easily crushed by simple devices, turning into a more or less fine dry powder. Thus all the essential operations are carried out in one and the same system, chiefly in the sterilizer, which is why these devices do indeed deserve their name of universal. Only one operation goes beyond the limits of the system—this is the regrinding of the finished cake into finer particles, which is performed on special mills.

The first, in order of appearance, among the universal utilization apparatuses is the apparatus of the Podewils system.

This apparatus, in the form in which it is used at the present time, was developed gradually, by a path of successive improvement, at the utilization plant in the city of Augsburg, not far from Munich in Bavaria, belonging to a joint-stock company and processing (for more than 20 years) all the slaughterhouse refuse of the local abattoir and knackery. It received its name from the founder of the enterprise, Baron A. von Podewils. The very type of this apparatus was developed on the basis of many years of experiments by the same company at its large bone plant in Graz, where up to 100,000 centners of bones are processed annually for the production of fat, glue, and bone meal.

The utilization apparatuses of the Podewils system used in practice, of various sizes, reduce to three types: the ordinary utilization apparatus, the utilization apparatus with a large manhole, and the so-called tilting drum of the Podewils system. The action of all these apparatuses is the same; as regards construction, however, there is some difference.

The chief component part of the ordinary Podewils utilization apparatus (Figs. 22–24) is a strong iron drum of cylindrical form, with double walls, provided also with double bottoms, the walls of which present two surfaces convex in different directions. The spaces between the double walls of the drum and between the double walls of the bottoms constitute the steam jacket of the apparatus. For the purpose of constant communication, when being filled with steam, the separate parts of the jacket are connected with one another by small steam pipes (D, Fig. 22). In addition, for the discharge of condensation water from the jacket, in its lower part there is an opening connected with pipe C. The drum is hermetically closed by cover M (Fig. 23) with gaskets of rubber or of another impermeable material. This cover serves for loading the drum with cadaveric material and for emptying it of the dry products of treatment. In cover M an opening F is made, connected with a short pipe, hermetically closed by means of a cock. This pipe is periodically connected, by screwing, with pipe F and serves for the discharge of the separated fat.

Two hollow trunnions are attached to the bottoms of the drum on both sides, by means of which the drum can rotate freely in bearings arranged on beams or supports. This motion is produced by means of a gear transmission, consisting of a large toothed wheel encircling on one side the cylindrical surface of the drum and meshing with a pinion—

Ya. I. Nikolin.

a gear wheel, which is mounted on a shaft transmitting motion from the machine. The trunnions of the drum are made hollow because, besides supporting the drum, they must at the same time serve for admitting an entire series of pipelines into it. For this purpose they are provided at their ends with stuffing boxes.

The pipelines passing into the drum are as follows. On one side, through the trunnion of the apparatus, provided with a stuffing box, there enters tube \(D\) (Fig. 22), which conducts fresh steam from the boiler first into one of the double bottoms, and through it also into the entire steam jacket of the drum. By means of a special branch, not shown in the drawing, steam may also be admitted into the apparatus. Through tube \(D\), in turn, passes tube \(C\), connected with opening \(f\) and carrying off the condensation water from the steam jacket, which is used for the most part again to feed the steam boiler. Both tubes are provided with cocks.

On the other side, through a similar trunnion provided with a hermetically closing stuffing box, passes the bent pipe \(a\), with openings at its free end in the form of a sieve. It can be turned and moved from the upper position to the lower one by means of the hand lever \(h\), located outside the apparatus. With its outer end it enters, likewise by means of a stuffing box, into the hollow spherical box \(V\), furnished with a mesh, which can connect it, by turning the appropriate cocks, with three pipelines: with the water pipeline leading to the pressure vessel, with a special branch of the steam line leading to the steam boiler \((d)\), and with the gas pipeline leading to the air pump and condenser \((e)\). By means of this connection one and the same pipe serves for filling the apparatus with water from the pressure vessel, for discharging water back into that vessel, for admitting fresh steam into the apparatus, for pumping air out of the apparatus at the beginning of the operation, and for discharging vapors into the condenser during drying. Each of the pipelines listed is provided with a hermetically closing cock. In addition, the water pipeline leading from the pressure vessel \((z,\) Fig. 23) has a further connection with the interior of the drum, through its lower part, by means of an opening and a branch provided with a cock.

Inside the drum there is placed a heavy, hollow, freely moving shaft, serving to crush the dried solid residues of the treatment. The drum is made of carefully welded, thick sheet iron; the trunnions are of steel. The gear wheel for setting the drum in motion is screwed to one of the bottoms, in order to ease the work of the trunnions. The entire outer side of the drum.

is protected against heat loss by the admission of steam, with the aid of a casing made of non-heat-conducting material.

A necessary addition to the Podewils system apparatus is the so-called pressure reservoir, a condenser, and a pipeline carrying off the fat, with a device for cooling and thickening the latter.

The pressure reservoir ($F$, drawing 24) serves for storing the glue broth remaining after the boiling of the raw material and for heating it to a definite temperature (up to 160°) and at a definite pressure (3 atmospheres), before it is admitted into the apparatus. This glue broth is used for filling the apparatus in several operations; each time, becoming more and more saturated with glue substances, it is discharged into the sewer (the Podewils firm in principle refrains from further processing it into glue), only when it has become excessively saturated. In the former design, recently abandoned by the firm, instead of this apparatus a fat separator was used, into which all the liquid products of steaming were discharged. The pressure reservoir itself is a large iron cylindrical vessel, with convex bottoms, standing on a special foundation. It is riveted from the same material as the sterilizer drum. It is connected, by means of pipelines, with the following elements of the equipment of the utilization plant: 1) with the steam boiler, for obtaining fresh steam, the steam being able to enter it through three branches of the steam line: from below, at mid-height, and from above, depending on whether the liquid is to be heated or only the pressure established; 2) with an air pump for reducing, when necessary, the pressure in the vessel; 3) with the interior of the rotating drum, by two routes, as was indicated above.

The condenser ($C$, drawing 24), the arrangement of which varies, plays the same role as in the apparatuses described above.

The pipeline for the fat consists of the following parts:

1) the pipeline itself, on one side periodically connected by means of a screw coupling to pipe $F$ (drawing 24) with a cock, and on the other passing through refrigerator $K$ and gas separator $G$ and leading the fat obtained through pipe $R$ into a collecting vessel;

2) refrigerator $K$ for cooling the melted fat, especially in the final moments of discharge;

3) gas separator $G$, from which the gases pass under the grate of the steam boiler, and the fat into the further part of the pipeline.

The arrangement of these parts is clear from the drawing.

Where large loads have to be processed (120–150 poods), in which there are, moreover, whole carcasses of large animals, the so-called large Podewils apparatus is recommended, 3500 mm long, with a large manhole of special design, measuring 1200 × 1000 mm, automatically and tightly closed by an inner cover. The construction of such an apparatus is exactly the same as that of the ordinary Podewils apparatus. Only its covers are made more solidly, in accordance with the larger dimensions.

The tipping drum of the Podewils system (Fig. 25, in the plan) permits whole carcasses to be treated in an apparatus of ordinary size. For placing whole carcasses inside, the drum has a removable cover \(D\) and, on the sides, two bushings for temporary trunnions forming its transverse axis, so that it can be set upright, with cover \(D\) upward, or overturned; for this reason it has received the name of a tipping drum. The remaining parts of its construction and its operation are exactly the same as in the ordinary Podewils apparatus. The tipping drum also has a manhole \(m\) for filling it with ordinary carcass material.

In those cases where it is required to place a fallen animal whole into the apparatus, the procedure is as follows. Having disconnected the pipelines on both sides, temporary transverse trunnions are inserted by hand. Then the bearing covers \(L\) are released. The temporary trunnions indicated rest on their bearings and take upon themselves the whole apparatus. After this the drum becomes able to rotate about its new transverse axis and is overturned into a vertical position, with cover \(D\) upward. The cover is removed, and the whole carcass is placed inside, with the aid of a winch. Then the cover is screwed on again, the drum is turned back into its original horizontal position, the trunnions are removed, and the pipelines are again screwed together with couplings. The carcass remains in the apparatus until its treatment is completely finished.

Thus the tipping drum of the Podewils system very successfully solves the problem of destroying whole carcasses of large animals in one and the same apparatus. The entire process of treatment—steaming, sterilization, extraction of fat, drying, and comminution—takes place in one and the same apparatus, the interior of which is completely cut off from the outside air throughout the entire working process, up to the formation of a completely dry powder, which, after the completion of treatment, is discharged through the manhole \(m\). The use of the Podewils tipping drum is recommended where what is chiefly contemplated is the treatment of whole carcasses, not

bringing it to division into parts. Tilting drums are built with a capacity for a charge of about 60 poods.

Podewils’ firm manufactures apparatuses of its system in the following sizes and capacities:

No. of apparatus	Practical output in 10–12 hours of work, kg	Approx. output, centners per day of work, kg	Required heating surface of the steam boiler, sq. m	Required mechanical power, hp	Required floor space, sq. m	Dimensions of the interior of the cylindrical drum: internal diameter, mm	Dimensions of the interior of the cylindrical drum: length, mm
I	400	700	6	1	10	1000	1000
II	600	1000	9	1	12	1000	1500
III	1000	1800	15	1–2	15	1000	2500
IV	1500	2500	20	2	20	1500	2500
V	2000	3500	25	2	25	1500	3500
Tilting drum	1000	1800	15	1–2	20	1200	2000

The apparatus comprises: a pressure reservoir (the glue apparatus) or (in the earlier design) a fat separator, a condenser, a cooler for fat, a gas separator, a receiver for fat, a frame, a transmission mechanism, and pipelines.

Turning to the description of the operation of Podewils’ apparatuses, we must bear in mind that the operation of apparatuses of all three types is entirely the same; consequently, it is sufficient to describe the operations with one of them, for example, with the ordinary Podewils apparatus, in order to know the operation of the others. Here we shall briefly describe production in the Podewils apparatus of the earlier design (with a fat separator), so as not to repeat ourselves later, when we shall have to set out the same thing in detail with respect to the new design in describing the Odessa utilization plant. The operation of the apparatus proceeds as follows.

As soon as the drum has been filled through the opening with parts of carcasses and other material, and the opening has again been hermetically closed, first of all the air is removed from the drum by means of an air pump; a certain quantity of water (or glue liquor) is admitted, and then the boiling process is begun. The steam admitted into the drum condenses on parts of the meat carcasses and gradually heats the latter to 160 degrees. At this point the charged material decomposes, fat and glue substances are separated out, and after several hours the contents of the apparatus constitute, in themselves,

a semiliquid mass. After this, the drum is made to rotate quietly for a certain time (until then it had been at rest). In this, the separate solid parts are crushed by the freely rotating roller; in the overall mass a moderate movement sets in, which promotes the separation of the fat. Following this, the apparatus is again stopped for a prolonged time, so that the mass, homogeneous until then, may separate, according to the specific gravities of the component parts, into several layers: fat, glue water, meat and other fibers, and bone residues.

When such separation has been achieved (for which night hours are usually used), the connecting pipe leading to the fat separator is opened, the pipe \(a\) (Fig. 22) is turned by means of the lever \(h\) until it enters the layer of fat, and the latter is driven by the pressure in the drum into the fat separator. Since the separate layers in the sterilizer are not visible from outside to the operators, one must be careful and, in order to extract as much of the fat as possible, it is necessary also to transfer part of the glue liquid into the fat separator. A pipe, of length less than the diameter of the cylinder, enters the fat separator somewhat above its lower base; this pipe is rotated from outside by means of a hand lever and can be brought into a vertical and a horizontal position. By means of this pipe the fat is removed from the fat separator, after it has been separated from the glue liquid. The remaining liquid is subsequently transferred back into the drum at a new charge.

Meanwhile, after the liquid products have been discharged, the drum is set in rotary motion and the steam jacket of the apparatus is heated in order to dry the remaining material.

The vapors formed during drying are led through pipe \(a\) into condenser \(C\), where absorption of vapors and gases takes place. The water from this condenser, after being mixed with 10–20 parts of clean water, is then discharged into the sewer or into the rapid current of a river. Where the composition of the subsoil permits, after dilution the water is led directly into the ground. If there is not enough water for dilution, the condensation water is collected undiluted in reservoirs or pits, freed from its bad odor by chemical admixtures, and removed from there from time to time. The gases not condensed during condensation are either led away for combustion under the boiler furnace, or discharged through a high pipe.

The drying of the material continues while the drum is rotating until the entire material is crushed by the freely rotating roller located in the drum and turns into a dry powdery mass. By samples, which can be obtained through a specially arranged opening in the drum, the time for

...emptying of the apparatus. Removal of the finished product is carried out by opening the aperture in the drum and overturning the latter. The dried product contains still larger lumps, from which it is separated by sifting. These coarser parts are ground in a mill or are processed again when the apparatus is newly charged. The powder sifted through the sieve is the product ready for sale.

The processing of one charge (or batch, as specialists in the matter put it) requires 20–22 hours, of which 3 hours are spent on steaming the material, from 6 to 9 hours on separating the products, and from 11 to 12 hours on drying the solid substances.

Utilization plants equipped with Podewils-system apparatuses are found abroad in the cities of Augsburg (Bavaria), Brünn (Austria), Vienna, Hamburg, Groningen (Holland), Dresden, Kapstadt, Lausanne, Mainz, Munich, Oldenburg, Olmütz (Austria), Odense (Denmark), Poznań, Zurich, and a number of other cities. In Russia, utilization plants with the same apparatuses exist in Kiev, Moscow, Odessa, Riga, and Yuryev (Dorpat). Among the illustrations appended to the present article there are, in addition to drawings of the Odessa utilization plant, an interior view of the room for apparatuses at the utilization plant in the city of Dresden (Fig. 25a) and plans of the room for utilization apparatuses at the municipal slaughterhouse in the city of Yuryev (drawings 26–28). Here the individual elements of the equipment are denoted by the following letters:

A—Podewils apparatus;
B—pressure reservoir;
G—condenser;
D—gas separator;
E—reservoir for water;
S—cooler for fat;
F—barrel for fat.

The firm Rud. Hartmann, whose extraction apparatuses were described above, while making efforts to eliminate the defects inherent in apparatuses of this kind, in its turn approached the solution of the problem by inventing a universal utilization apparatus of another system, bearing the firm’s name. In the Hartmann-system utilization apparatus (drawing 29) the raw material is received into a horizontal drum with perforated walls a, situated inside another horizontal iron cylinder with double walls b. The inner drum can be set into rotary motion about an axis passing through the outer cylinder and terminating in a pulley, and is heated by steam both directly,

both by means of the steam jacket surrounding it, cylinder \(b\). The interior of the apparatus is connected by pipeline \(c\), closed by a valve, with a second vessel, \(e\), which in turn communicates with the evaporating apparatus \(g\) by means of pipe \(f\). The evaporator \(g\) is provided inside with a steam coil \(h\) and communicates with the first vessel, the sterilizer, by means of pipe \(i\). This latter, through valve \(l\), leads into the steam jacket \(b\) and, in addition, through valve \(k\), into the interior of the apparatus. Pipeline \(m\) conducts steam from the boiler into the steam jacket.

The processing is carried out in the following order. First of all, the inner perforated drum is filled with raw material, meat and bones. Then steam from the boiler is admitted into the sterilizer through valve \(m\), as a result of which the material is heated and gives off part of the water contained in it. This water, mixed with condensed water from the introduced steam and with part of the fat that has separated out, flows through valve \(c\) into vessel \(e\). Here the fat is separated from the water, and this latter is distilled over, upon opening valve \(f\), into evaporator \(g\) by the force of the steam pressure present in \(a\). As soon as such a quantity of water has passed into \(g\) that the steam coil is covered by it, the steam valve \(m\) is closed, coil \(h\) is put into operation, and thereby the water present there is converted into steam. This steam, through pipe \(i\), passes via valve \(k\) into sterilizer \(a\) and acts upon the material being processed, steaming it and decomposing it into its constituent parts. The liquid elements released in this process continually flow into vessel \(e\), from which the glue water that separates out is from time to time distilled again into vessel \(g\).

Thus, for the formation of the steam acting in the sterilizer, water extracted from the material being processed is used, so that no artificial dilution of the glue liquor occurs, unless one counts the fresh steam introduced at the very beginning through valve \(m\). From the foregoing it is also clear that the water separated from the meat parts passes repeatedly through the evaporating apparatus, and that, with sufficiently prolonged evaporation, only glue syrup remains in \(g\), while in vessel \(e\) there collects pure water, free from glue.

To accelerate the steaming process, while it continues, drum \(a\) is set into a slow rotary motion, whereby the steam each time comes into contact with new portions of the material. Upon completion of the steaming, valves \(k\) and \(c\) are closed, and the steam released in vessel \(g\) is admitted through valve \(l\) into steam jacket \(b\). The water condensing in the latter flows further through valve \(d\) into vessel \(e\). By heating the steam jacket containing the drum ...

the steamed material is dried; at the beginning of this process the valve u is opened, and the vapors released from the material are drawn out through an exhaust pipe by means of a fan or an air pump. At the same time the drum a is set into more vigorous rotation, as a result of which, as drying continues, the material is pulverized and passes, in greater or lesser part, through the holes of drum a into the space between the latter and the steam jacket. Fat and glue from vessels c and g are discharged through cocks. The drum bearing is arranged in such a way that the entire apparatus can be turned over with the receiving opening downward.

The Joint-Stock Company for Drying Slaughterhouse Waste in Cassel has designed an apparatus for the utilization of slaughterhouse refuse and animal carcasses according to Otte’s design (Cadaver-Verwerthungsapparat System Otte). The principal part of the Otte system apparatus is the sterilizer shown in drawing 30. In it, the material intended for processing (carcasses, parts of carcasses, meat waste) is boiled, dried, and crushed, and thus leaves the apparatus in the form of a dry, loose substance ready for sale.

The devices by means of which this is achieved are as follows. In a cylinder with double walls there rotates a perforated drum c, which receives the material being processed. The material is loaded through an opening in the walls of the outer cylinder and the corresponding opening of the drum, closed by a slide gate. For introducing larger parts, for example uncut carcasses, the covers opposite the drive are opened, both of the outer cylinder and of the perforated drum. In the drum lies a freely moving leather-covered roller d, which, with each revolution of the drum, rolls along it and crushes the boiled material. On the outer surface of the perforated drum a large number of paddles are placed, arranged along a helical line; they serve for stirring and moving the dry product that sifts through the openings of the drum.

The pipe designated in the drawing by the letter h serves to conduct steam into the apparatus; pipe g introduces steam into the steam jacket, while pipe i serves to carry off vapors and gases released during the drying of the product. Through pipe k the liquid substances released from the material being processed—fat and glue water—are removed. The drum is riveted from iron sheets 5 mm thick and mounted on a solid shaft, calculated so that, when completely filled, no deflection of the drum or shaft occurs. The shaft rotates on one side in a bearing that closes from the outside.

a bushing; on the drive side it likewise passes through a stuffing box. On the shaft there is mounted (on the left) a wheel with curvilinear teeth, about 600 mm in diameter, serving to set the perforated drum in rotational motion. At point c of the cover of the outer cylinder there is an hermetically closing opening, through which, after the whole operation is completed, the animal meal is raked out.

Besides this principal apparatus, the sterilizer, the Otte system also includes other auxiliary apparatuses intended for receiving the liquid substances, fat and glue liquor separated from the material, and for subsequent operations with them. These apparatuses are shown in Fig. 31, which schematically represents the arrangement of the entire system in general. The letters A, B, and C denote the sterilizer, receiver, and glue evaporator; G denotes the steam engine, and E the air pump connected with this engine. Of the indicated vessels, receiver B serves for the direct reception of liquid products, while apparatus C serves for receiving and drying, from time to time, the glue liquor distilled from the receiver. The conversion of water into steam is carried out by means of the steam coil n, heated by fresh steam from the boiler. D is a high-mounted reservoir for water, corresponding in size to the number and dimensions of the sterilizers and likewise equipped with a coil for heating. F is a reservoir with water, which serves for the condensation and absorption of vapors and gases released during the drying of products in the sterilizer and evaporator.

Processing in the apparatus of the Otte system is carried out in the following manner (cf. Fig. 31). Through the hatch and the corresponding opening in the perforated drum, the material is loaded into this latter by means of a large funnel. Since, in the Otte system, sterilizers are usually installed in the basement of the slaughterhouse, filling takes place directly through openings in the slaughterhouse floor situated precisely above the openings of the sterilizers.

In general, this method of filling may be considered the most convenient. In slaughterhouses it is most often necessary to deal with separate parts of slaughtered animals that are excluded from circulation and set aside for rendering harmless. When processing fallen but not infected animals, the hide is removed from them, and then the carcass, by means of several manipulations with knife and axe, is divided into parts that would pass through the opening. But if one has to deal with the carcasses of infected animals, it is necessary, in accordance with the requirements of sanitary supervision, to introduce

such carcasses into the sterilizer uncut. For this case the side cover of the outer cylinder of the sterilizer and the corresponding bottom of the perforated drum are arranged in such a way that they can be removed by the method shown in Fig. 32. Since, when the cover is removed, the drum is deprived of one of its points of support, a wedge supporting the drum during the operation is first inserted through the emptying hatch. Then the screws closing the cover of the cylinder are unscrewed, the cover is lifted by a hoist and moved aside. The bottom of the perforated drum is provided at its lower end with a hinge, so that it can easily be thrown back when the slide arranged above is opened. After this a special incline is set against the opened sterilizer, along which the carcass slides in a trough into the drum. The trough is made like a little sled and is supplied at one end with a strong spring fastened to the lower end of the incline. First this spring is stretched by pulling the trough upward; the latter is secured by the corresponding device and the carcass is placed on it. When the fastening at the upper end of the incline is released, the trough slides down it at great speed and, before entering the drum, strikes a buffer device, as a result of which the trough itself immediately stops, while the carcass lying on it, owing to inertia, slips from it into the drum. After this the apparatus is closed and screwed up. Introducing a whole carcass into the apparatus requires, including unscrewing and screwing up the cover, about 20 minutes in all.

After the disinfector has been filled, the openings are hermetically closed, and by opening the corresponding valve steam is introduced into the interior of the apparatus. This begins the steaming process, which requires, depending on the properties of the material, 3, 4, sometimes \(4 \tfrac{1}{2}\) hours. If the material being treated is very rich in fatty substances, it is recommended to continue the steaming for another half hour. The liquid products extracted in this process—fat and glue liquor—flow through the openings of the drum, collect in the lower part of the outer cylinder, and gradually pass through pipe \(k\) into receiver \(B\). In general, during steaming the drum remains at rest, in order to facilitate the separation of fatty substances from the general mass. Sometimes, however, depending on the properties of the material being processed, it is recommended to turn the drum from time to time once or twice, in order to expose new surfaces to the action of the steam.

At the end of the steaming process, drying begins by stopping the inflow of steam into the cylinder and introducing it into the steam jacket. At the same time the perforated drum is set in rotary motion by means of transmission \(h, i\) (Fig. 31), and ...

in such a way that it makes, alternately, a complete revolution in one direction and then in the other. With such an oscillatory motion, the contents of the drum move from place to place, while the roller rolling inside the drum makes its way through the softened masses of flesh and bone. At the same time, owing to the presence of openings in the drum, the roller crushes the material to such an extent that, during the drying process, the latter is ground down, passes through the openings of the drum, and, coming into direct contact with the heated steam jacket, is finally dried.

The drying of the product, which upon leaving the drum already has the appearance of a powdery mass, is substantially accelerated by the fact that it is stirred by blades located on the outer surface of the drum and is moved from place to place during the oscillatory motion of the drum. In this way, separate portions of the substance being dried come into contact with ever new points of the heated surface. The energy and speed of drying are further increased by the fact that the gases and vapors released from the material during this process are drawn off by an air pump. After \(3 \tfrac{1}{2}\)—\(4 \tfrac{1}{2}\) hours the drying process is completed, so that all the material is in the lower part of the sterilizer, between the perforated drum and the outer cylinder, in the form of the finished product. Its removal is then accomplished by opening the discharge hatch, which until then has been hermetically closed, and by rotating the drum in one direction, while the stirrers on its outer surface themselves push out the animal meal.

The liquid constituent parts of the carcasses flow down throughout the entire steaming process through the transfer pipe \(K\) into the receiver \(B\). They consist of fat and water containing \(10\)—\(12\%\) of all possible organic and inorganic constituent parts of the meat and bones, among which glue occupies the chief place. In the receiver, the fat and glue are separated from the meat liquor according to the specific gravities of the liquids. The heavy glue syrup descends to the bottom, while the fat floats to the surface. This process of separation is, of course, carried out the more easily the less the liquids have been mixed with one another. Every motion of the liquids gives a more or less strong emulsion, from which the fat separates only with great difficulty and very slowly. For this reason, methods in which the liquid products are from time to time driven from the sterilizer into the receiver by means of steam pressure are inconvenient. In the Otte system, instead of periodic discharge, in which the favorable conditions for the separation of the emulsion are disturbed, a continuous flow of the liquid ...

of substances. This becomes possible because the sterilizer $A$ and the receiver $B$ are under one and the same pressure, and thus the draining and separation of the liquids proceed exactly as they would if the entire process took place at ordinary atmospheric pressure.

When enough glue liquor has been separated into the receiver, as may be ascertained from the water-gauge glass, then, by opening the valve $m$, it is forced by pressure into the glue evaporator $C$, where it is thickened by heating with a steam coil. Of course, the valve must not be opened at once, so that the fat will not mix with the glue liquid. The fat is drained from the receiver $B$ by means of the movable pipe $l$, while the thickened glue is discharged through the tap $o$.

The gases and vapors given off during the drying of the solid products and during the thickening of the glue are subjected successively to condensation, absorption, and incineration. By means of the air pump $E$, the vapors and gases are driven from the sterilizer $A$ and the glue evaporator $c$ into the reservoir $D$, where they are condensed in a cooling coil. At the same time, the aqueous vapors condense and, in the form of droplets, absorb part of the gases traveling with them. In order to separate the remaining portion of the gases capable of absorption, the discharge pipe of the coil is introduced into the closed reservoir $F$ with running water in such a way that its end is immersed in the water. The gases that have passed through the water without being absorbed are conveyed, by means of a small fan, through a pipe passing through the hermetic cover of the reservoir $F$, into the furnace of a boiler, where they are released in fine streams from a special box and burned.

At the end of all the operations, there is obtained from the drum $e$ animal meal, from the pipe $l$ fat, and from the tap $o$ raw glue. The animal material introduced into the apparatus thus appears again in the form of three finished products: animal meal, fat, and glue. Establishments for the sterilization and processing of confiscated materials and animal carcasses, equipped with Otte apparatus, exist in the cities of Altona, Angalt, Hanover, Pomerin, and others.

The undeniable structural merits of the apparatus of the Otte system attracted the attention of the firm Rud. Hartmann, which had always worked seriously in this field. Taking advantage of the fact that this apparatus has many features in common with the utilization apparatus described above, designed by the firm itself, it found it possible to make use of the best features of both systems in order to create a new, more perfect device. Such a device, representing a combination of the Hartmann and Otte systems, was issued under the name of an apparatus for the destruction, processing, and drying of carcasses and refuse,

of Hartmann’s system (Cadaver-Vernichtungs- und Verwertungsapparat System Hartmann-Trebertrocknung). We consider it more just and convenient to call this new apparatus the Otte-Hartmann system.

The utilization apparatus of the Otte-Hartmann system is shown in its complete form in drawing 33. It consists of three separate vessels connected to one another by the corresponding pipelines. The largest of the vessels is actually the sterilizer and drying apparatus, in which the meat and bone masses are steamed, decomposed, and finally processed into animal meal suitable directly for sale. The liquid substances extracted from the material flow out through the openings of the perforated drum, but are not collected in the lower part of the outer cylinder with double walls; instead they flow into the second vessel, the receiver, where the fat and the gluey liquid separate from one another. The gluey raw material is then driven into the third vessel, the evaporator, where it is evaporated by heating with a steam coil.

A substantial advantage of the system described is the extensive use of secondary steam. In the present case, for steaming the material, the steam used is not steam from the boiler, but steam obtained from the evaporation of the gluey liquid. For thickening the gluey liquid, boiler steam is of course used. But the latter enters only the interior of the evaporator coil and gives up its heat there for thickening the gluey liquid, without mixing with the latter, and then itself condenses in a pure state. In this way, the steam obtained from the gluey liquid is also used for drying the boiled material. To achieve this purpose, a pipe x is led from the evaporator to the extraction apparatus, branching farther on into two pipes. Of these, one, closed by valve b, goes directly into the disinfecter, i.e. to the raw material; the other, closed by valve i, conducts the steam into the steam jacket c surrounding the whole apparatus. Thus, by means of these tubular connections, the steam formed during the evaporation of the gluey liquid may be used, as desired, either for directly steaming the meat parts or for heating the jacket c, i.e. for drying the products located in the apparatus.

For receiving the raw material there serves a rotating perforated drum l arranged inside the sterilizer. It is closed by a lid consisting of several parts and is provided on its outer surface with a large number of stirrers e, which move the material that falls during the process of drying and rotation of the drum over the inner heated surface of the steam jacket and grind it into powder. The whole apparatus is closed by a large

with a cover \(a\) of such dimensions that the inner drum is inserted through the opening of this cover and can be taken out through it in case of repair.

The apparatus is made in various sizes, for a useful capacity of 500, 750, 1000, 1500, 2000, and 2500 kilograms. In the larger sizes of apparatus, the opening of the cover has such dimensions that through it it is possible to introduce the whole carcass of large cattle in an undivided state. In the smaller apparatuses this opening is nevertheless so large that the carcass of an adult pig can be introduced without being cut up. The cover \(a\) hangs on chains and is raised by means of a winch arranged at the side. At the same time the pipe \(y\), running upward from the cover, extends like a telescope, without breaking the connection. Besides the perforated drum, which is set into rotary motion by the transmission located at the side, the sterilizer itself can rotate as a whole about its axis by means of a toothed connection, so that the opening closed by the cover \(a\) can be turned downward, which is necessary when emptying the apparatus of its contents. This rotation of the apparatus is also intended to facilitate loading. The filling opening \(a\) is turned obliquely to the side, and then it is easy to reach it from the floor.

The pipes \(i\) and \(k\), leading into the steam jacket \(e\), are introduced into the apparatus through stuffing boxes, so that they do not hinder its rotation. The pipes \(b\) and \(l\) are connected with the apparatus by branch pipes and must therefore be disconnected at each rotation, which, however, presents no great difficulty.

The process of operation in the Otte-Hartmann apparatus begins, of course, with the loading of the material. For this purpose the cover \(a\) is raised upward by means of the winch. Then the cover \(d\) of the perforated drum, consisting of several parts, is removed, and the whole apparatus is turned enough so that the loading hatch no longer lies beneath the raised cover \(a\). Then pieces of carcasses of any size, as well as uncut carcasses, are placed inside the drum until it is filled. After this the drum covers are put back on and closed, the apparatus is again set upright, the cover \(a\) is lowered and tightly pressed on by a row of edge bolts. When the pipes \(b\) and \(l\) have then been connected to the apparatus, steam from the boiler is admitted through the valve \(v\) into the coil \(q\) of the evaporator. This steam has a pressure of about 5 atmospheres and in a short time evaporates the glue liquor left in the evaporator from the preceding operation. The steam thus obtained is then conducted through the valves \(x\) and \(b\) to the raw material, and the steaming of the latter begins. The liquid portions thereby separated—fat, meat broth, glue—

liquid, flow through the cocks \(f\) and \(m\) into the receiver \(p\), where the fat separates from the glue.

When it is seen through the gauge glass that a sufficient quantity of glue has been expressed into the receiver, cock \(t\) is opened, valve \(x\) is closed, and, through valve \(u\), a little steam is admitted from the boiler into the sterilizer, in order to establish in it a higher pressure than in the evaporator. By this increase of pressure the glue liquor located beneath the fat is driven from the receiver through cock \(t\) into the evaporator, to such an extent, of course, that part of the fat cannot leave with it. Then valve \(u\) is closed, valve \(x\) is opened, and the glue liquor is evaporated as before in vessel \(q\), while the steam that is evolved is led off into the sterilizer.

Of course, the steam penetrates not only into that part of the material which lies directly on the walls of the perforated drum, but also reaches the parts lying farther inside the drum. To facilitate the access of steam, it may be recommended to rotate the drum several times. The steam from the boiler enters the coil of the evaporator, as mentioned earlier, at a pressure of 5 atmospheres. It goes without saying that the steam released from the glue liquor has a somewhat lower pressure, but nevertheless it reaches 4 atmospheres. After 4–5 hours this steam brings the material being treated to complete decomposition and frees it from the greater part of the water and fat contained in it. Toward the end of the process, therefore, the products of extraction, fat and glue, are found respectively in the receiver and the evaporator, while inside the drum there remain the residues of the charged material.

At the end of the steaming process, the drying of the residues of meat and bones located in the drum is begun. For this purpose, first of all, the glue liquor that has collected in the receiver is distilled into the evaporator, and valve \(b\) is then closed, in order thereby to stop the inflow of steam to the contents of the sterilizer. At the same time cocks \(f\) and \(m\) are closed and valves \(i\) and \(k\) are opened, so that steam from the evaporator enters the steam jacket \(c\) and, giving up its heat, dries the contents of the apparatus, while it itself condenses. The condensed water flows through the pipe and valve \(k\) into the receiver, washes the fat collected there, and finally collects in the space that had earlier been occupied by the glue liquor. This water, being a product of distillation, is relatively pure in comparison with the glue liquor. Of course, it contains contaminating elements which originate from the organic substances and the decomposition products of the glue liquor, and, moreover, from the separation of the layer of fat through which it ...

simpler. The composition of this water, on the basis of the analyses performed, is in general as follows:

Component	Amount
Dry residue	0.29%
Ash	0.01
Organic substances	0.28
Total amount of nitrogen	0.14
Organic nitrogen	0.01
Specific gravity	1.001

Thus this water is relatively pure and in itself quite sterile.

The perforated drum rotates throughout the entire drying process, as a result of which the soft fleshy and bony masses rub against one another, are comminuted, and gradually fall through the openings of the drum. Here, in the space between the drum and the steam jacket, they are caught up by paddles, are gradually further comminuted and are moved directly toward the hot walls of the jacket. The rotating drum thus effects both the drying and the grinding of the product.

The vapors released during the drying of the material are drawn off by a small fan through the valve of the cover and the pipe $y_1$. If fresh material is being processed, the odor issuing from these vapors is not too unpleasant and somewhat resembles the smell of meat broth. If, however, the raw material has decomposed to a greater or lesser extent, the vapor released has a very unpleasant odor, which must necessarily be removed. For this purpose there is a special chamber with a sprinkling condenser, in which the water vapors and part of the gases are condensed and absorbed, while the remaining gases are led under the firebox of the boiler.

The drying process usually requires about 4 hours. By its end the glue liquid that was in apparatus $q$ has evaporated, and the water used in the form of steam is in the receiver below the fat. In the sterilizer there is a powdery, completely dry mass—animal meal. The residue in the evaporator is a syrup-like viscous mass, consisting chiefly of glue and containing, in addition, a considerable admixture of substances of organic and inorganic origin. We shall discuss the use of this so-called glue syrup below.

The preceding description shows that the condensation of the vapors released from the glue liquid takes place in a space closed on all sides; that no excess water is used in this condensation; and that the heat of the condensed vapors is used for drying the animal meal. It should further be noted that, for steaming the raw material, no steam from the

the boiler, and that the glue liquid flowing off during the course of the process is not diluted with water from steam condensation. It is clear that such a method of operation, while very fully attaining the aim and eliminating the odor, brings a great saving in coal.

Upon completion of the entire process, in order to empty the apparatus, the cover $a$ is raised, the tubes $l$ and $b$ are detached, and then the whole cylinder is turned, as described above, around its axis until the charging opening is at the bottom. The animal meal lying in the space between the drum and the walls of the cylinder is, for the most part, poured out by this manipulation without outside assistance. The remainder is discharged outward by special brushes attached to the drum before emptying, by further rotation of the drum. By this time there remains inside the drum only a quite insignificant quantity of pieces of bone and tendons, which are nevertheless so dried that with little difficulty they can be ground in a mill.

The fat is discharged through the cocks $n\,n$ arranged on the receiver, and the glue is let out through the cock $s$. The condensation water that has collected beneath the layer of fat is discharged into the sewer, except for a small quantity needed for resuming production the next time.

The so-called raw glue discharged from the evaporator is, as mentioned above, a product which, besides glue, contains a considerable quantity of special foreign substances extracted from the meat and bones. Therefore the calculation for processing this material into hide glue usually is not justified, because purification is too expensive, not to mention that, from heating the glue substance to high temperatures, it loses somewhat in its gelatinous properties. In general, glue obtained from this material has limited application as a second-grade product, and therefore the revenue from its sale is very doubtful. It therefore proves more advantageous to use it by adding the glue syrup to the meat-and-bone mass being boiled in the disinfector and, together with this mass, subjecting it to drying and conversion into animal fat. Unfortunately, in this direction as well, hopes are not entirely justified, since specialists, on the basis of experiments, show that an admixture of glue substances in fodder fats has an irritating effect on the digestive organs of domestic animals.

The substantial advantage of using exhaust steam is demonstrated by the circumstance that the working steam coming from the steam boiler gives up in the coil $q$ (Fig. 33) exclusively its latent heat—

Plate 1.

Drawing 1. Reconstruction of the “Reum.” system

Section along \(cd\).

Section along \(ab\).

Scale: \(1{,}00\), \(0{,}50\), \(0\), \(1{,}00\), \(2{,}00\ \text{m}\).

Plate 2.

Drawing 2. Distributor of the Kreiger system (diagram).

[Diagram with labels: A, B, C, D, E.]

[Scale: 1.00, 0.50, 0, 1.00, 2.00, 3.00 m]

Drawing 3. Distributor of the Borden system (diagram).

[Diagram with labels: b, B, C, D, E, F.]

[Scale: 1.00, 0.50, 0, 1.00, 2.00, 3.00 m]

Plate 3.

Doors

Drawing 4.  Drawing 5.

Fire grates

Drawing 6.  Drawing 7.

Movable grates

Drawing 8.  Drawing 9.

Giffard injector

Drawing 10.

Drawing 11. Kerting injector.

Table 4.

Drawing 12. Fibrich through-type stalls at the Munich slaughterhouse.

(1/250 full-scale.)

Longitudinal section.

Plan.

Section along CD.

Section along AB.

Table 5

Fig. 13. Delacroix disinfection system.

Fig. 14. Rietschel and Henneberg vacuum-disinfection system.

Table 6.

Fig. 15. Plan of a utilization device with the Ritschel and Henneberg apparatus.

(1/150 natural size.)

Fig. 16. Drying apparatus of the Otte system.

Table 1.

Approximate design layout of a shaft gasifier according to AKSO
with a chamber furnace and [[unclear: handwritten phrase]].

Fig. 15.

Variant according to AKSO

Plan

Variant according to [[unclear: abbreviation]]

Variant according to [[unclear: abbreviation]]

Variant according to [[unclear: abbreviation]]

Fig. 16.

Plate 8.

Dry apparatus of the Rittinger and Henneberg system.

Fig. 17. Fig. 18.

Fig. 19. Disintegrator of the Rittinger and Henneberg system with a drying centrifuge.

Plate 9.

Fig. 20. Extraction apparatus, Barshman system (vertical).

Fig. 21. Extraction apparatus, Barshman system (horizontal).

Scale: 1.00, 0.50, 0, 1.00, 2.00 m.

Plate 10.

Fig. 22. Drum of the Podéwils-system utilization apparatus. (Side view.)
(3/100 of natural size.)

Visible diagram labels: a, b, c, d, f, h, C, D.

Table 11.

Fig. 23. Utilization apparatus of the Podewils system. (Section.)

(1/50 natural size.)

Table 12.

Fig. 24. Podewils-system utilization apparatus. (General view with part of the machine room.)

Plate 13.

Fig. 25. Tilting drum of the Podevils system.
(Top view.)
(3/100 of actual size.)

Table 14.

Fig. 25 a. General view of part of the proving ground for the disposal of ammunition at the Dresden plant.

Table 15.

Drawings 26—28. Utilization chamber at the Yuryev slaughterhouse.

\((1/120\) of natural size.)

Cross section.

Longitudinal section.

Plan.

A—Podévil’s drum.

Б—pressure vessel.

Г—condenser.

Д—gas holder.

Е—water receiver.

С—refrigerator for fat.

Ф—barrel for fat.

Table 16.

Drawing 29. Utilization apparatus of the Hartmann system.

\((1/100\ \text{natural size}.)\)

Drawing 30. Sterilizer of the utilization apparatus of the Otte system.

\((1/50\ \text{natural size}.)\)

Fig. 32. Loading the Otte apparatus with slaughterhouse carcasses.