Proceedings of the Tomsk Technological Institute

of Emperor Nicholas II.

Vol. 16. 1909. No. 4.

III.

S. V. Lebedev.

Report on an International Business Trip.

1—42.

REPORT

ON AN INTERNATIONAL BUSINESS TRIP

S. V. Lebedev.

The plan of studies of each person sent on a business trip is determined by the tasks of those scientific and technical fields that fall within his specialty.

This question, which is resolved comparatively easily in purely theoretical specialties, proves to be rather complex in the case when one has to deal with technologies encompassing a number of technical industries that differ sharply from one another both in their theoretical basis and in the principal methods of factory practice employed, as well as in the technical conditions under which one or another process of the various industries takes place.

Therefore, in order to make the plan of my studies comprehensible, I must first dwell on the technology of nutritive substances, which is my specialty.

The industries embraced by the above-mentioned technology are characterized by the fact that all of them work with carbohydrates extracted in one way or another from the material being processed—agricultural products, such as grain bread, potatoes, sugar beet, etc.

The industries belonging here may be divided into two essentially different groups.

The first of these includes industries whose purpose is only to extract from the material being processed certain carbohydrates. In this case, the task is, in addition, to purify the extracted carbohydrate from foreign substances and to give the resulting product one form or another convenient for handling. Sugar and starch manufacture belong here.

The second group is covered by the technique of fermentation, which pursues not only the fullest possible extraction, but also a more or less profound change in the chemical nature of part or all of the carbohydrate that is the object of the given industry.

At the basis of the factory operation of the industries of the first group lies a series of purely physical processes, such as: diffusion, evaporation, crystallization, steeping, etc.

In connection with these fundamental physical processes there stand certain chemical ones, the aim of which is the purification of the extracted carbohydrate from foreign substances that pass into the products of manufacture from the material being processed. The character of such chemical processes may be very varied and is determined in each individual case by the chemical nature both of the carbohydrate being extracted and of the substances being removed.

At the basis of the second group of industries, embraced by the technology of fermentation, lie enzymatic work and biological processes connected with the vital activity of known microorganisms. The physical processes applied here as well—distillation, filtration, etc.—have as their aim the purification of the products obtained.

Thus, in addition to chemistry, upon which all chemical industries in general are based, the fundamental elements for the technology of foodstuffs in particular are: enzymatic work, special questions of microbiology connected with the technology of fermentation, and the analysis and development of the fundamental physical and chemical processes under those special, often entirely distinctive, conditions that are created by the technique of production.

In accordance with what has been said, in making use of the business trip I set myself the following tasks:

a) Work in special institutes directing one or another technical production of food technology.

b) The study of modern practical procedures and scientific methods of research employed in laboratories working on the elucidation of various biological processes related to the technique of fermentation.

c) Visiting, inspecting, and, where possible, carrying out practical work at the various factories belonging to this field.

The distribution of the time of the trip among the above-outlined tasks is determined in each individual case by the degree of preparation of the person sent on the trip in the various areas of his specialty, and also depends on reasons of a purely local character; for this reason, for example, in the present case it was necessary to devote more time to the technique of fermentation than to the other industries, since the latter, for Siberia, at least in the present and the near future, are of less significance than the technique of fermentation.

In carrying out the planned program of work, it is of course also necessary to reckon with the possibility of obtaining a place for study in the laboratories indicated.

I began my studies in the zymotechnical laboratory of Alfred Iörgensen, “Gärung-physiologisches Laboratorium,” Copenhagen, Frydendalsvej Str. 30.

The indicated laboratory is a private enterprise, the founder and owner of which is Iörgensen, the director of the laboratory. The latter pursues a twofold aim, and accordingly consists of two divisions: a technical one and an instructional one.

The technical division, under whose constant supervision are the majority of Danish and several foreign breweries and distilleries, is engaged in preparing pure cultures of yeasts for sale and in developing such strains as would meet one or another requirement of practice.

The staff serving this division of the laboratory consists of 4 assistants, one of whom is, in most cases, traveling among the factories under supervision. The laboratory has at its disposal 4 attendants and one errand boy.

The instructional division is headed by Dr. Holm, who, together with his assistant Dr. Blom, directs the work of the trainees. The latter usually constitute a rather diverse group of 10–20 persons interested in methods for studying lower organisms and in methods for obtaining pure cultures. At the same time, the majority of the trainees are present or future brewers.

The instructional division is of the same size as the technical one; it is housed in 3 small rooms, besides which another 3–4 rooms belong to the laboratory, intended for washing glassware, preparing nutrient solutions, sterilization, packing, etc.

Directly connected with the laboratory is a spacious room, 1½ stories high, along whose walls are arranged a large number of shelves, where yeast cultures are kept in Carlsberg flasks. This room, distinguished by exceptional cleanliness, has steam heating, and its temperature is strictly maintained at 15°C.

In the instructional division of the laboratory described, over the course of 3 months I was given a systematic course on methods for studying microorganisms of importance in fermentation technology, and on methods for preparing pure cultures.

The 20-year uninterrupted activity of this laboratory has given it great pedagogical experience and the opportunity to set up, in exemplary fashion,

exercises, as a result of which the time of the worker here is spent surprisingly purposefully and productively.

The exercises begin with acquaintance with the most common molds, such as: Oidium, Penecillium, Mucor, Thomnidium, Cladosporium, Botritis, Dematium, and others. Work with these molds gives the trainee the opportunity and the ability to recognize these organisms, harmful in practice, which often contaminate the yeast being used and cause undesirable changes in fermentation products.

In these works three kinds of cultures are established: on beer wort in a Freudenreich flask, in a moist chamber (with threefold dilution), and on wort gelatin in a Petri dish for macroscopic examination. The cultures are placed in a thermostat, and over the course of several subsequent days the gradual development of the inoculated organisms is observed daily. The subculturing of the cultures is carried out in a special glass cabinet (70 × 45 × 60 cm) with a movable, sliding front wall.

Before work is begun in it, the cabinet is first sterilized from within with a solution of sublimate (1:500). Glass rods and all instruments needed for inoculation, after being sterilized in the flame of a gas burner, are placed in the inoculation cabinet. After this, the inoculation is performed with the front wall of the cabinet extended only so far as to make it possible to insert the hands for carrying out the necessary operations.

Having become acquainted, on the organisms listed, with the development of vegetative cells and the separation of conidia, they proceed to fungi whose forms are close to yeasts, such as: Monilia, Chalara, Mykoderma, Torula, Saccharomyces apiculatus. After this follow the true species of Saccharomyces—first wild ones (Cerevisiae pastorianus, ellipsoideus, fragilis, Ludwigii, membranifaciens, anomalus exiguus, and others), and then also the races of cultivated yeasts (bottom beer yeasts—Münchener, Frohberg, Dortmund, Saatz, and others; then top beer yeasts and, finally, wine yeasts).

In studying yeasts, alongside observation of the development of vegetative cells, the conditions and rate of spore formation are determined. For this, the sediment of a yeast culture, after as much excess liquid as possible has been poured off from it, is transferred in an amount of 2–3 drops onto a gypsum plate placed in a Petri dish, into which, after the yeast has been applied, a small quantity of distilled water is also poured in order to maintain the necessary humidity.

The small cups prepared in this way are placed in thermostats at 15 and 25°C, and then the time of spore appearance is observed daily.

The form of the spores and the rate of their appearance are a very characteristic feature for the different races of yeasts.

After work with yeasts, the trainee becomes acquainted with certain bacteria that are of importance in fermentation technology, such as: acetic-acid and lactic-acid bacteria, some species of Sarzina, Pediococcus, etc.

When the trainee has sufficiently familiarized himself with the organisms listed, he is given a series of analyses (from 30 to 60). The first analyses contain 1–2 species, the last 3–5. Then various factory products of brewing and distilling production are examined—infected beer, wine, and vinegar.

After the analyses, work begins on obtaining “pure cultures,” i.e., obtaining, in a given quantity, yeasts that are the progeny of a single yeast cell.

The work begins with acquaintance with Hansen’s “dilution method.” For this purpose, from the culture at hand 1–2 cc are taken into a Freudenreich flask with 20–30 cc of sterilized water. The flask with the freshly inoculated yeasts is shaken very thoroughly in order, as far as possible, to break up into individual cells the chains of yeasts present there; after this, with a platinum loop, a drop of the shaken liquid is taken and transferred to a cover glass on which a grid of 9–16 small divisions has been engraved, with the entire droplet having to fit within the limits of the indicated grid. Having placed the cover glass with the liquid applied to it into a moist chamber, it is examined under the microscope and the number of yeast cells in the drop taken is counted. After this, a new Freudenreich flask with 20–30 cc of sterilized water is taken, and with a platinum loop enough droplets are introduced into it from the preceding Freudenreich flask to obtain in the latter flask such a dilution that each drop of liquid would contain approximately one yeast cell.

The flask inoculated in this way, for a more uniform distribution of the cells in the liquid, is subjected to ten minutes of shaking, after which the inoculated liquid is distributed, one drop at a time, by means of sterilized pipettes into 50–100 or 150 Freudenreich flasks containing sterilized wort. The latter, after inoculation, are placed in a thermostat at a temperature of 25°C.

After 48 hours, one can already observe in them, with the naked eye, developed colonies situated at the bottom of the flasks in the form of small white specks. At the same time some flasks prove not to be infected, others have one colony each, and still others two or more colonies each.

By selecting flasks that have one colony each, and propagating the cultures by transferring them from Freudenreich flasks into larger vessels with sterilized wort, pure cultures of yeast are obtained by the so-called “dilution method.”

Although in individual cases the indicated method gives good results, nevertheless in general it cannot fully ensure a truly “pure” culture, since in this case there is no sufficiently reliable guarantee that the single colony in one or another selected Freudenreich flask has in fact developed from one cell, and not from a large number of undivided or adhering yeast cells.

Therefore an improvement of the indicated method was necessary, and it is provided by the use of solid substrates, whereby the cells are fixed in solidified wort-gelatin; this makes it possible constantly to observe the development of the colonies and to choose for inoculation those among them which have in fact developed from a single cell.

Those working in the aforementioned laboratory become acquainted with this method, proposed by Stierner and improved by Koch, in the modification of it which was developed for yeasts by Hansen.

In the present case this method is usually applied to the culture which the trainee himself has previously obtained by the described “dilution method.”

From this culture there is introduced into wort-gelatin, heated to the melting point, in a Freudenreich flask, such a quantity that in a drop of the latter, taken with a glass pipette, there would be no more than 10–15 yeast cells. After this, from the Freudenreich flask infected in this way, a drop is taken with a small glass rod and is quickly spread, in as uniform and thin a layer as possible, on a cover glass with a grid etched upon it, the divisions of which are numbered. The cover glass, placed in a moist chamber, is examined microscopically. The observed microscopic picture is accurately transferred to paper ruled in correspondence with the grid of the cover glass. At the same time individual cells lying separately are found and marked.

yeast, which after 2–3 days grow into colonies visible to the naked eye. Each such colony, together with the small piece of sterilized wire gripped in tweezers, is transferred, with all proper precautions, into a flask with nutrient medium, into which the aforementioned wire with the colony upon it is dropped; the latter then develops here over the course of 2–3 days in a thermostat at 25°C. If, when transferring the colony from the moist chamber into the wort, no accidental contamination has occurred, the result is indeed a “pure culture,” i.e., one that has unquestionably developed from a single cell.

After 2–3 days the sediment that has formed is checked under the microscope, and, if there is no contamination, the culture from the Freudenreich flask is transferred into a Pasteur flask with 125 c.c. of sterilized wort, where fermentation lasts 4 days at 25°C. Then the yeasts obtained in this way are used to inoculate 500 c.c. of wort in a large Pasteur flask, which is likewise left to ferment for 4 days, but already at room temperature. After four days have elapsed, the contents of the large Pasteur flask are transferred into a Carlsberg metal flask with 7 liters of wort, which ferments for 7 days in a cellar at 15°C.

The commercial yeasts for breweries, sent out by A. Jörgensen’s laboratory, are usually prepared in Carlsberg flasks; after fermentation is complete, the beer from the Carlsberg flasks is drained through the lower opening, and into each flask, onto the yeast sediment, 1/2 liter of sterilized water is added; the flask is shaken vigorously, after which its contents are transferred directly into a previously sterilized shipping flask, the capacity of which usually corresponds to the quantity of yeast from three Carlsberg flasks of the stated capacity.

The finished culture of each Carlsberg flask is first checked by microscopic examination.

The shipping flasks are tin cylinders, provided in the upper part with two copper tubes with stopcocks; the capacity of the flask is about 2 liters.

To sterilize the shipping flasks, water is boiled in them, and then, after closing the stopcocks, they are allowed to cool; in this way the strength and suitability of the given flask are tested, since a vacuum is thereby formed in the latter. Before pouring in the yeast, a sterilized cotton filter is attached to one of the tubes of the shipping flask by means of rubber; by opening the stopcock of the flask, air is admitted into it, which is then blown in through that ...

the same filter, thanks to which the water filling it is displaced from the flask. The transfer flask thus emptied is connected to the Carlsberg flask, likewise provided with a cotton filter, and is gradually filled with yeast. When the flask is filled with yeast, its tubes are flattened close to the stopcocks, which are cut off and twisted into a spiral, whereby complete hermetic sealing of the closure is achieved.

In such transfer flasks, placed in boxes with a large quantity of shavings, the yeast is dispatched everywhere to the factories.

For scientific laboratories and to such countries where a high or excessively low temperature gives grounds to fear for the integrity of the yeast being sent, the latter is sent in Freudenreich flasks on sterilized cotton wool; for this purpose 2–3 drops of the culture are applied to the latter. Under these conditions the yeast can remain for a very long time and rather stably withstand unfavorable conditions.

For trainees, the propagation of pure cultures is usually limited to the large Pasteur flask; subsequent operations can be observed in the technical department.

After preparing pure cultures, the person engaged in this performs a biological analysis of water and air, after which he studies the fauna of one or two or a larger number of varieties of some fruits.

I, for example, studied the fauna of two varieties of grapes, and on one of them yeasts were found, isolated in pure culture, close in their character to Saccharomyces cerevisiae I. With this the trainee’s course work in the laboratory described comes to an end. In addition, I also observed all operations relating to the preparation and sterilization both of nutrient solutions and of glassware in this laboratory.

The methods of sterilization, both in this laboratory and in other similar ones that I saw, are approximately the same and consist of the following.

Glass, metal, and other objects not damaged by high temperature are sterilized in hot-air sterilizers at a temperature of about 150°C for approximately 2 hours. Gypsum plates used for the study of spore formation are sterilized for 1 hour at 110°C; small objects, such as forceps, glass rods, cover glasses, etc.—in the flame of a gas burner; transfer cabinets—by wiping with a sponge moistened...

…with a solution of sublimate (1:500) or with absolute alcohol, which is encountered more rarely.

The nutrient media are for the most part sterilized in flowing steam; the duration of sterilization, depending on the properties of the medium, ranges from \(1/2\) to 1 hour. In this connection the method of repeated sterilization is used, consisting in the fact that sterilization is repeated 2–3 times at daily intervals, during which the media are kept at a temperature favorable to the germination of the spores of microorganisms. Thanks to this, the resistant spore-forming forms of foreign organisms that may be present in the medium being sterilized develop during the daily interval into less resistant ones, which are easily killed by the subsequent sterilization. Large quantities of nutrient liquids are sterilized by direct boiling, and all the openings of such apparatuses—for example, large Carlsberg flasks—are sterilized directly by the steam issuing from the liquid. After sterilization is completed, the upper opening of the Carlsberg flask is connected with a sterilized cotton filter, which then remains in this place during all subsequent work with the flask.

Collections of pure yeast cultures are preserved here at ordinary temperature in a 10% sucrose solution in Freudenreich flasks.

After completing my work in Jörgensen’s laboratory, I inspected the zymotechnical laboratory of Prof. Hansen, now belonging to the Academy of Sciences, which is one of the most extensive and well-equipped institutions of this kind.

In addition, I visited the best breweries here: Carlsberg (old and new), Tuborg, and the small but very well organized Stern brewery, where at that time one could see the preparation of so-called “non-alcoholic beer,” which is wort saturated under pressure with carbon dioxide. This beverage, however, sold very poorly, since, apart from its not especially pleasant taste, it does not at all meet the requirements of refreshment and thirst-quenching, being thick and too sweet.

After Copenhagen I transferred my work on the same question to Berlin. On the way I inspected Schifferer’s brewery in Kiel, known for the exemplary organization of its production control. The plant has a laboratory with a small library, containing everything necessary for biological and chemical control of production. In addition, there are a number of instruments and apparatuses controlling the operation of the steam boilers and

machines. At the factory there are constantly 2–3 trainees, usually the sons of owners of breweries.

In Berlin I worked at the “Institut für Gärungsgewerbe,” See Str. 65.

The history of the emergence of this institute and its departments is inseparably connected with the history of the development of the five German associations adjoining it—of distillers, brewers, starch manufacturers, dry-yeast manufacturers, and vinegar manufacturers. The oldest of these associations, namely the union of distillery owners, in 1874, at Maerker’s proposal, founded an experimental station, which began to develop extraordinarily rapidly. Soon a distilling school was attached to it, and then an experimental distillery. Gradually the station’s activity embraced both the technical and the economic side of this branch of industry. From its initial premises at the Royal Academy, the experimental station in 1882 moved into the premises of the Higher Agricultural School. By that time the station already had its own journal, “Zeitschrift für Spiritus Industrie,” and numbered about 1,200 members. In 1883 the newly founded experimental and instructional station of brewers (“Versuchs und Lehranstalt für Brauerei” in Berlin) joined the organization; it subsequently built an experimental brewery, and the association of starch manufacturers joined as well. The consequence of the accession of the said associations was the need to expand the premises, which was met by the government through the allocation of land for the construction of a special building. By that time the station was also publishing the “Wochenschrift für Brauerei” and had at its disposal such scientific forces as Hayduck, Heinzelmann, Lindner, Parow, Saare, Windisch, and others. In 1892 a special department was built for the mass production of pure yeast cultures for sale. At the same time a technical department was founded, directed by Golsich. In 1899 a department of top-fermenting beer appeared, headed by Schönfeld. In 1903, in addition to the existing school for brewers, special examinations for the diploma of brewing engineers were introduced at the station.

The rapidly developing institution required corresponding premises, and in 1896 the Prussian government granted funds for the extensive building in which the entire institution is now located, whose significance and connection with fermentation technology are ever increasing. In addition to the functions of an experimental institution, the annual training of several hundred workers of all levels for fermentation technology, scholarly activity, and constant supervision of production ...

...many factories, the aforementioned institution always comes to the aid in resolving all manner of special technical questions.

Thus, the brief sketch given above provides an instructive history of the development of an institution of national importance from an insignificant enterprise of private initiative. The existence and wide spread of institutions of the indicated type is one of the features of Western European industry that distinguishes it favorably from our own industry. The close connection of such experimental stations and institutes with the practice of the various branches of industry, out of which they in a sense grow and by which they are nourished, guarantees the vitality of these institutions. If one also takes into account that, under similar conditions, dozens of scientific workers specially trained and engaged solely in this work are occupied with solving the special questions of one or another branch of industry, then it will become clear where the key to the technical progress of Western European industry lies.

In this institution, now called the “Institut für Gärungsgewerbe,” Berlin, See. Str. 65, I spent in all 6 months. I began my work in Lindner’s botanical laboratory, where I became acquainted with the methods of investigation and biological control of fermentation-technology production adopted here. The peculiarity of this school, in comparison with the preceding one, is that inoculation cabinets are not recognized here, being considered superfluous; instead of Freudenreich flasks they work with small pharmaceutical glass jars with cotton stoppers; moist chambers here are replaced by object slides with a ground depression, with the aid of which preparations are made with Vaseline seals according to Lindner’s droplet method. The method consists in the following.

Onto an object slide, around the edges of a ground sector-shaped depression 6–7 mm in diameter, four drops of thick Vaseline are applied crosswise with a brush, after which the depression is covered with a cover glass passed through the flame of a burner. The object slide at the site of the depression is slightly heated from below over a small burner flame, whereby the Vaseline melts and is distributed as a ring in an even layer along the edges of the depression. After this the cover glass is removed and, onto it, with a small steel writing pen, three rows of elongated small droplets are quickly applied, after which one breathes on the depression of the object slide until it...

...separately; it is quickly covered with a cover glass, with the drops applied inward; by pressing it lightly, one obtains, thanks to the Vaseline, a hermetically sealed chamber, in which the microorganisms of the liquid under study develop. Each of the three rows of applied droplets differs from the others in a different degree of dilution of the liquid being examined. The first is applied with the liquid taken directly; the second with diluted liquid, since, after the first row has been applied, 2–3 drops of fresh sterilized wort are placed on the feather; after the second row of droplets has been applied, several more drops of fresh wort are again placed on the feather, the result being a new dilution for the third row of droplets. Thus the indicated method makes it possible to observe the liquid under study in a single preparation at three different dilutions of the investigated liquid. At the same time, among the droplets of the last dilution there are often droplets with two or one inoculated cell. This latter circumstance represents a definite advantage in that it sometimes makes it possible to conclude, solely from the form and character of the independently developed colonies, whether one is dealing with one or with several species of yeast.

Lindner’s drop method has been adopted for investigation by all the laboratories of the “Institut für Gärungsgewerbe.” In addition, it is used there also for obtaining pure cultures, for which such a degree of dilution is necessary that in individual droplets of the last row there would be one yeast cell each—in any case, only such droplets may be started in culture.

In the simplicity and speed of its manipulations, the method just described undoubtedly has a great advantage over Hansen’s, but it is inferior to the latter in the sense of the possibility of infecting colonies intended for pure culture. The reason for this is as follows.

During the interval of time necessary for the development of a colony, some of the droplets dry out, as a result of which the cells of such dried droplets are poorly fixed; consequently, during the operations of transfer they can easily get into the colony intended for pure culture. The Berlin laboratory maintains pure cultures on wort-gelatin, which, in the opinion of some zymotechnicians, is incorrect, since the organisms thus preserved supposedly partly lose some of their properties, which are only with difficulty restored when such organisms are transferred to nutrient media normal for them.

The Berlin laboratory sells, in large quantities, brewing and, chiefly, distilling yeasts of pure cul—

...cultures, of which 15,000 kil. were sold in 1907 alone, chiefly—strains XI, XII, and “M.” In addition, a pure culture of lactic-acid bacteria is also sold here, usually dispatched in so-called “Impfflaschen,” or apothecary bottles (100 cc), closed with an ordinary cork. About 7,000 such flasks were sold in 1907.

Yeasts are dispatched, according to preference, in small glass bottles or test tubes on wort-gelatin, in shipping flasks, or else in tins in the form of pressed yeast. The Institute has several pure-culture apparatuses at its disposal, but works chiefly on one of them, of approximately 200 Lit. capacity, of the Lindner—Pest system.

The preparation of pure-culture brewer’s yeast is carried out as follows.

The wort in the apparatus is sterilized, saturated with air, and inoculated at 17° with fermenting wort from one Carlsberg flask (7 Lit.). During fermentation, which lasts 3–4 days, the temperature of the apparatus is lowered to 6–8°C. The fermenting liquid is blown through daily 3–4 times for 5–10 minutes. On the 4th day, with the fermenting wort from the apparatus, 8–10 hectoliters of fresh wort are inoculated at 5°R in an ordinary fermentation vat. During the first days, blowing-through is performed daily 3–4 times. When the wort in the vat has fermented well, a further 8–10 hectoliters of fresh wort are added to it, and until the 4th–5th day blowing-through is continued in the above-mentioned manner. The temperature of the vat is not allowed to rise above 7°R; under these conditions fermentation ends on the 10th–13th day.

The yeast from the apparatus or vat is sold in pressed form, and before release it is checked by microscopy.

The preparation of pure-culture distillery yeast is carried out at the experimental distillery, which is directed by Prof. Dr. Lange. The mash is prepared in a mash tun with a steam jacket and stirrer. The material used is barley malt, to which a certain percentage of detached malt sprouts is sometimes added. Usually 500 Kil. of supplies are mashed with 2,000 Lit. of water, the amount of which, in all—including displacement of the wort from the spent grains, rinsing of the kettle, etc.—is such that the wort obtained is 7–9° Bal.

Mashing is carried out at 33°R. After saccharification, performed in the usual manner, 1½ buckets of sour mash, previously prepared with an inoculation of a pure culture of lactic bacteria, are added to the mash tun at 42–44°R and with vigorous operation of the stirrer. In

for 3–4 hours the temperature of the mash is kept within the limits of 42–44°R, then raised to 46–47°R and maintained at this for a longer or shorter period, after which saccharification is carried out at 60°R or higher, following which the mash is transferred to a filter tun, from which the wort goes into two fermenting tuns with a capacity of 7–8000 liters, equipped for aeration and with permanent coolers; by the action of these, the wort coming from the filtration tun is cooled to 23°R. When approximately half the wort has been run off, yeast is pitched, and aeration begins, which is repeated periodically. Twenty hours after the start of fermentation, they proceed to separate the yeast in a centrifuge. Before centrifuging, aeration is carried out in order to distribute evenly in the wash the settled yeast. The liquid yeast from the centrifuge is immediately pumped to a filter press, from which it is packed into tin containers previously sterilized by burning with alcohol. The yield of yeast is about 20% of the mashed material.

The yeast added to the leavening vat is taken either in the form of pressed yeast from the preceding mash (2 kil. per 1 centner of mashed malt), or else directly from the pure-culture apparatus. The latter, for this purpose, is inoculated at 24°R with a normal Carlsberg flask and after 2 days is ready for pitching its contents into the fermenting tuns.

Having familiarized myself with the methods of microscopic examination and preparation of pure cultures adopted by the Berlin Botanical Laboratory, I moved to the “scientific-technical laboratory” of the same institute, which is headed by Prof. Dr. Lange. Here I familiarized myself with the methods adopted by the Institut for investigating grain, bread, malt, products of distillery and brewing production, and yeast, after which I began special work on the influence of oxalic acid on distillery and brewing yeasts. The results of this work were published in Nos. 14 and 15 for 1907 of the journal Wochenschrift für Brauerei, in the article “Zur Wirkung von Oxalsäure auf Brauerei und Presshefe,” and in the Institute’s Jahrbuch for 1908.

Upon completion of the aforesaid work, I moved from the scientific-technical laboratory to the laboratory of Prof. Schönfeld, where I worked on white beer, after which I obtained practical acquaintance with this production at two plants: “Weissbierbrauerei Walff’a” and at the Cr. Stauch plant in Berlin.

The production of Berlin white beer (“Berliner Weissbier”) has in recent years begun to develop very strongly and, apparently, to have a future not only in Germany, but also beyond its borders and even

is desirable, since it gives a light, refreshing drink, and moreover with a comparatively small alcohol content (about 2%). Meanwhile this production is entirely unknown to Russia, which is why I consider it necessary to dwell on it somewhat and give a brief description of it.

The brewing of beer from wheat and barley, which arose in Berlin more than a century ago, gradually developed and has at the present time taken the form of the modern production of Berlin white beer, whose characteristic features are: the use of wheat together with barley, top fermentation, and the joint action of yeasts and lactic-acid bacteria.

For white beer, chiefly dark (braunfarbige Sorten) varieties of wheat are used, which, according to the prevailing opinion of practitioners, are processed considerably more easily and supposedly yield a more strongly foaming beer. For brewing, the chief merit of wheat, as of barley, lies in its starch content—the more of the latter, the fewer protein substances, the quantity of which should not exceed 12%. Wheat with grains of medium size is considered the most suitable. In addition to good germinative capacity and the satisfaction of all requirements common to barley, wheat must also meet the following conditions: the weight of 1,000 grains should be within the limits of 33–48 gr., and the weight of a hectoliter within the limits of 76–86 Kil.

The preparation of brewing wheat malt differs somewhat from the analogous operations for barley malt, in accordance with the peculiarities of wheat, which consist in a very thin husk compared with barley and in a relatively high content of nitrogenous substances.

Accordingly, the steeping time for wheat is shorter—on average 50 hours, and with periodic blowing-in of air even less. Germination is carried out in a thinner layer than for barley, in view of its tendency to overheat, associated with the high content of nitrogenous substances.

The absence of husk, which creates an easy possibility of damage to the sprouts, compels the turning-over to be performed as rarely as possible: during the first 2 days every 8–12 hours, on the 3rd–4th days every 18–22 hours; on the 5th day the malt is sent to wither.

The drying of the malt is usually carried out in a kiln with a double sieve and lasts 24 hours, with a maximum temperature of 62–64°R (measured in the air).

On the upper kiln floor the malt is loaded in a layer thinner than is ordinarily customary. At a gradually increasing temperature, but one that always remains below 35°R., it is dried as far as possible, after which it is transferred to the lower kiln floor.

For Berliner white beer, observance of the indicated requirement concerning temperature is especially important and is strictly maintained, since this determines the light color and delicate taste of the beer obtained; whereas the drying of wheat malt for such types of beer as, for example, Gratzer Bier is conducted quite differently, analogously to the kilning of malt for Munich beer. In this case the malt is transferred from the upper kiln floor to the lower one with a water content of 18–20%, as a result of which caramelization processes occur to a greater degree, determining the characteristic aroma of the malt and its dark color.

Good wheat malt gives an extract, calculated on dry matter, of 78–85%; the weight of one hectoliter of it should range between 62 and 65 kg.

As for hops, their quality must in every case be no lower than that used for bottom-fermented beer, since, owing to the comparatively weak concentrations of white beer and its poverty in alcohol, it is more susceptible to infection than bottom-fermented beer.

The fermentation of white beer is carried out with top yeasts of the Frohberg type, which give a high degree of attenuation. Their distinguishing feature is their ability to form long chains.

The lactic-acid bacterium used in white beer has the form of rods whose length is 5–6 times greater than their width; it differs from the distillery lactic-acid bacterium by a lower temperature optimum, namely 22–30°C instead of 45–50°C.

In mashing, \(3/4\) wheat malt and \(1/4\) barley malt are taken. Each is sent to the crusher separately, since the dimensions of barley and wheat grains differ greatly. Moreover, for the wheat malt the rollers of the crusher are not set too close together, so as, as far as possible, not to destroy the thin, delicate husk of the wheat grains. The latter circumstance is of very great importance, since with \(3/4\) wheat malt a mash is obtained with a very small quantity of filtering material. Therefore, wishing to preserve the husk of the wheat malt, at some plants 1–2 days before mashing it is sprinkled with 2–4% water in order to impart elasticity to the husk. For the reason indicated, filtration of the mash in white beer…

brewing requires great attention and time, extending to more than 5–6 hours.

Hops are added directly into the mash tun in the amount of \(1/2\)–1 kil. per 100 kil. of the malt being mashed.

As for the method of mashing, here too, as in bottom-fermentation brewing, it is far from standardized and is carried out differently at different breweries. In general, mashing lasts \(2^{1/2}\)–\(3^{1/2}\) hours.

Boiling of the mash is in most cases avoided, the temperature being limited to \(62\)–\(64^\circ R\). If boiling is necessary, as for example in summer, then its duration is usually reduced to a minimum, since it is considered that boiling causes a considerable deterioration in the taste of the product.

As an example I cite the method of mashing adopted at “West-Weissbierbrauerei” Wohl’a (Berlin, Zossener Str., 30).

Mashing is carried out at \(40^\circ R\).

For 30 min. the temp. is raised to \(48^\circ\).

”	”	20	”	”	”	\(51^\circ\).
”	”	40	”	”	”	\(55^\circ\).
”	”	60	”	stands	”	at \(55^\circ\).
”	”	30	”	raised	”	to \(62\)–\(64^\circ\).
”	”	10	”	stands	”	at \(64^\circ\).

In summer the mash is brought to boiling.

The mashing adopted by the brewery “Weissbierbrauerei Christ Stauch” (Berlin N. Wildonower Str., 4)

Mashing at \(28^\circ R\).

For \(1^{1/2}\) hours it is raised to \(57^\circ\).

Saccharification is carried out for \(1/2\) hour at \(57^\circ\).

After this, \(1/3\) of the mash is transferred to the lauter tun. To the remaining \(2/3\) hops are added, \(1/2\) kil. per 100 kil. of malt, after which the mash is quickly heated to boiling, which lasts 20 minutes.

The wort is displaced from the spent grains with hot water (\(67^\circ\)–\(70^\circ R\)); the run-off water is 0.5–0.8 Bal.

From the receiver after the lauter tun, the hot wort goes without boiling to the coolers, first open ones (trays, surface coolers, etc.), then closed ones.

The absence of boiling of the wort accounts for the susceptibility of the resulting beer to diseases, since many kinds of organisms capable of developing inevitably enter the filtered wort; for this reason Prof. Schönfeld urgently recommends a brief (15–20

minutes) boiling of the filtered wort in order to sterilize it. In practice, however, this proposal is rejected, since it is found to impair the taste of the beer.

From the refrigerators, at a temperature of 12–15°R in winter and 8–10°R in summer, the wort enters the collecting vat, where yeast is added (1 litre of thick yeast to 5 hectolitres of wort). After 12 hours, part of this wort from the collecting vat goes to be mixed with wort that has already fermented, while the bulk of it is poured into the fermentation vats, where fermentation takes place at 14–19°R and lasts 4–5 days. The fermentation vats, like in general all the vessels of the plant—because of the beer—are not coated with varnish, which suffers from acidic fermenting liquids, but are only carefully washed and coated with milk of lime.

The fermentation of the wort is carried out not by any single pure culture of yeast, but by a mixture of yeast with lactic-acid bacteria.

When yeast and bacteria act jointly, a constant quantitative relation is established between them, changing according to the conditions adopted by the plant and especially according to temperature. This ratio for fresh yeast being pitched ranges within (4 : 1)–(6 : 1).

At the beginning of fermentation the yeast multiplies faster than the lactic-acid bacterium; the latter, however, overtakes it toward the end of fermentation, so that the initial quantitative ratio is restored.

At the beginning of fermentation a dark layer is brought to the surface of the wort, consisting of coagulated proteins, hop resin, and foam. This scum is carefully skimmed off with a scoop 2–3 times. Approximately 2 days after the start of fermentation, the fermenting wort begins to be covered with a loose, white foam with large bubbles, in which the content of lactic-acid bacteria gradually increases, so that by the end of fermentation a dense layer forms on the surface of the liquid, containing about 92%–96% of the total quantity of lactic-acid bacteria in the wort and about 40% of all the yeast, of which about 50% settles to the bottom of the vat.

Thus, by this period the fermenting wort is to a considerable extent freed from the active yeast and bacteria. Before the wort is drawn off, the yeast layer is carefully skimmed off.

The degree of attenuation of the wort in the vats is 66–75%. The gradual change in acidity during fermentation is evident from the following data, showing, in cubic centimetres of normal alkali solution, the acidity of 100 cubic centimetres of fermenting wort at various times of fermentation, counting from the moment the yeast is pitched.

After 4 hours . . 0.2 cubic cent.

“ 18 “ . . 0.3 cubic cent.

“ 66 “ . . 1.4 cubic cent.

“ 90 “ . . 2.0 cubic cent.

The final amount of acid formed depends on the temperature of the working vat, and therefore maintaining the latter at a definite level is very important, since this circumstance determines the known acidity and, together with it, the characteristic taste of the resulting product. The most suitable temperature for fermentation in vats is taken to be 14–19°R. The acidity of white beer ready for consumption, after standing 3–5 weeks in bottles (in a cellar), is usually twice as great as the acidity of beer fermented in vats.

The fermented beer from the fermentation vats is run into a collecting vessel, where it is mixed with wort that has only just been pitched with yeast, or, at most, has stood with it for 8–10 hours. This addition of so-called “young beer” ranges from 1/5 to 1/2 of the amount that has fermented. The resulting mixture of old and young beer is then diluted with 10–35% unboiled tap water, after which, without filtration, it is bottled; in the bottles the beer matures over the course of 2–5 weeks, being kept in a cellar at a temperature of about 7–9°R. During storage the yeast, bacteria, coagulated and precipitated proteins—all this settles to the bottom in a fairly dense layer about 1 cent. thick. During bottling, about 3–5% of the total quantity of yeast and lactic-acid bacteria gets into the bottles; besides these, the sediment of bottled finished beer naturally contains a rather large quantity of all sorts of extraneous organisms, which always enter the beer in greater or lesser quantity as contamination. The latter, as is evident from the description given, are afforded ample scope.

If white beer is sold by the brewery in barrels, then the addition of water is carried out by the purchaser himself—usually by restaurant keepers, who in this case do not spare water, bringing its amount up to 40–45%. In any event, the addition of water in general, and especially such a considerable addition, greatly lowers not only the quality but also the stability of the white beer, diluting its preservative constituents, namely alcohol and lactic acid.

In the case where a large addition of water is to be made, in order to maintain the normal yellow color of the beer, a little roasted malt (“coloring”) is added during mashing, or part of the dark malt is used.

In addition to normal white beer, some factories produce the so-called Malzbier, which differs in that, when it is bottled, instead of the water usually added, a fairly concentrated solution of sugar is added in the amount of 20 Kil. per 100 Kil. of mashed malt, after which the beer in the bottles is pasteurized in order to kill the yeast and bacteria and thereby protect the added sugar from possible fermentation.

Sometimes Märzweissbier is also prepared, distinguished by the greater strength of the fermenting wort (12–16° Bal) and by the absence of added water. Such beer is kept for several months in bottles laid on their side, producing as a result a beverage with an aromatic wine-like taste.

The equipment of white-beer factories is for the most part very primitive. Their size is small, and activity in winter is reduced by half, since white beer sells well only in summer.

The productivity of the factories I inspected does not exceed the processing of 130–260 centners of malt per day. The exceptions are 2–3 white-beer factories with a productivity of up to 150,000 hectoliters annually.

The brief description given notes the most characteristic aspects of the production of white beer, which is one of the prominent representatives of top-fermentation brewing. The latter has recently begun more and more to attract the attention of those who look after this branch of industry, the reason being the desire to make production cheaper; and this condition is met as well as possible by top-fermentation brewing, where, owing to the high fermentation temperature, the enormous costs of cooling are eliminated to a considerable extent, while intensive and rapid fermentation greatly increases the productivity of the brewery.

In addition to laboratory work at the Berlin “Institut für Gärungsgewerbe,” I attended lectures in various special courses given there at different times, such as, for example, a course for brewers, a course for directors and owners of yeast factories, and so on. In the present case, attention was directed to the organization and curricula of these courses, which is of special interest, since, with the establishment at the Tomsk Technological Institute of a distillery laboratory of nutritive substances, similar experimental courses for distillers will also have to be organized.

After the Berlin “Institut für Gärungsgewerbe,” I worked for 5 weeks on fermentation technology at the School of Viticulture and Horticulture in

Geisenheim (“Kön. Lehranstalt für Obst-Wein— und Gartenbau,” Geisenheim am Rhein).

The said school is maintained with funds from German winegrowers and gardeners and is subsidized by the Prussian government. The training of practical workers for viticulture and horticulture is the task of this institution; in addition, it is charged with resolving all sorts of practical difficulties and directing the latter.

Alongside the multiyear permanent courses, the school organizes periodically repeated short courses for practical workers in viticulture and horticulture of every possible level. The staff consists of the school director, Prof. Wortmann, and 10–15 members of the teaching personnel. In the “Pflanzen-Physiologisches Laboratorium” of this school, under the direction of Dr. Kroemer, I became acquainted with various types of wine yeasts, with the conditions of fermentation in winemaking, and with the influence of various factors on the course of the latter. After this I attended a two-week course in fruit winemaking with practical work and inspected several wine cellars and sparkling-wine factories. The school has a station of pure cultures of German wine yeasts, founded and directed by Prof. Wortmann.

All work in the laboratory of the station is conducted by Prof. Wortmann’s assistant, Ms. Zeiss.

Besides preparing for sale and cultivating various races of yeast suitable for practice, the station carries out purely scientific investigations into fermentation phenomena, the work of various races of yeast and other organisms whose participation is inevitable at various stages of the fermentation of grape must. The results obtained by the station are transferred into practice, and practice in turn communicates its observations to the station.

During the busy period of winemaking (October and November), the station receives up to 3–4000 orders for yeast annually; for this reason a large supply of pure yeasts is prepared in advance for that time, usually dispatched in quarter-size champagne bottles. If the shipment is intended for abroad and involves a long journey, the pure cultures are sent on cotton wool in Freudenreich flasks. The stock cultures are preserved in a 10% sucrose solution in Freudenreich flasks, from which, when transferred, the yeasts are refreshed by double fermentation.

A collection of frequently needed yeasts is usually kept in test tubes with a cotton stopper, in wort. If an inoculation is made from such a test tube, then first of all the culture is transferred into a new test tube, which is then kept in reserve.

Fermentation is conducted on natural grape must or on concentrated Sicilian must, which is diluted with water (1 to 4), boiled, clarified with egg white (one egg white per 10 liters of must), filtered, and sterilized for 1/2 hour in bottles closed with cotton stoppers, which in turn are tied over with moistened parchment paper.

In its methods of scientific investigation, the station described is close to the Danish school. Hansen’s methods for obtaining pure cultures, work with inoculation cabinets, and the use of Freudenreich flasks—all this has been adopted and is strictly observed by the said station.

Having finished the description of my work on zymotechnology, I turn to the laboratory of Prof. K. Lintner at the Munich Polytechnic, where I spent one summer semester.

The said laboratory was of twofold interest: first, as a laboratory analogous to the laboratory of nutritive substances of the Tomsk Technological Institute; second, as one situated in Bavaria, famous for its beer, and moreover standing close to practice thanks to its connection with the Munich experimental station of brewers (“Wissenschaftliche Versuchsstation für Brauerei,” Munich, Ohlmüller Str. No. 42), whose director is likewise Prof. K. Lintner.

Prof. Lintner’s laboratory, apart from several auditors who are here permanently, is usually filled with students from the local University and Polytechnic. One part is engaged in diploma work; another is taking the established course of investigations and analyses in food technology, which usually occupies at least the whole winter semester of the worker.

This course consists of analyses of raw materials, intermediate and final products of production in the techniques of fermentation and sugar manufacture.

Among the methods of investigation adopted by Prof. Lintner’s laboratory and by the experimental station of the Munich brewers, mention should be made of the polarimetric determination of starch and the refractometric determination of extract and alcohol in beer.

The complexity and duration of the methods of determining starch that have been used up to now are to a considerable extent eliminated by the below-described—

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...by the polarimetric method of Prof. Lintner, and in accuracy the latter, in any case, is not inferior to the former.

This entire method is based on the fact that starch in the soluble state possesses a high and quite definite optical power; thus, by determining the angle of rotation of a known weighed amount of a substance whose starch has been converted into the soluble state, one can, on the basis of the formula giving the specific rotation, calculate the starch content in the substance being analyzed. The observed angle of rotation is, of course, also influenced by certain other substances of the starchy material under investigation, for example, protein substances and the products of their decomposition.

In the majority of cases this influence, already from the quantitative relation between starch and foreign substances, cannot be great; moreover, this factor is to a considerable extent eliminated by the addition of a solution of phosphotungstic acid, which converts most of the aforementioned substances into a precipitate removable by filtration.

After a number of modifications, the polarimetric method for determining starch was developed in the following form, adopted by the experimental station of the Munich brewers:

2.5 g of a finely ground and air-dry substance are mixed in a mortar with 10 cc of distilled water into a homogeneous thick paste. To this, with stirring, 20 cc of sulfuric acid of specific gravity 1.70 are added. The resulting solution, after 10–15, at most 25 minutes, is quantitatively transferred into a 100 cc volumetric flask. For washing the pestle and mortar, sulfuric acid of specific gravity 1.30 is used. After the addition of 5 cc of a solution (8%) of phosphotungstic acid, the flask is filled to the mark with sulfuric acid of specific gravity 1.30, thoroughly shaken, and filtered through a folded filter; at the end of the funnel a small smooth filter is placed beforehand, preventing accidental rupture of the folded filter. After 20–30 cc of the initially slightly turbid filtrate has been filtered, without returning the last to the funnel for refiltration, the further filtrate is collected in a new dry Erlenmeyer flask, from which the liquid is poured into a polarization tube 20 cm long and polarized in the sodium light of an Auer burner.

The specific rotation of soluble starch under the conditions of the experiment with sulfuric acid*) is taken as equal to 191°,7. For determining

) With hydrochloric acid, 202°—see Zeitschr. für Untersuchung der Nahrungs und Genussmittel, sowie der Gebrauchsgegenstände*. 1907, 13–14; Heft 3.

For the starch content, the formula used is

\[ C=\frac{100\cdot L}{l\cdot[\alpha]^{20}_{D}}, \]

where \(L\) is the angle of rotation observed in the polarimeter,

\(l\) is the length of the polarization tube in decimeters,

\([\alpha]^{20}_{D}\) is the specific rotation of soluble starch, taken in the present case as equal to \(191^\circ.7\),

\(C\) is the starch content in grams per 100 cc of the polarized solution.

Since the weighed portion was taken at 2.5 gr., therefore, multiplying \(C\) by 40, we obtain the number indicating, in percent, the starch content in the substance investigated, in the present case in the air-dry substance.

As the annual practice of the experimental station of the Munich brewers has shown, the polarization method usually gives, for the starch content, figures lower by \(4 \div 6\%\) than those obtained by the previously adopted methods connected with inversion. This latter circumstance is explained by the fact that in the polarization method pentosans are excluded, whereas under the former methods, connected with inversion, they were also included in the account of the starch being determined, thereby, of course, increasing the resulting percentage content of the latter.

In order not to resort each time to calculation by the formula given above, Table No. 1 has been compiled, giving, from the observed angle of rotation during polarization, directly the starch content in the air-dry substance investigated.

Besides the method described, among the methods of investigation employed by Prof. Lintner’s laboratory and by the experimental station of the Munich brewers, attention should also be paid to the refractometric determination of alcohol and extract in beer. This determination is carried out with the aid of the immersion refractometer (Eintauch–Refraktometer) of Carl Zeiss.

The principle on which this instrument is constructed is based on the fact that a ray of light, passing from one medium into another, undergoes a certain refraction dependent on the properties of the medium. In the case where one medium (the prism of the apparatus) remains constant, while the other (the solution of the substance under investigation) changes, certain fluctuations can be observed in the degree of refraction of light, connected with the change in the medium under investigation. Consequently, having to do with a definite substance and knowing the dependence between the various concentrations of its solutions on the one hand and refrac—

Table No. 1.

Specific gravity	% starch in an aqueous solution	Specific gravity	% starch in an aqueous solution	Specific gravity	% starch in an aqueous solution	Specific gravity	% starch in an aqueous solution
4.70	49.04	4.89	51.02	5.08	53.00	5.27	54.98
4.71	49.14	4.90	51.12	5.09	53.10	5.28	55.08
4.72	49.24	4.91	51.23	5.10	53.21	5.29	55.19
4.73	49.35	4.92	51.33	5.11	53.31	5.30	55.29
4.74	49.45	4.93	51.44	5.12	53.42	5.31	55.40
4.75	49.56	4.94	51.54	5.13	53.52	5.32	55.50
4.76	49.66	4.95	51.64	5.14	53.62	5.33	55.61
4.77	49.76	4.96	51.75	5.15	53.73	5.34	55.71
4.78	49.87	4.97	51.85	5.16	53.83	5.35	55.82
4.79	49.97	4.98	51.96	5.17	53.94	5.36	55.92
4.80	50.08	4.99	52.06	5.18	54.04	5.37	56.03
4.81	50.18	5.00	52.16	5.19	54.15	5.38	56.13
4.82	50.29	5.01	52.27	5.20	54.25	5.39	56.24
4.83	50.39	5.02	52.37	5.21	54.36	5.40	56.34
4.84	50.50	5.03	52.48	5.22	54.46	5.41	56.45
4.85	50.60	5.04	52.58	5.23	54.56	5.42	56.55
4.86	50.71	5.05	52.69	5.24	54.67	5.43	56.66
4.87	50.81	5.06	52.79	5.25	54.77	5.44	56.76
4.88	50.91	5.07	52.89	5.26	54.88

…of the ability of these solutions with another, it is possible, judging by the degree of refraction of light, to determine the content of the given substance in the liquids under investigation.

Thus, the refractometer provides a simple, rapid, and in some cases extremely accurate analytical method.

When one is dealing with perfectly pure chemical solutions of one substance or another, refractometric determination gives results that apparently surpass in accuracy all methods known up to the present time.

Very good, mutually comparable results are also obtained when dealing with impure solutions of the substance under investigation, but with a more or less constant composition as regards extraneous substances that are not the object of the given refractometric study.

Very inaccurate and scarcely comparable data are obtained if the liquids under investigation differ greatly in the content not only of the substance directly being studied in them, but also of all the other substances dissolved in them.

The possibility of investigating a liquid refractometrically in the thinnest layer and in a quantity not exceeding a drop constitutes a great advantage of this method and makes it possible to apply it to liquids of the darkest coloration, which are completely inaccessible to such instruments as, for example, the polarimeter. Simplicity, speed, and accuracy with perfectly pure substances place refractometric determination very high. But in the case where a mixture of various substances is investigated and, moreover, some optically active body is being determined—for example, sugar—then undoubtedly preference must be given to the polarimeter over the refractometer, since there are, in nature, comparatively very few optically active bodies capable of influencing the readings of the polarimeter, whereas the readings of the refractometer are influenced, to a greater or lesser degree, by all substances without exception.

In addition to what has been indicated, temperature also has a very great influence on refractometric readings; therefore maintaining it, during the investigation, at a known level is a very important circumstance and is achieved by the use of water cooling specially designed for this purpose, both for the working part of the apparatus itself and for the liquid being investigated.

In addition to studying the methods adopted by the Fermentation-Technical Laboratory of the Munich Polytechnic and the experimental station of the Munich brewers, during my stay there I also began special work on the question of mashing in brewing.

The process of preparing the mash, despite being one of the fundamental processes of brewing, is to this day an operation that has been studied extremely poorly and therefore, in most cases, is very little controlled, or, more precisely, almost not consciously controlled at all.

The absence of strictly developed scientific foundations in this area is evident from the fact that, both among us in Russia and everywhere abroad, mashing is conducted in endlessly varied varia—

...in operations, often with the use of so-called secret methods, zealously guarded by their authors. Of course, in large breweries that have worked for years with malt of approximately the same quality, there are such mashing masters who have grasped, for their own malt, so to speak, the secret of mashing and conduct it in a strictly defined direction desirable for the given case.

But even in this case the secret of mashing remains truly a secret not only for the uninitiated, but also for its author—the specialist mashing master—who, knowing the corresponding method of mashing for his malt, still cannot say why this method can be applied especially successfully in the given case. The theoretical side remains, to this day, far from developed, and therefore in practice people usually proceed by touch, with their eyes closed.

One of the questions that arises here in the first place is the question of how to conduct the mashing of one and the same malt in order to obtain wort that in one case is weakly fermentable, for beer of the Munich type, and in another case strongly fermentable—for beer of the Pilsner type.

This was taken as the subject of my work here.

The greater or lesser fermentability of the wort, independently of the properties of the yeast used, is determined by the ratio of the quantities of maltose and dextrins contained in it: the more maltose and the fewer dextrins, the more easily the wort ferments and the higher the degree of fermentation of the beer obtained thereby. Under the opposite conditions, a lower degree of fermentation is obtained.

Thus, one of the first questions connected with the indicated subject is to determine the conditions for the formation of different quantities of maltose and dextrins in the wort, depending on changes in the methods of mashing.

The principal factors in the mashing process in brewing are the temperature and the quantitative ratio of water and malt taken for mashing. Therefore, having settled on the indicated subject, I set myself the task first of all of tracing the influence on the quality of the wort obtained: first, of different mashing temperatures; second, of different quantitative ratios of water and malt taken for mashing.

Since the subject was chosen with factory practice in mind, the variations in the ratio of the quantities of water and malt in the experiments therefore remained within the limits from \((1 : 4)\) to \((1 : 2)\).

In the wort thus obtained, determinations were made of: specific gravity (pycnometrically), extract, maltose, non-sugar, and, in addition, the wort was tested for the degree of fermentation. The latter determination was carried out as follows: for 200 cc of wort, 5 g of fresh yeast from the Munich brewery Löwenbräu were taken. The wort with yeast was poured into a 500-cc apothecary bottle, closed with a cork fitted with Gaiduk’s water seal. The bottle was placed in a water bath heated to 25–27°C. Fermentation continued for 72 hours, after which the degree of fermentation was determined in the resulting beer (the specific gravity was determined pycnometrically).

The short interval of the summer semester which I devoted to work in the named laboratory made it possible to carry out, according to the planned program, only a few dozen experiments with one light and one dark variety of Munich malt.

Of course, this is far from sufficient for a correct and complete elucidation of the subject taken up; for that reason this work could not, within the indicated time, assume a finished form. Therefore, without citing the entirety of the numerical material obtained, I shall confine myself here to several conclusions drawn from it, which already apparently clarify certain aspects of the question touched upon. At the same time, I must, of course, emphasize that the conclusions presented below are made only within the limits of the experimental data obtained, from experiments carried out in insufficient number; as a result, it is possible that with a broader program of these experiments, which I intend in the near future to extend to many diverse varieties of malt, the conclusions given here may change somewhat, while for the time being the available results give the following:

1) The yields of extract fluctuate to an extremely slight degree depending on various variations in the methods of mashing with respect to the gradualness and rapidity of changes in the temperature of the mash, provided that the latter does not exceed 70°C, and provided that the mashing itself lasts 2–3 hours.

2) The yield of extract rises by 3–5% in comparison with the normal case if, after carrying out the mashing at room temperature, the mash is left before the subsequent usual mashing operations for 12 or more hours at 15–20°C.

3) With a decrease in the ratio of the quantity of malt to the water taken for mashing, the ratio of maltose to non-sugar in the resulting wort increases.

Regarding any regularity in the changes in the degree of attenuation of wort obtained in various ways, it is difficult, on the basis of the available material, to draw any definite conclusion.

The latter circumstance depended to a considerable extent on the impossibility of properly and uniformly monitoring the test of the wort for the degree of attenuation, since under the conditions of the accepted work schedule in the laboratory, followed without deviation, the 72-hour fermentation period in most cases could not be maintained; thus in some samples fermentation continued for 2 days, in others for 3, and in still others for 4–5 days, which, of course, yielded results that were not very comparable and therefore did not illuminate the question under consideration sufficiently clearly.

In addition to work in Prof. Lintner’s laboratory, I inspected many Munich breweries: Löwenbräu, Pschor, and others; among them I shall dwell briefly on the upper-fermented beer brewery of Mr. Schramm.

The capacity of the brewery is about 10,000 hectoliters; it operates on wheat malt with an addition of 10–15% barley malt.

Mashing is carried out with double boiling. The filtered wort is then boiled with hops. The wort is obtained at 10–12 Balling. Fermentation in vats lasts 60–70 hours at a temperature of about 18–20°R. After this the beer, without dilution with water and filtration, is bottled; the bottles are placed in a cellar at a temperature of 8–10°R, where they remain for 2–3 weeks, after which they are put on sale. The degree of attenuation is about 70°. In the finished beer the yeast settles to the bottom as a thick, dense sediment. With careful uncorking and pouring, the beer is entirely free of turbidity, with a beautiful golden color. The taste of the upper-fermented Munich beer is not very characteristic, and it has little expression, so that it is drunk with a small piece of lemon placed in the glass.

Besides the breweries, the experimental station of the Munich brewers, “Wissenschaftliche Station für Brauerei,” Munich, Ohlmüller Str., No. 42, and the “Akademie für Brauerei,” as well as the “Versuchs und Lehr-Brennerei” at the railway station Freising, 1–2 hours’ journey from Munich, at the higher agricultural school in Weihenstephan, were also inspected here.

The experimental station of the Munich brewers, like most similar institutions in Germany, is the result of private initiative—in this case, of Prof. K. Lintner (the father). It was founded in 1876. Both according to the founder’s idea and in actuality, its purpose consists in serving the tasks of brewing. Outstanding

... among the figures who had made the station widely known were Prof. K. Lintner (the father), Reischauer, Aubry, and Will. The station is supported chiefly by funds from the union of Munich brewers, which, unlike the Berlin one, consists almost exclusively of the owners of large breweries, both Bavarian and foreign.

At the head of the entire laboratory at present stands Prof. Lintner (the son), who also directly supervises its chemical division; the physiological division of the laboratory is directed by Prof. Dr. Will.

In addition to chemical and biological analyses, supervision of production at the member breweries, scientific work, and partly educational-pedagogical activity, the station is also engaged in the preparation and sale of pure yeast cultures. There is a special department with apparatus for obtaining pure-culture yeast on a large scale, but the apparatus here has not been in operation for several years; and when selling pure-culture yeast they either send it in test tubes, or proceed as follows: they take the yeast in the required quantity directly from the Munich brewery for whose yeast there is an order. These yeasts are inspected at the station and, if the result of the examination is satisfactory, are sent directly to their destination in the necessary quantity, in pressed form.

As for the brewing academy and the school of distilling in Weihenstephan, I shall not dwell on these institutions at length, since in their aims, tasks, and partly in their organization they are to a considerable extent analogous to the Berlin “Institut für Gärungsgewerbe,” with the difference that the scale taken here is considerably smaller, and this enterprise is governmental rather than private, with tasks chiefly pedagogical. Its directors and leading figures are the following persons: Prof. Vogel—director of the academy, Kraudauer, Ganzenmüller, Bücheler, Bleisch, and others. Attached to the academy are experimental brewing and distilling plants.

In order to conclude the description of my studies in fermentation technology during my trip abroad, I shall add a few words about the Pasteur Institute (Institut Pasteur, Paris, Rue Dutot). This institute pursues very broad and extremely varied aims, serving chiefly the needs of medicine. It arose from private donations and at present represents an enormous institution, occupying an area of 14,600 square meters, with numerous spacious buildings situated upon it.

In one of the buildings is Pasteur’s former apartment; his wife and children now live there, and below there is a richly finished mosaic crypt, where Pasteur’s remains repose. The Institute has at its disposal a very extensive library, accessible for the use of all who wish to consult it. In all the other buildings are housed the various departments and laboratories of the Institute, among which I stopped at the Fermentation Service (Service des fermentations), under the direction of M. Bertrand and belonging to the department of “Higher Studies” (Laboratoire des Hautes Études). The director of the latter is Duclaux. In the fermentation laboratory, on the one hand, purely scientific investigations connected with questions of fermentation technology are conducted; on the other hand, purely pedagogical aims are also pursued here.

On the upper floor of this building there is a teaching laboratory for 20 places. Here students are trained both in chemistry and in zymotechnology for various branches of fermentation technology. Attached to the laboratory are miniature apparatuses for various industries of fermentation technology, enabling students to carry out, on a small scale, certain factory processes. On the lower floor there are rooms for carrying out analyses and tests in response to inquiries coming from practice.

So far as I could judge from my personal impression and on the basis of what I heard from various persons, this department of the Pasteur Institute does not stand very high and therefore does not enjoy great popularity.

After completing my studies in fermentation technology, I spent the summer semester in the organic laboratory of Prof. Wohl (Danzig-Langfuhr, Polytechnikum), where I worked on the question of resolving and obtaining optically active isomers of glyceric aldehyde.

This work, during the indicated interval of time, was not brought to any definite conclusion; nor did it seem possible to spend another winter semester, out of the time of my assignment, on the same subject in this laboratory, since I still had to work, in addition, on sugar production, for which purpose I moved to the “Institut für Deutsche Zucker-Industrie” in Berlin.

The said institute belongs to the union of German sugar manufacturers. Its purpose, like that of all similar institutions, is the guidance and improvement of the corresponding branch of industry—in the present case, sugar production. Since 1903, “In

The Institut für Deutsche Zucker-Industrie is housed in a specially constructed, richly furnished building (Amruner Str. 65—Berlin N).

In accordance with the tasks it pursues, the institute is divided into an educational, an analytical, and a scientific-experimental department.

The educational department occupies the second floor, where there are an auditorium, two laboratories: a large one—for 40 places—and a small one for the women’s course, with 27 places; and a polarization room with artificial cooling and heating to maintain a constant temperature in this room.

The weighing room, library, and other small departments related to the laboratories are located on the same floor.

At each working place in the laboratory there are: gas, water, a pipeline for compressed air, and electrical energy in the form of a current of 220 volts.

On the second floor there are also a physics room, an office, and the director’s study. On the lower floor are located a grinder, beet slicers, presses, and graters of various designs. All are set in motion by electricity. Here too there is a small laboratory for carrying out beet analysis.

The upper floor is occupied by a museum and a laboratory intended for tests and all sorts of analyses, which constantly arrive at the institute in enormous quantity, so that this department is served by a special staff of four assistants.

At the head of the entire institute stands Prof. Herzfeld. The teaching laboratories are directed by Dr. F. Ehrlich, in addition to whom there are three more instructors.

During the summer semester the teaching staff is occupied with pedagogical work, while during the rest of the year it works under the direction of Prof. Herzfeld on various specialized topics, since during the winter semester no courses are taught, and all the institute’s free forces are directed toward solving both scientific, purely theoretical, and various technical questions connected with the practice of the sugar industry.

On the advice of Prof. Herzfeld, I chose the winter semester for my work here. At first I familiarized myself with the research methods adopted by the institute, which I shall not describe here, since this is of only programmatic interest. After that I proceeded to special work on the influence of glutamine on the polarimetric determinations of sugar in beet.

Since glutamine, by its structural formula, is possible in two optical isomers, and it is unknown in the form of which—

Since it is rarely found in beet, therefore in studying the question outlined for us it seemed necessary to obtain glutamine directly from beet.

From the works of Schulze, Boschard, and Sellier it is known that the content of this substance in beet varies, beginning with 1 gr. per 1 lit. of expressed beet juice and ending with the very smallest quantities, while obtaining it is associated with great difficulties and does not always give satisfactory results.

Thus, when these experiments were repeated in 1906–7 at the Berlin institute, from 60–70 lit. of juice there was obtained, instead of glutamine, a thick, dark mass which solidified with time without crystallization. Therefore, the repetition of the experiments for obtaining glutamine was of interest already in itself. After a whole series of changes it was carried out with positive results in the following manner.

To the pressed juice of sugar beet there is added, until then, a neutral solution of lead acetate, until a further addition of it to the filtrate of a separately taken sample no longer causes further precipitation. After this the liquid is shaken and filtered under suction through a large Büchner filter. Further, to the filtrate there is added a solution of mercuric nitrate, strictly avoiding an excess of the latter, since an excess of this reagent partly dissolves the precipitate originally obtained.

Thereafter neutralization with sodium carbonate is carried out to a weakly alkaline reaction, after which, by repeated decantation of the precipitate from it, the sugar is removed down to the last traces, i.e., until \(\alpha\)-naphthol in the water decanted from the precipitate gives not the slightest characteristic coloration.

The precipitate of mercury compounds washed in this way is decomposed in portions with freshly prepared ammonium sulfide. For this purpose, after pouring off the excess liquid from the precipitate, it is shaken vigorously with the remaining water for its uniform distribution, and after this 100 cc. of the liquid with the suspended precipitate is taken, which is titrated with freshly prepared ammonium sulfide for the decomposition of the mercury compounds. After 2–3 repetitions of titration of separate samples in this way, the necessary amount of ammonium sulfide, without the slightest excess, is accurately established. Then the decomposition of the precipitate is conducted as follows: into a bottle of 1-liter capacity there is taken a definite volume of the previously vigorously shaken washed precipitate, to which is added the necessary amount, determined by titration, of freshly prepared ammonium sulfide. The bottle is tightly closed with a stopper and placed for 1/4 hou-

...into the shaking apparatus. The precipitate of cerium compounds obtained in this way is filtered off and washed, while the filtrate, together with the wash waters, is evaporated almost to the complete removal of ammonia and is again precipitated by the already described method with mercuric nitrate; it is then neutralized with sodium carbonate to a weakly alkaline reaction, washed, decomposed with a fresh solution of ammonium sulfide, after which the filtrate is evaporated as rapidly as possible in broad, flat dishes on water baths, the reaction of the liquid being invariably kept weakly alkaline by the addition, from time to time, of ammonia. When the volume of the liquid has diminished considerably, it is decolorized with animal charcoal, after which further evaporation is continued, at first on a boiling water bath, and finally in a desiccator over sulfuric acid under reduced pressure. Under these conditions glutamine crystallizes without difficulty in white, dull crystals of characteristic form. The preparation is purified by recrystallization. Its yields fluctuate around 0.10–0.15 gr. per 1 liter of pressed beet juice. It should be noted here that only with double precipitation by mercuric nitrate was it possible to obtain glutamine, whereas by the previously adopted method and with a single precipitation by mercuric nitrate only thick crystallizing syrups were obtained, solidifying into a hard amorphous mass of dark color.

In the manner described, three preparations were obtained with optical rotation:

\[ \begin{aligned} \mathrm{A})\quad [\alpha]^{20}_{\mathrm{D}} &= +1.09^\circ,\\ \mathrm{B})\quad [\alpha]^{20}_{\mathrm{D}} &= +1.64^\circ,\\ \mathrm{C})\quad [\alpha]^{20}_{\mathrm{D}} &= +0.98^\circ. \end{aligned} \]

Judging from the data presented, one may think that glutamine cannot have a great influence on the results of polarimetric determinations of sugar in beets: on the one hand because of its comparatively insignificant content, and on the other because of the weakness of its optical rotation.

This question, of course, requires further clarification, since the optical rotation of glutamine preparations obtained in individual cases by different investigators varies very greatly, as is evident from a comparison of the known, and still very few, literature data on this subject.

Nevertheless, in the present case I had to leave the further study of the proposed topic aside, owing to the fact that the method described...

obtaining glutamine could be established only toward the end of December; and since the Christmas holidays that had begun postponed the continuation of my work until January, i.e., to a time when sugar beet already begins to spoil badly, with almost all of its glutamine passing into glutamic acid.

Not having the opportunity to continue the investigation of glutamine as such, I turned to the study of the role played in sugar manufacture by the product of the decomposition of glutamine, i.e., glutamic acid.

Although the glutamine content in beet is comparatively very small, nevertheless the relative amount of glutamic acid in some products of sugar manufacture, and especially in the lower ones, is very high: thus, according to Andrlik’s investigations, the content of glutamic acid in ordinary molasses reaches 3%, and in desugared molasses rises to 8%.

Thus glutamic acid in this respect approaches betaine, whose content in molasses is about 6–7%, and in desugared molasses 16–17%.

It therefore appears that glutamic acid, on a par with betaine, is an invariable companion of the crystallization of sugar; and since it is known that the substances present in this process rarely remain indifferent to it, the question naturally arises of the role of the aforementioned substances in the present case.

This question was also taken as the subject of my next investigation, the results of which were published in the article “Zur Frage der Melassebildung,” included in the Polish volume for 1908 of the journal “Zeitschrift des Vereins der Deutschen Zucker-Industrie.”

Among the sugar factories inspected, I shall note the German factory at Stendal, operating by the pressing method under Steffen’s patent, which he named “Brühverfahren,” i.e., the “boiling method.” The latter is at present only beginning to spread in Germany, and in Russia is almost unknown.

The distinctive feature of this method consists in the fact that the juice from beet cossettes is extracted not by diffusion but by pressing; moreover, the beet cossettes from the slicer first enter hot beet juice obtained earlier, whence after 3–5 minutes they are transferred to a system of presses, by the action of which beet juice is obtained, subsequently treated in the usual manner on

saturation and subsequent stages of the sugar factory. The pressed beet pulp goes to a special dryer.

In the inventor’s opinion, the indicated method has, among other things, the advantage over diffusion that the juices obtained thereby are considerably purer than diffusion juices. The reason for this supposedly lies in the fact that, in diffusion, the washing out of the sugar from the pulp lasts a total of 1–1½ hours, while the diffusion juice, in addition to sugar, is enriched with a considerable quantity of both organic and inorganic compounds passing into it from the beet.

Meanwhile, this negative phenomenon, even if it does occur in the “Brühverfahren,” does so only to a very limited extent, since the interval of time during which the beet remains in a liquid at a temperature close to the boiling point is reduced here to 3–5 minutes.

The corresponding equipment of a sugar factory according to this patent of Steffen can be seen from the appended drawing.

From a beet slicer (a) of ordinary construction, but with flat knives, beet pulp 1–1½ mm thick passes through a funnel (b) into a closed pipe (c) about 35 cm in diameter. From there the pulp is carried along by hot circulating beet juice and is directed into the boiling vessel [A] (Brührog). The latter consists of three parts.

The first (I) is a closed, horizontally arranged cylinder with an auger-mixer. In this part the vessel is equipped with a steam pipe for heating and has a pipe system with hot and cold water.

At the end of this cylinder, beet pulp together with hot beet juice comes from the pipe (c). The mixer located in the cylinder stirs its contents and gradually advances the pulp entering here toward the second part (II) of the boiling vessel. The latter is a continuation of the aforementioned cylinder (I), which here is made perforated and is placed, like the third part, in a closed iron casing with a trough-shaped bottom having an incline toward the middle. Thanks to the openings in the cylinder, the juice here is partially separated from the pulp and flows into the casing, and from there goes further into the pipe (e).

The beet pulp itself, following the motion of the horizontal auger, gradually moves forward and is transferred to the third part of the boiling vessel III—to an inclined auger, arranged

Diagram of the arrangement of apparatuses in a beet-sugar factory equipped according to Steffen’s patent (Brühverfahren).

at an angle of \(25—30^\circ\), and also rotating in a mesh cylinder placed as a continuation of the casing of the second part of the diffusion battery. The purpose of this third part is a further, more complete separation of the juice from the shavings.

From the inclined screw the shavings pass onto a metal cone (d), positioned with its apex toward the screw. By the action of this cone the shavings are pressed out to a certain degree, so that it acts as a kind of preliminary press. After the cone (d), the shavings pass to the next inclined screw (B), whose purpose is to loosen the pressed shavings and to impart homogeneity to them throughout the mass, thereby preparing them for the action of the subsequent extremely powerful vertical presses, of which there are usually several (4–6). Onto these presses (D) the shavings fall from a distributing trough with a screw (i), into which they drop directly from the last inclined screw (B). The pressed shavings leave the vertical presses with a content of about 30–33% dry matter and 9–12% sugar. From there, by a system of belt conveyors, they are transferred to the dryer.

The construction of the latter may in general be very varied; in the case under consideration, however, a Büttner Meyer system dryer was installed, designed especially for beet shavings.

The dried shavings pass through a cooling drum, through which cold air is drawn. The dust separated in this process is deposited in a special trap by steam admitted there. The dry shavings, after passing over automatic scales, are directed to a storehouse, where they lie in a thick layer several meters deep.

The beet juice, separated from the shavings in the second and third parts of the diffusion battery, is directed through pipe (e), through a sand trap (L) and regulator (R), into a receiver (S), into which also enters the juice coming from the vertical presses. The latter passes a foam remover (P) and a trap (M) for retaining pulp carried along by the juice.

The foam remover consists of an upright cylinder with a steam line and a perforated tube for water, arranged somewhat above the level of the liquid. By the action of steam and of jets of hot water injected under pressure through the perforated pipe—usually wash water from the filter presses—the foam, which is released here from the juice in very large quantities, is destroyed.

The pulp separated from the juice by the trap \((M_1)\) is conveyed by a pump \((N_1)\) back to the press (D).

From the collector the juice is delivered by a pump (N₂) to the distributor (r), by means of which this juice is divided into 2 parts in a known proportion, depending on the setting of the regulator. In this arrangement, one part of the juice, bypassing the second pulp trap (M₂), is directed to ordinary saturation; the other part, after first passing through the heater (T), goes to the boiling vessel. The heater is tubular, rapid-acting, with a heating surface of somewhat more than 200 sq. meters; it consists of 4 elements, of which the first 3 are heated by exhaust steam, and the last by live steam.

The pipe carrying the juice from the heater to the boiling vessel has a branch, through which the excess amount of juice taken is directed back to the distributor.

The quantity of beet juice returning to the boiling vessel is approximately 6–7 times greater than the quantity of beet cossettes entering there during the same time. The temperature of the juice after passing through the heater is about 92–97°C; when it is mixed with the beet cossettes, the temperature falls. The contents of the boiling vessel are usually heated to 82–85°C.

The entire passage of the beet between the moment it enters with the cossettes and its exit after the presses lasts about 10 minutes.

With a daily processing of approximately 20,000 centners, setting all the apparatus of the press process in motion requires a machine of about 150 horsepower.

At the start of work, in the absence of beet juice, all the corresponding machines are filled with hot water and are thus put into operation.

In order to give an idea of the utilization of the sugar of the beets processed by the press method described, and in order to compare the results obtained thereby with the results of ordinary diffusion work, Table No. 2 is given below. It has been compiled on the basis of numerical data taken from the report of the meetings of February 1 and 19, 1907, of the commission of the “Berlin Institute of the Sugar Industry” on the comparative testing of Steffen’s press method (Brühverfahren) with the ordinary diffusion method, carried out at the Elsdorf sugar factory (in Germany).

In the data given below, the undetermined losses in the filter-press mud are taken, for Steffen’s method, as equal to those found in this case for the diffusion method.

Table No. 2

Sugar, as a percentage of its content in beets:

Item	By the diffusion method	By Steffen’s method
Passes into the thick syrup	95.08%	84.72%
Losses in the press-mud filter + undetermined losses	1.85%	1.85%
Losses in the diffusion water	0.52%	—
Remains in the processed beet cossettes	2.55%	13.43%

Thus, with Steffen’s pressing method, 10.36% less sugar passes into the thick syrup than with the diffusion method.

As for the greater or lesser profitability of the method described, this, of course, depends in each particular case on the existing prices for fodder and sugar.

An analysis of the pressed, dried beet cossettes obtained by the pressing method, carried out by the Berlin Institute of the Sugar Industry, gives the following figures, placed in Table No. 3.

Table No. 3

Content	Substance
27.78%	sugar
39.17%	non-sugar nitrogen-free substances
7.56%	proteins
0.71%	fat
12.80%	fiber
3.69%	ash
8.29%	water

The yield of such dry pressed beet cossettes is 9.5–10.5%, calculated on the weight of all processed beets.

The figures of the analysis given indicate the high feeding value of this product; moreover Prof. Dr. Lehmann (head of the Zootechnical Institute at the Berlin Higher Agricultural School) comes to the conclusion that the feeding value of the substance under consideration is only 10% lower than that of the very best feedingstuffs.

The market value of such cossettes in Germany fluctuates around 4–5 marks per centner.

The advantages of the described Steffen method, as compared with the diffusion method, are the following:

1) A comparatively very small requirement for water.

2) The absence of costly devices for purifying and removing unsuitable diffusion waters.

3) A reduction in the quantity of juices and, consequently, a reduction in fuel expenses during evaporation.

4) A reduction in the service personnel corresponding to cutting and diffusion, since the flat knives used in this case require considerably less time and labor than ordinary knives, and since the maintenance of the boiling kettle with the entire system of presses requires at most 3 persons.

5) An improvement in the quality of the juices processed.

The expenditure of energy for operating all the apparatuses, and especially the vertical presses, is very great.

Among the various kinds of institutions connected with the sugar industry, I also inspected the “Schule für Zucker-Industrie” in Braunschweig and the beet-sugar selection station of the owners Rabethge-Giesecke in Kleinwanzleben (Rübenzucht in Kleinwanzleben).

The Braunschweig school is a rather old private enterprise, modeled on the Berlin Institute of the Sugar Industry, only of considerably smaller size and, moreover, with chiefly educational aims; in addition, the laboratory is constantly occupied with all kinds of chemical analyses, which bring it greater earnings. The director of the school is Prof. Frühling. The character of the student body of this school is extremely varied: here one may meet people completely unprepared either theoretically or practically, experienced practitioners who have spent many factory campaigns, and, finally, university graduates. Just as the preparation of the students is varied, so too are their ages and nationalities. In the majority of cases all these are persons seeking practical activity, and one of the attractive aspects of this school is the possibility of easily obtaining, upon completion of the course, a recommendation and a position. There are no entrance examinations.

During the existence of the school, about 1300 persons have attended its course.

As for the selection station in Kleinwanzleben*, it is one of the oldest, best-known, and wealthiest enterprises of this kind. It possesses enormous practical experience, has good scientific personnel, and has the most extensive laboratories; an idea of the scale of the latter may be given, for example, by the area—

…rization room, where 12 drilling machines are located, each of which is served by its own small independent laboratory, equipped with 2 analytical balances, the appropriate chemical workbench, and a polarimeter with automatic filling and emptying. Each such department is served by a staff of 7–8 persons. Selection is carried out in the most thorough manner; chemical analysis, characteristics and origin, as well as a photograph of each beet going into the operation, are entered in special books, thanks to which it is always possible, from these books, to trace the most remote kinship of each given beet obtained at the station.

In concluding this report of mine, I must add that during my trip abroad I completed and wrote up the work begun in Tomsk, “On the Rectification of Alcohol in Periodically Operating Apparatuses.”

This article was, in due course, sent for publication in the Proceedings of the Tomsk Technological Institute and was presented along with a separate report.

S. V. Lebedev

Tomsk
October 10, 1908.