BULLETIN

of the Siberian Institute of Technology. Siberia. Russia.

Vol. 47—Number—6.

1927.

BULLETIN

of the Siberian Institute of Technology.

Volume 47 (I). Issue 6.

S. V. Lebedev, Prof.

Analysis of the Phenomenon of Sugar Sifting

Tomsk.

1927.

Printed at the typolithography of the Tomsk Railway,
Makarovsky Lane, No. 6.
Tomsk, Okrlit No. 1312.
Print run: 350 copies.

S. V. Lebedev, Prof. STI.

Analysis of the phenomenon of sugar sweating as a guiding basis for the design and maintenance of sugar warehouses.

The question of storing sugar under industrial conditions, i.e., with large quantities of granulated sugar or refined sugar remaining for long periods in warehouses, has long attracted serious attention from practitioners and, later, theoreticians of the sugar industry. The reason for this is that the requirement of successful storage, ensuring the quantitative and qualitative integrity of sugar kept for a long time, in the overwhelming majority of cases proves practically impossible to fulfill. Drying out and, still more often, sweating of sugar, associated with its alteration and spoilage, appears to be an ordinary phenomenon, one that is especially pronounced at certain times of the year. In connection with this, beginning in the seventies of the eighteenth century, a whole series of articles appeared in the literature devoted to questions of the alteration of sugar during its storage.

Dwelling on the most important points, the following may be noted. Weinzierl¹ was the first, as early as 1869, to draw attention to changes in granulated sugar during its storage both in the laboratory—in jars—and in warehouses—in heaps. It was found that granulated sugar which was at first completely homogeneous, in the course of time became nonuniform in its chemical composition in different parts of the stored mass. The cause of this proved to be the flowing down, from the upper layers of the sugar mass, of syrup covering the surface of each sugar crystal with a thin layer; this syrup, gradually collecting in the lower layers of the sugar, caused its local relative deterioration. Thus, a purely mechanical cause of the change in the quality of sugar during storage was found.

Strohmer² studied the behavior of raw sugar during storage and broadened Weinzierl’s observation, establishing that spoilage of sugar also depends on changes in the syrup contained in the granulated sugar, whereas pure dry sucrose in a dry room can remain unchanged for years. In connection with the opinion that spoilage of sugar depends on the methods of its production (the presence or absence of bone-char filtration, sulfitation, etc.), Bodenbender³ and Degener⁴, investigating stored granulated sugars, found in them signs of inversion and established that, regardless of the methods of production, the absence of an alkaline reaction in sugar contributes to its spoilage during prolonged storage. The necessity of a certain alkalinity of sugar for successful storage is categorically confirmed by Lippmann⁵. E. and R. Melckebeke⁶ divide the causes of sugar alteration into internal and external ones. To the former they assign: the influence of alkalinity and the influence of the water content in the sugar; to the latter, i.e., external causes, they assign: the influence of microorganisms, temperature, and, finally, the action of water vapors “absorbed by the sugar.”

Later, the question of the relation of microorganisms to the spoilage of sugar during storage was raised and studied by Jesser¹, Roupé², Shorey³ and Gillot⁴, Geerlings and Kammerling⁵, Schöne⁶, Zettnow⁷, and others.

In general it has been established that sugar stored in warehouses always contains a sufficiently large number of diverse microorganisms. The latter can invert sugar and subject it to other further changes. However, the activity of microorganisms in stored sugar in most cases is not the primary process causing its spoilage, since the development of the microorganisms present in sugar requires certain conditions, above all heat and moisture. But there is too little of the latter in normal sugar sand and refined sugar for microorganisms to be able to manifest their vital activity in the mass of sugar. Therefore the development of microorganisms in sugar is usually preceded by processes of enrichment of the latter with moisture. Since all sorts of representatives of the microflora present in the air in general, and in particular in the air of the sugar factory and warehouses, as well as on sacks and, in general, on everything with which sugar comes into contact, get into sugar, there is no need here to enumerate individual representatives of the microorganisms discovered and possible in sugar under industrial conditions. It is obvious that the common Penicillium glaucum, various species of Aspergillus and Mucor, diverse bacteria—lactic-acid, butyric-acid, putrefactive—and many others occur here. Sometimes Leuconostoc, etc., also gets in.

All this indicates that concern for strict cleanliness in the factory and warehouse must not be lost sight of, as well as the dryness of the sugar and of the warehouse itself for its storage.

Geerlings⁸ regards moisture only as the first condition for the spoilage of sugar, while he attributes the actual cause of this spoilage: a) to the influence of the ash contained in the sugar, b) to the acidity of the sugar, and c) to the activity in it of microorganisms. Thus, to the other factors already put forward earlier, there is added still another new one, namely the negative influence on the keeping quality of sugar of the non-sugars contained in it.

M. K. Vasiliev⁹, who contributed very much by his work to elucidating the causes of the alteration of sugar during storage in warehouses, believes that the presence of moisture is an essential condition for the spoilage of sugar associated with the appearance of reducing substances and with loss of polarization. In Vasiliev’s opinion¹⁰, the dampening of sugar occurs for two reasons and each time takes place at the expense of the moisture of the air. The first of these is the hygroscopicity of that part of the intercrystalline medium which remains on the surface of the crystals. The second reason is the deposition of dew on cold sugar, when, owing to a rapid rise in the temperature of the outside air, the sugar in the warehouses does not have time to warm up quickly. Vasiliev attaches very great importance to the presence of reducing substances in sugar. He assumes that the quantity of reducing substances determines not only the degree of spoilage of the raw sugar, but also gives a certain idea of the time of storage, i.e. of its “ageing,” and of the capacity for further storage of the sugar. The concept of “reducing substances” has long been familiar to sugar and especially refinery production as a source

losses and with the detection of a reduction in the sugar’s capacity for storage. The chemical nature, conditions of occurrence, and role in production of reducing substances have been studied by many prominent scholars, as has been noted in a number of works and articles scattered both in foreign and in Russian literature. A general survey of works on this group of substances, still insufficiently studied from the standpoint of sugar production, is given by Prof. Kukharenko¹ in his “monograph” entitled “Reducing Substances and Their Role in Sugar Production.” It should be noted, as a fully established proposition, that unfavorable conditions of sugar storage may contribute to the accumulation of reducing substances in sugar, moisture and warming of the sugar being of substantial importance.

It is obvious that the influence of various factors to which sugar in warehouses is subjected may be either weakened or intensified by the conditions, method of storage, and arrangement of the warehouse itself.

With regard to methods of storing sugar, Stipel², on the basis of a review of the literature on this question, draws a general conclusion amounting to the following: “owing to uncertainty in establishing the true causes of sugar deterioration, rarely does anyone venture at the end of his work to give any definite indications as to the best methods of storing sugar.”

Aulard³ comes to the conclusion that the causes of sugar deterioration lie not in the sugar itself, but in the premises in which it is stored, and which very often are wholly unsuitable.

In view of the fact that the processes of change in sugar during prolonged storage are determined not only by its quality but also by the arrangement of the warehouse, and, moreover, depend to a certain extent on the time of year, the weather, on how often, when, and for how long the warehouse is opened, etc., Koydl⁴ comes to the conclusion that the results of individual experiments with one or another warehouse and the conclusions corresponding to them can be generalized and applied to the storage of sugar in other warehouses only with great approximation. It must be thought that it is precisely these reasons, along with the complexity of the chemistry of the decomposition and transformation of sugar during storage, that explain why the fairly rich literature on changes in sugar stored in warehouses is so poor in indications of rational methods of storage, and why it suffers from an almost complete absence of well-founded indications, and even merely factual data, on the construction of industrial sugar-storage facilities.

If one turns to the little that is available in this respect, one must encounter the extreme incompleteness and inconsistency of the existing material.

Vasil’ev⁵ considers it important that the arrangement of the warehouse should provide the stored sugar with the possibility, with the assistance of natural or artificial ventilation, of being easily and quickly warmed through. From this point of view, preference is given to wooden warehouses over stone ones. The same considerations require railroad-car-style stacking of sugar in separate piles, with passages between them, not allowing it to be laid in large continuous masses, e.g. in closed heaps, “in bulk,” i.e. masses that are little accessible to rapid warming. Heated warehouses are regarded as the most perfect warehouses, allowing the temperature of the warehouse and the humidity of the air to be freely regulated, maintaining conditions that exclude the possibility of dampening of the stored sugar.

Melckebeke ^1), for the successful storage of sugar with respect to the warehouse, sets out the following conditions: “the warehouse must be dry and unventilated. The floor should be cement, brick, or laid on cement. It is desirable to have an anteroom before the storeroom, so that the outer doors of the storeroom do not open directly to the outside. The storeroom must be divided into several compartments, so that the sugar always fills the entire space and is not exposed to the influence of a large volume of air. For the same reason, storage of granulated sugar in piles is preferred.”

Thus, the two opinions cited diverge sharply in their view of the necessity of ventilating the warehouse: one requires it as a necessary condition, while the other seeks to exclude it completely.

Basset ^2), as early as 1875, when considering “measures for preventing the deterioration of sugar during storage,” summarizes them briefly as follows—drying out as completely as possible and ventilating the warehouses, and moving them either from the first floor to spaces above well-ventilated and dry cellars. The storeroom should not be built on damp soil, and the air in it should from time to time, in dry weather, be ventilated. Doors and windows must fit tightly to their frames, so that they can be hermetically closed. Thus, in his view of the necessity of ventilating warehouses, Basset occupies an intermediate position between Melckebeke and Vasil’ev, though in his interpretation he approaches the former. All of Basset’s instructions dating from 1875, in the opinion of Prof. Herzfeld, are still worthy of attention even now.

The Hamburg Society for the Export and Storage of Sugar, in its rules for warehouses regarding the storage of sugar, says: “sugar must not be stored in places strongly exposed to atmospheric influences.”

According to the general opinion of owners of sugar warehouses, as reported by Professor Herzfeld in connection with his inspection in 1923 of the Hamburg sugar warehouses, sugar is best preserved in buildings made of corrugated iron, then comparatively well in wooden sheds, and worst of all in stone warehouses.

If one compares the advantage that has been revealed in practice, as indicated above, of warehouses made of corrugated iron—that is, warehouses that are almost hermetic and completely isolate the sugar within them from the action of atmospheric air—then this may be regarded as confirmation of the correctness of the view that requires the elimination of ventilation in sugar warehouses. It is obvious that this advantage of corrugated-iron sugar warehouses, if it indeed exists, can apply only to cases of storage of perfectly sound and dry sugar; otherwise, the positive aspects of completely isolating sugar from contact with the outside air may, under certain conditions, prove to be a drawback. The dependence of storability on the quality of the sugar has long been known in practice. In this case it is appropriate to recall what Herzfeld noted in his impressions from inspecting the Hamburg sugar warehouses: the employees of these warehouses unanimously stated that “the sugar of some factories is always preserved remarkably well, whereas other factories produce sugar that keeps poorly, and for this reason the warehouses try to avoid such sugars.”

The unequal hygroscopicity, and consequently also the durability, of different grades of sugar was also established by Prof. I. A. Kukharenko ^3) in 1918–19.

Although the literature concerning the construction of sugar warehouses and the procedure for caring for the sugar stored in them is extremely poor, nevertheless the practice of the sugar industry is extraordinarily interested in this question and therefore

^1) Ibid., 1905, p. 268.
^2) Guide pratique du fabricant de sucre, 1875.
^3) “Proceedings of the N. I. Department of Technological-Agricultural Production,” Prof. I. A. Kukharenko, 1925, vol. II, issue 3, p. 76.

for a very long time sought to establish precise practical rules for the storage of sugar. This may be seen, for example, from the already mentioned work by Basset—as early as 1875. The same striving to find practical conditions that would make it possible to store sugar in warehouses without risk of its spoilage led the “General Association of the German Sugar Industry” in 1902 to organize, on a broad scale, observations and experiments on the storage of sugar in warehouses. The principal question to be resolved was whether the alkaline reaction of sugar to phenolphthalein is an indispensable condition for its good keeping quality or not. This question was connected with the experiments of the Silesian Branch of the Association, which showed that the high alkalinity of sugar during storage gradually decreased, and that with the passage of time such sugar became neutral and even acidic.

Thus, the practical interest in questions of sugar storage in the experiments indicated above was concentrated on elucidating the chemistry of the decomposition of stored sugar in connection with its enrichment in reducing substances under conditions of a definite alkalinity.

The rational arrangement of warehouses, the procedure for servicing them that ensures the greatest preservation of sugar, the role of ventilation in this respect, and similar questions—most important and at the same time painful questions of sugar storage—were, in essence, left entirely untouched in these experiments, although observations of the temperature conditions and humidity of the warehouses were naturally included in the program of the experiments.

Limiting ourselves to what has been noted above regarding the treatment in the literature of questions of sugar storage during the period from 1896 to the present, let us turn to what the sugar industry is guided by in practice, and how it solves its tasks in this field.

What was considered necessary for the successful storage of sugar 50 years ago may be seen from what was recommended in this respect in the already mentioned work by Basset of 1875. The corresponding practical instructions for the period around 1900 concerning the arrangement of warehouses are also given by the already cited work of Melckebeke, which was a development of the topic concerning the conditions of prolonged storage of sugar and the changes it undergoes in the process.

The practical rules for the care of sugar stored in warehouses are illustrated, for the same period of time, by the rules for the storage of sugar issued by the Hamburg Association for the export and storage of sugar as guidance for its warehouses. Apart from observations of the integrity of the packaging, the measures prescribed here amount only to the following: sugar should not be stacked close against the walls; it should be isolated from the floor by means of wooden trestles and a flooring laid upon them; and, together with or near the sugar, goods should not be stored which, by their moisture, odor, or other properties, might exert a harmful influence on the sugar present in the warehouse. M. K. Vasil’ev also devotes some attention to the arrangement of warehouses and the care of sugar in them. In this direction he confines himself only to general indications, although through his substantial investigations and observations of the dampening of sugar in warehouses he clarified a great deal concerning the processes of sugar decomposition, the accumulation of reducing substances in it, and so forth.

In order to ascertain how the task of the successful storage of sugar is solved by the modern sugar industry, let us turn to the instruction of Sakharotrest, proposed “for guidance and execution” to its warehouses in the localities. In this instruction “on the storage and transport of sugars,” dated September 23, 1924, the technical requirements imposed on a warehouse are presented in paragraphs 4 and 5; the procedure for receiving, stacking, and distributing sugar is established by §§ 6 and 7; the procedure for servicing the warehouse and the permissible norms of loss during storage are indicated in § 8. All the remaining content

The “Instructions” concern the economic, commercial, reporting, etc., aspects of warehouse life. In the part of the instructions that interests us, connected with §§ 4–8, everything concerning the receipt, stacking, and partly the care of sugar stored in warehouses is presented quite fully in §§ 6 and 7¹. The exact opposite may be said of the part of the instructions concerning the care of the warehouse, which is represented by only one § 8. The text of this paragraph, entirely solitary in its content and not supported by any guiding indications or explanations of the essence of what is recommended here, given the limited awareness of warehouse personnel in the localities, may lead to results entirely opposite to those desired. Indeed, what should be understood by the expression: “The warehouse must be regularly ventilated”? How is this word—“regularly”—to be interpreted? Does it mean ventilating the warehouse once a month, or once a week, or daily, in the mornings, or perhaps during the day, or something else? Who will answer these questions, quite natural and even inevitable there in the localities where there is no experience and knowledge of the matter, if there are no corresponding indications in the “Instructions” themselves? Further, in the same § 8 it is stated: “On clear, dry, sunny days the windows and doors (of the warehouse) should be opened, for which purpose they must be fitted with grilles.” It may be asserted with complete confidence, without risk of error, that this measure, essentially correct in certain cases, when recommended in such a form, will very often lead to planned, systematic, and large-scale dampening and spoilage of sugar in warehouses. The reason for such possibilities lies in the complete absence, in the instructions, of any linkage between these “clear, dry, and sunny days,” when warehouses are to be opened, and the weather preceding them. If these clear days come unexpectedly at the beginning of a friendly, swiftly advancing spring, as for example in Siberia, with a sharp rise in temperature, when these days may immediately be preceded by a period of considerable cold and when, after a severe winter, the sugar in the warehouses still retains a very low temperature corresponding to the winter season, then it is obvious that such opening of the doors and windows of warehouses, often facing the southern sunny side, will inevitably cause the mass dampening of the greater part of the sugar stored in such warehouses.

In view of all this, it must be acknowledged that § 8 of the instructions, i.e. the point concerning the care of warehouses, requires considerable supplementation, expansion, and the most serious elaboration, so that it may acquire the significance and bring the benefit that is evidently expected of it. This paragraph should also include instructions on the care of sugar stored in warehouses, both in general and in the case of sugar that has become damp. In this connection, the same § 8 should also contain the indications from § 6 that “all shifting of sugars must be avoided,” as well as the whole of § 7 concerning refined-sugar molasses.

As for the technical requirements imposed by the “Instructions” on the arrangement of sugar warehouses, it must evidently be accepted, with regard to this, that the given part in the form of §§ 4 and 5 has as its aim merely the desire to suggest general grounds for selecting locally, from the existing “stock of warehouses,” those most suitable for the tasks of storing sugar. In this sense §§ 4 and 5 of the instructions fully exhaust the indicated task. At the same time it is obvious that indications of this kind have absolutely no bearing on the question of how a rationally constructed warehouse for storing sugar should be designed; an answer to this must be found somewhere else.

This question, generally of importance for the sugar industry, under the present working conditions of Sakharotrest acquires special significance for it. This is due to the fact that the task of distribution among the population

The entire mass of the sugar produced now falls almost wholly upon Sakharotrest. Naturally, this requires long-distance transport and is associated with concentration, in certain places, of large masses of sugar stored for long periods in warehouses. This situation is now inevitable because of the relatively small number, as compared with prewar times, of private and other commercial and industrial enterprises, which quickly took sugar from the warehouses for sale to the consumer population. Under such conditions, in local district warehouses, although at times a considerable quantity of sugar was concentrated, these accumulations nevertheless changed continuously and rapidly: on the one hand, dispersing among trading enterprises, and on the other, being replaced by sugar newly arriving from the factories. At the present time, however, such district warehouses, especially in places considerably distant from sugar factories, as, for example, in Siberia, have chiefly the significance of warehouses for the long-term storage of sugar that remains there during those periods especially threatening with dampening, namely spring, summer, and even autumn—something such Siberian warehouses formerly hardly knew. In view of this, the fate of the sugar being stored under such conditions, and consequently concern for the construction of rationally built warehouses, enters the circle of immediate and closest concerns of the sugar industry of the U.S.S.R. This circumstance, apparently, is the reason why in 1925 Sakharotrest submitted for resolution the question of developing foundations for the construction of sugar warehouses. How this was resolved may be seen from the corresponding resolution of November 4–5, 1925, of the Sakharotrest Commission for the development of standards for factory structures—in the present case, for sugar warehouses. This resolution reads as follows:

“The sizes of warehouses (for granulated sugar) are adopted depending on the productivity of the factory. For one square sazhen (4.5 sq. meters) in granulated-sugar warehouses, a load of 1500 poods is permitted when stacked in 25 rows. For design purposes, three types of warehouses are to be adopted: for 75,000 poods, 100,000, and 150,000 poods. Warehouses of greater capacity are to be built according to individual designs. The height of the warehouses must be such as to make it possible to stack 25 rows of sacks. The warehouse premises must be permanent, with steam heating; beneath the floor a crawlspace must be arranged with appropriate ventilation. The light area is to be 5% of the floor area. Doors (gates) must be sliding, on rollers, with two grilles installed. The locations of the gates must be chosen with provision for ventilation.

“In refinery warehouses, a load of 750 poods per square sazhen is permitted, calculated for 10 rows of sacks over the height of the warehouse. Two stories may be permitted, provided that the floor slabs between stories are made of iron or reinforced concrete. In two-story warehouses mechanical hoists are necessary. Otherwise, the same as in granulated-sugar warehouses.” A supplement to this is the resolution issued on December 29, 1925, by the meeting of directors of refinery plants on the question of standardizing the storage of granulated sugars in warehouses. This resolution is as follows: “The storage of granulated sugars must be carried out by a mixed method, i.e., in the lower part of the warehouse in bulk (in bins), and in the upper part the granulated sugar is stacked in sacks. In this case the capacity of each bin must be equal to the 10-day raw-material requirement of the refinery plants.

“Granulated-sugar warehouses must be heated. Ventilation of the warehouses is necessary.”

From the resolutions cited it is evident that the principal positive features, established in the past in the development of this field, have been included by Sakharotrest in the modern interpretation of the rational arrangement of warehouses for sugar storage. These provisions amount to the following: heating of warehouses, their ventilation, the permanent character of the warehouses, insulated roofs, and a ventilated crawlspace.

A certain peculiarity is the tendency to increase the height of the warehouse, connected with the requirement that sugar be stacked to a height of 25 rows of sacks. Thus, these provisions of warehouses introduce nothing new into the arrangement of sugar warehouses. At the same time, assignments concerning the required heating and ventilation have been left without any guiding indications. It is obvious that the absence of this in the construction of warehouses will inevitably raise the question of what requirements are to be imposed upon this ventilation and heating of warehouses, and what conditions of their practical use must be taken into account in their calculation and installation.

Prof. Zuev, in volume IV of his Encyclopedia of Beet-Sugar Production, published in 1926, says¹): “The question of the best preservation of granulated sugar belongs to the number of little-developed questions; as proof of this one may cite the fact that among specialists up to the present time there exist various opinions as to whether a sugar warehouse should be heated, what temperature is most desirable, to what extent the ventilation of such a warehouse should be carried out, and so forth.”

In this connection, giving a general summary of previous works and dwelling on the processes developing in stored sugar, Prof. Zuev arrives at a definite conclusion as to the necessity both of heating and of ventilating warehouses for granulated sugar, since “without this the stored sugar represents capital essentially condemned to the whim of fate.”

While introducing nothing essentially new into the fundamental propositions and interpretation of the essence of the questions of sugar storage, in the above-mentioned work Prof. Zuev gives abundant material, of a purely constructional character, on the arrangement of sugar warehouses, on the installation and calculation of their heating and, in part, ventilation. This to a considerable extent fills the gap in the previous works in the corresponding specialized literature that had existed until recently. However, despite this new contribution to the development of the question of sugar storage, much fundamental and essential remains in it that has so far either been very insufficiently treated or not touched upon at all.

Here, first of all, belongs the clarification of the question of the significance of the warehouse as an intermediate factor in the interrelation between the external atmospheric air and the sugar stored in the warehouse. Moreover, the warehouse, considered from this aspect, is for the stored sugar that air interlayer, that sort of buffer, which directly takes upon itself the meteorological shocks and shifts occurring in the atmospheric air—sometimes very sharp and unexpected—and transmits them under such conditions to the sugar in a softened form. In this connection, the question of the temperature regime of the warehouse and its changes over time appears essential, since the usual assumption of uniformity of temperature inside the warehouse, excluding the spaces directly adjacent to the external walls and the floor, must for many reasons be considered entirely erroneous.

Among the questions hardly touched upon should also be included the question of the conditions of ventilation of warehouses and of the methods of carrying it out.

All that has been set forth above indicates that the conditions of industrial storage of sugar in warehouses are still very insufficiently and, moreover, unevenly elucidated. If the available material concerning the change and destruction of sugar during storage may be considered rich and varied, then one must acknowledge an extreme paucity of information not so much about the destruction of sugar itself as about what causes its occurrence, what processes take place here, and how they develop in their first stage, when, very probably, there are as yet no external manifestations of destruction of the stored sugar.

¹) p. 332.

Obviously, this is a fundamental question, the clarification of which may elucidate much and, in particular, shed light on the necessity and expediency of one or another arrangement of the warehouse, on the ventilation and heating installations needed for it, and also on the procedure for caring for the stored sugar and the conditions of servicing sugar warehouses in connection with their airing and heating.

In all works relating to the study of the causes of changes in sugar during storage in warehouses, there are invariable fundamental errors in the approach to the solution of this question. They consist in treating stored sugar as a body completely homogeneous throughout its mass, similar to the way this is the case with water, air, etc.

In reality the situation is different, since sugar, whether it be granulated sugar or refined sugar, is far from homogeneous, but consists of pure sucrose, a mass of air filling the intercrystalline space, and, finally, a mass of molasses covering, to a greater or lesser extent, the surface of the sucrose crystals. The air space of sugar must be considered as an inseparable and, moreover, highly characteristic part of the mass of sugar, possessing its own distinctly expressed properties, quite different from those of sucrose and molasses. This circumstance is of essential importance with regard to the possibilities of changes in sugar during storage under the influence of the totality of external factors, differently perceived by each of its constituents.

Thus, in striving toward a more accurate elucidation of the primary causes of sugar spoilage and wishing to find means of eliminating them, it is necessary to regard sugar as something like a conglomerate consisting of pure crystalline sucrose, a mass of air penetrating it, and an intermediate medium—molasses, which in individual cases may be absent. It is in the entirely independent consideration and analysis of the relation of each constituent of sugar to the action of individual external factors of the surrounding environment, and in the clarification of the consequences of these actions for sugar as a whole, that one should seek the path toward a more precise establishment of the primary cause of sugar spoilage during storage. The elucidation of this may also lead to definite indications of possible means of protecting sugar from spoilage while it is in warehouses.

Since the action of external factors is transmitted to the stored sugar through the air space of the warehouse, it therefore seems essential to determine the state of this space and its change over time in the presence of a mass of sugar in the warehouse and under conditions of the usual fluctuations and successive changes in the state of atmospheric air, both in general and according to the seasons of the year.

However dry the refined sugar may be, the air of its intercrystalline space always contains a certain amount of water vapor, provided the sugar has not been subjected to special final drying and if it does not remain unconditionally isolated from contact with the external atmospheric air. The inevitability of this is determined by the constant, even if minimal, humidity of the latter.

Thus, in sugar, besides sucrose and dry air, there is usually also a certain amount of water, which determines the moisture content of the sugar.

At the minimum moisture content of sugar, the water contained in it is present only in the form of vapor, to a greater or lesser extent saturating the air of the intercrystalline space. At a higher moisture content of the sugar, besides water vapor, it also contains water in a droplet-liquid state, entering into the composition of the molasses distributed over the surface of the sucrose crystals.

Knowing the porosity of sugar, it is possible to establish its limiting moisture content, excluding the possibility of molasses being contained in it. This is the case when the moisture content of the sugar is determined only by the amount of water present in the state of vapor, in the absence of droplet-liquid water in the form of molasses.

Assuming, following Prof. Smolenskii, the porosity of refined sugar to be 18.7% by volume, the specific gravity of refined sugar \(=1.230\), the specific gravity of sucrose \(=1.5805\), and assuming that the water vapors in the intercrystalline space are in a state of saturation, it is easy to find the quantitative content of water in the sugar, i.e., to establish its moisture content in percent by weight.

It is obvious that the amount of water present in the intercrystalline space of refined sugar in the state of vapor depends on the usual factors determining this, i.e., on pressure and temperature. Since fluctuations of atmospheric pressure fall within relatively narrow limits and therefore cannot be of essential significance, in what follows we shall take the pressure to be normal. As for the change in the temperature of the outside air, this may be taken, within the region of transport and storage of sugar in Siberia, as varying from \(-40^\circ\) to \(+40^\circ\text{C}\).

In connection with what has been adopted, the quantity of water vapor saturating the space in one cubic meter of air at a pressure of 760 mm will be expressed, in kilograms, for individual temperatures within the limits indicated above by the figures given in the table below.

TABLE 1.

Temperature in °C	Water content in 1 cubic meter of air saturated with vapors, in kg
\(-20^\circ\) C	0.001060 kg
\(-10^\circ\) »	0.002303 »
\(0^\circ\) »	0.004876 »
\(+4^\circ\) »	0.006370 »
\(+6^\circ\) »	0.007259 »
\(+10^\circ\) »	0.009372 »
\(+20^\circ\) »	0.017177 »
\(+30^\circ\) »	0.030130 »
\(+40^\circ\) »	0.196340 »

TABLE 2.

Temperature in °C	Water content in the pores of one cubic decimeter of refined sugar, in grams
\(-20^\circ\) C	0.198 kg
\(-10^\circ\) »	0.431 »
\(0^\circ\) »	0.912 »
\(+4^\circ\) »	1.191 »
\(+6^\circ\) »	1.357 »
\(+10^\circ\) »	1.752 »
\(+20^\circ\) »	3.212 »
\(+30^\circ\) »	5.634 »
\(+40^\circ\) »	36.711 »

If the data of Table 1 are referred to the volume of the intercrystalline space of one cubic decimeter of refined sugar, i.e. to 187 cu. cm, then we obtain the following quantities of water, in the state of vapor contained also in the pores of refined sugar taken in the indicated volume, expressed in grams in Table 2.

With the above-adopted specific gravity of refined sugar, \(=1.230\), and with the permissible technical standards for its moisture content of 0.3% by weight, the total content of water in it per one cubic decimeter will be \(1230 \times 0.003 = 3.69\) g. Comparing this figure with the quantities giving the possible maximum content of water in the form of vapors in one cubic decimeter of refined sugar, one can see that at \(+20^\circ\text{C}\), refined sugar already contains almost no water in a drop-liquid state and thus proves to be actually dry. It is obvious that with an increase in the temperature of the surrounding atmospheric air, a decrease in the moisture content of refined sugar, i.e. its drying, will prove completely impossible. The reason is that, with the heating of the air, its humidity rapidly increases, becoming higher than the humidity of the air filling the intercrystalline space of the refined sugar. If, for example, the relative humidity of the atmospheric air is 70%, then already at \(30^\circ\text{C}\) it, judging from Tables 1 and 2, proves to be more humid than the intercrystalline space of refined sugar with the technically permissible water content for it of 0.3% by weight of sugar. This indicates that the specified standard has been established correctly and that the possibility of drying the refined sugar is either almost or even entirely excluded by it. However, this occurs only on the condition that the atmospher-

the air is heated to \(+20^\circ\) C, or higher. In the opposite case, i.e. when the air is cooled below \(+20\), the situation changes. In this case the refined sugar under consideration, i.e. with \(0.3\%\) moisture, which until then had appeared dry, becomes damp; moreover, its dampening increases with a further lowering of the temperature. The cause of the observed phenomenon is that, when refined sugar with the indicated content of \(0.3\%\) is cooled, the water vapor present in it at \(+20^\circ\)C in a state saturating the space begins to condense, gradually precipitating in the form of dew throughout the mass of the sugar. As a result there is formed a layer of liquid which, corresponding to the intercrystalline space of the refined sugar, has a surface of 3–5 square meters per 1 cubic decimeter of refined sugar.

Thus, when refined sugar is cooled below \(+20^\circ\)C, its moisture content does not change quantitatively, but its form becomes different, since, alongside water vapor, water also appears in the refined sugar in a drop-liquid state. This latter circumstance has its undesirable and understandable consequences. One of them is the drying-out of refined sugar, although, judging from Table 1, the moisture capacity of cold air falls rapidly as its temperature is lowered and, consequently, the threat of the refined sugar absorbing excess moisture from the atmospheric air would seem gradually to disappear. However, this possibility is in reality not eliminated even when the temperature around the cooling refined sugar, with the humidity permissible under present technical standards, falls even to the limits of the most severe Siberian frosts. This is due to the fact that in the intercrystalline space of refined sugar cooled under these conditions there will still be air saturated with water vapor at the given temperature, whereas the relative humidity of the atmospheric air does not exceed 60–70%. The consequence of this, with free contact between the sugar and the atmospheric air and with the possibility of its circulation around the refined sugar, will be a certain absorption by the air of the moisture of the refined sugar and some drying-out of the latter. This phenomenon is noticeably intensified if the temperature of the refined sugar proves to be higher than that of the surrounding air. In this case the drying-out is manifested the more strongly, the warmer the sugar is in comparison with the air in contact with it. The reason for this is clear: dry cold atmospheric air, being warmed upon contact with relatively warm refined sugar and increasing its moisture capacity, obtains the ability to take from the sugar its excess moisture under these conditions, and does so the more vigorously, the greater the temperature difference between the sugar and the air in contact with it. Naturally, artificial circulation of air must increase the drying-out of the sugar. Since all the conditions noted here for the drying-out of sugar occur in Siberia when refined sugar is transported in winter by rail, this explains the many-times-observed loss in weight of refined sugar packed in sacks and sent in winter to Siberia. From what has just been said it also follows that loading warm sugar into wagons, for example directly from the factory and not from warehouses, can likewise have its negative significance.

In connection with what has been considered, the following proposition becomes clear: the maximum permissible moisture standard for obtaining dry refined sugar is determined by the quantity of water vapor in a state of saturation corresponding to the intercrystalline space of the given refined sugar at the lowest temperature possible for it during storage, transportation, etc. Thus, the highest moisture content for refined sugar that excludes the possibility of its becoming damp when cooled, owing to the formation in it of drop-liquid water, is determined by the specific weight of the refined sugar, its porosity, and the lowest temperature possible for the atmospheric air surrounding the given refined sugar. By mutually relating all this, we obtain equation 1, whence follows equation (2), which gives a definite mathematical expression for the greatest moisture content of refined sugar that can be permitted in production.

\[ D \times V \times W_{\max} = P \times V \times St \qquad (1) \]

whence

\[ W_{\max} = \frac{P \times St}{D} \qquad (2) \]

Where:

\[ \left\{ \begin{array}{ll} D & \text{— specific gravity of refined sugar,}\\ V & \text{— volume of refined sugar in cubic meters,}\\ W_{\max} & \text{— moisture content of refined sugar in percent by weight,}\\ P & \text{— porosity of refined sugar in \% of its total volume,}\\ T & \text{— lowest temperature of the atmospheric air surrounding the refined sugar,}\\ St & \text{— content (in kg) of water vapor in one cubic meter of saturated air vapor.} \end{array} \right. \]

Substituting into equation 2 the quantities corresponding to the case under consideration, i.e., taking \(D\) equal to 1.230; \(P = 0.18\%\), and successively entering from Table 1 the values corresponding to different temperatures, we obtain the numerical values of the maximum moisture permissible in refined sugar at different temperatures within the range from \(+30^\circ\) to \(-20^\circ\) C. The numerical values thus obtained are presented in Table 3.

TABLE 3.

Lowest temperature permissible for refined sugar, in °C	Corresponding maximum moisture content of refined sugar, in percent by weight
\(+30^\circ\) C	0.47%
\(+20^\circ\) C	0.26%
\(+10^\circ\) C	0.14%
\(+4^\circ\) C	0.13%
\(-4^\circ\) C	0.12%
\(0^\circ\) C	0.07%
\(-10^\circ\) C	0.04%
\(-20^\circ\) C	0.02%

It follows from the data of the table that the maximum permissible moisture content in refined sugar is not a constant quantity, but changes sharply with a change in the lowest temperature possible for the refined sugar. Of course, besides temperature, the specific gravity of the refined sugar and its porosity are also of known, though lesser, importance; therefore both must be taken into account individually for each grade of sugar. The corresponding numerical values for different grades of refined sugar can be found in the experimental data of Prof. Smolensky, given below in Table 4.

TABLE 4.

Grade of refined sugar	Specific gravity	Porosity
Sawed, head sugar . .	1.231
» » . .	1.194
Chopped » . .	1.270	18.7%
Pressed . . . .	1.330—1.357	13.3%
Sucrose . . . .	1.561—1.62
» (according to Gerlach)	1.5805

The proposition illustrated by Table 4 has practical significance, indicating that the moisture content of refined sugar sent to southern countries may be considerably higher than that of sugar sent north. If, instead of sacks, boxes, barrels, or other air-impermeable packaging are used, this, of course, excludes the possibility of the refined sugar drying out; however, it does not eliminate the possibility of its becoming moist upon cooling. From a comparison of the data

from Tables 1, 2, 3, and 4 it follows that, for refined sugar going in winter to Siberia and, in general, to northern regions, the highest moisture content of refined sugar must in this case be considerably lower than the currently customarily permitted one, namely 0.3% by weight of the refined sugar, quite correctly established for the central and southern belt of European Russia and the corresponding other climatic regions with a short and comparatively warm winter.

Taking as an average the lower temperature that is at times steadily maintained in Siberia during the winter, equal to \(-20^\circ\) C, judging from the data of Table 3 it must be assumed that the permissible moisture content of refined sugar sent in winter to Siberia should correspond to only 0.02% by weight of the sugar. However, investigations by the author, carried out in 1925 on refined sugar that had arrived in Tomsk from European Russia during December–March, when the ambient temperature sometimes fell to \(-40^\circ\) C, showed that even under these extreme conditions a moisture content of refined sugar up to 0.10% precludes its drying out en route. A further increase in moisture already threatens drying out, and with the moisture content of 0.30% allowed by the technical standards, refined sugar usually arrives with drying losses reaching, in individual cases, 50–60 kilograms and more per wagon of sugar.

The drying out of refined sugar, which is the phenomenon of evaporation of the water contained in it, is to a certain extent explained by the dependence established already by Dalton, who gave a mathematical expression for the rate of evaporation of a liquid in relation to the various factors determining it. It was found that this rate is proportional to the free surface of the liquid—\(S\), proportional to the difference between the elasticity—\(R\) of saturated vapors at the temperature of the evaporating liquid and the elasticity—\(r\) of the vapors already present above the liquid. In addition, it is inversely proportional to the elasticity—\(H\) of the foreign gas (in the case under consideration, air) located above the liquid. All this leads to the formula ¹):

\[ V=\frac{C \times S}{H}(R-r) \]

where \(C\) is a constant factor depending on the speed of motion of the air or wind. In further development of the proposition given by Dalton, it has been established that \(V\) is inversely proportional to \(H^n\), where “\(n\)” is a quantity depending on the nature of the evaporating liquid and on the gas surrounding it; for example, in air for water \(n=1.18\). According to Stefan’s investigations, during the evaporation of a liquid in vertical tubes, in which a layer of saturated vapor forms above the very surface of the liquid (a case corresponding to the conditions of drying out of refined sugar), slowly diffusing toward the open aperture of the tube, the rate of evaporation is inversely proportional to the distance of the liquid level from the open end of the tube.

The just noted dependences, established by Dalton, Laval, and Stefan, while serving as direct confirmation of what has already been analyzed above concerning the causes, conditions, and degree of drying out of refined sugar, at the same time serve as a certain supplement to the conclusions drawn. Here, for example, the significance of the size of individual pieces of refined sugar in the process of its drying out comes to the fore. Without entering here into a further detailed analysis of the question under consideration, let us make a summary of the general conclusions to which all the foregoing leads. These conclusions are as follows:

1) Refined sugar should be regarded as dry when its moisture content is determined by the presence in it only of aqueous vapors.

2) The appearance of water in refined sugar in a droplet-liquid state is a sign of its becoming damp.

¹) Physics, by Khvolson, Vol. III, p. 484.

3) The technical norm for the maximum moisture content of refined sugar varies depending on the lower temperature admissible for the given refined sugar.

4) The technical norm for the maximum moisture content admissible in refined sugar—\(W\max\)—is proportional to the porosity of the refined sugar, expressed in volume percent of it—\(P\); proportional to the content of water vapor in the state of saturation in one cubic meter of air \(St\) at the lower temperature admissible for the given refined sugar—\(t\), and inversely proportional to the specific weight of the refined sugar—\(D\), i.e.

\[ W\max = \frac{P \times St}{D} \]

5) Lowering the temperature of refined sugar below that adopted in calculating its limiting moisture content leads to dampening of the refined sugar.

6) Drying of refined sugar in the absence of tight packing is possible at all temperatures both above and below \(0^\circ\), provided that the sugar is warmer than the air surrounding it and that the moisture content of the latter is lower than the moisture content of the air filling the pores of the sugar.

7) In order to eliminate the possibility of undesirable dampening and drying of refined sugar, the moisture content admissible for it, \(0.3\%\) by weight, has been established correctly for the middle and southern zones of European Russia and for analogous climatic regions; whereas for refined sugar sent in winter to more northern regions, where prolonged winter frosts reach \(-20^\circ\) and below, the maximum moisture content of refined sugar should not exceed \(0.10\%\) by weight.

The conclusions given above are a consequence of definite interrelations of external factors—in the case considered, temperature conditions—with one of the components of refined sugar, namely, the air of its intercrystalline space. As is evident from the preceding, these conclusions, while representing a certain theoretical interest, also have practical significance. However, the conclusions indicated still do not exhaust the question of the influence of external temperature changes on refined sugar. Considering the relation of the air of the intercrystalline space outside any connection with the mass of crystalline sucrose, and assuming it to be completely isolated and independent in its state from atmospheric air, we have thereby considerably simplified the phenomenon under discussion. It is obvious that temperature changes create, with respect to refined sugar, conditions that involve the mass of its crystalline sucrose in definite interrelations not only with the air of the intercrystalline space of the sugar, but also with the atmospheric air surrounding it.

The essence of this interrelation lies not so much in the air itself as in the water vapors contained in it, and in the possibility that, with changes of temperature, the latter may either condense or again evaporate. Approaching from this side the question of the influence of temperature fluctuations on refined sugar, it must be taken into account that everything said about the change of vapors in the intercrystalline air in sugar applies in full also to the atmospheric air surrounding this sugar.

Consequently, under a certain cooling, refined sugar becomes damp to the same extent both within the whole mass and on the outside. The former occurs through the precipitation of water from the air of the intercrystalline space of the sugar, the latter through the same phenomenon, but in the atmospheric air. In this sense there is no difference between the relation to sugar of the one air and the other. But with respect to the quantity of water that can, over time, condense on the surface and in the mass of the sugar under the influence of current meteorological fluctuations of the outside air, there is a very significant difference between these two cases.

The air of the intercrystalline space of refined sugar, at a definite volume of the latter and with the moisture capacity of that air being limited in the case of its complete isolation from atmospheric air, can over time yield, as was already clarified earlier, only a definite and, moreover, very insignificant quan-

the amount of dew released within the mass of cooled sugar. The latter, being quantitatively dependent on temperature conditions, as is self-evident, cannot be increased by repeated, even multiple, cooling. Therefore the possible degree of dampening within the mass of sugar at the expense of the moist air contained in it proves to be definitely limited and quantitatively dependent on the initial temperature, the moisture content of the sugar, and the extent of its subsequent cooling.

The situation is otherwise with the quantity of water vapor that, over time, can condense from the external air on the outer surface of the sugar in contact with it. The characteristic feature of this case lies in the unlimitedness, in comparison with the mass of sugar, of the mass of atmospheric air in contact with it, and also in the constant supply to the latter of new quantities of moisture from the surrounding medium in place of that which has fallen out of it. Under such circumstances conditions are created that turn the atmospheric space into an inexhaustible reservoir, capable, over time and with corresponding temperature fluctuations, of depositing on the surface of the dampening sugar indefinitely large quantities of water condensed from the air.

Thus, under certain temperature conditions, the interaction of air and sugar leads to external and internal dampening of the sugar, which is expressed in the appearance of a layer of water over the entire surface of the crystalline sucrose constituting the mass of sugar. It is obvious that this must lead to the dissolution of sugar. To what extent, however, this actually takes place depends on how the phenomenon of sweating of sugar develops in its initial stage. Whether such sweating of sugar begins gradually and then slowly increases, persisting for a long time thereafter, or whether the phenomenon develops rapidly and then quickly disappears; finally, what external factors play a role here and to what extent—all this, and much else, is of essential importance with regard to the possibility of dissolution of crystalline sucrose, the sweating of sugar, and, consequently, the further retention by this sugar of the dew that has fallen upon it. Elucidation of all this may, to a certain degree, clarify the conditions under which dampening of sugar develops, the probable extent of it, and also indicate means which, if they do not eliminate it, may perhaps reduce the intensity of manifestation of this process leading to spoilage of sugar.

In dwelling on the questions raised, it must be noted that the literature in this direction, apart from numerous indications of the very fact of dampening of sugar, offers nothing further.

In connection with this, in order to elucidate the conditions governing the development of dampening of sugar in the first stages of this process, and to clarify the relation of the sugar itself to it, it was necessary to undertake a special experimental investigation.

The aim of the experimental work presented below, carried out by Prof. S. V. Lebedev jointly with N. G. Zagibalov, is to clarify the question of how the process of dampening of sugar unfolds in the first stage of its development, and also to what extent and under what conditions the retention by sugar of moisture deposited on it in the form of dew takes place.

The essence of this work is reduced to reproducing the sweating of cooled sugar under changing conditions with respect to the temperature of the sugar and of the air surrounding it, as well as the humidity of the latter. Observations on the course of the process are made by changes in the weight of the sugar. The material for the work could have been either granulated sugar or refined sugar; however, the greater cleanliness and convenience of form for handling forced preference to be given to refined sugar. For the experiments it is used in the form of regular cubes cut from a definite layer of a single sugar loaf. The cubes were of various sizes, with edges from two to five centimeters, i.e. with weights from 35 to 150 grams, the upper limiting size being determined by the possibility of

weighing on an analytical balance. In view of the heterogeneity of the structure of refined sugar in a sugar loaf, in order to ensure the greatest possible identity of the experimental material, the cubes were cut out from layers parallel to the base of the sugar loaf, taking them from each layer at the same distance from the axis and from the outer surface of the loaf.

The basic principle of the chosen method of work was that a preliminarily weighed cube of sugar, uniformly cooled in a volume of air definite as to its state, is transferred to other conditions of the air medium, with a comparatively elevated temperature and, in particular cases, a changing humidity. In each individual case the cold sugar thaws out in different ways, condensing on itself, to varying degrees, moisture from the surrounding medium. The amount of moisture retained or lost by the sugar is determined by successive weighings. The warming of the sugar was induced in a specially arranged thermostat—a cabinet fitted for heating with twelve electric bulbs uniformly distributed inside the thermostat, switched on as needed by external plugs. To create the necessary humidity in the thermostat, broad strips of cloth, automatically and continuously moistened, were suspended throughout the height of the thermostat chamber, their lower ends being lowered into trays of water. Inside the chamber, at different heights, were placed thermometers, psychrometers, and also an electric fan for mixing the air inside the chamber. In the presence of sugar the fan was not set in motion. In a chamber arranged in this way it appeared possible easily to regulate the temperature and humidity, maintaining the required conditions by means of the indicated devices.

Technically the experiment was carried out as follows: individual cubes of sugar of various sizes—of surface and weight precisely established for each cube—are tied crosswise with thin silver wires and suspended by them in hermetically closing glass jars. The jars are taken with a volume as close as possible to the volume of the freely suspended sugar cube placed in them. Each jar is equipped with a thermometer. The cooling of the sugar, which lasted not less than twenty-four hours, was carried out in the indicated jars; the temperature of the air space inside the jar was taken as the temperature of the cooled sugar cube contained in it. Cooling was effected directly by outside air, making use of the Siberian winter cold and an unheated laboratory room, and also by means of an ice chamber. The purpose of using closed jars during the cooling of the sugar lay in the desire to eliminate during this period the influence of air in general, and in particular atmospheric air, which may lead to significant changes during cooling in the preliminarily established weight and moisture content of the refined-sugar sample under investigation.

The cube of refined sugar cooled to one or another temperature established by the thermometer is transferred from the jar into the thermostat chamber of the described device, where it is suspended on its wire, being placed directly in the air space of the thermostat with a definitely established and maintained humidity and temperature. Subsequently the tested cube is weighed again on an analytical balance. The intervals of time between the first weighings are taken as 3–7 minutes, the subsequent ones longer: from 10 to 20 minutes.

The total duration of the cooled sugar’s stay in the chamber ranges from half an hour to two or more hours. During the indicated time each cube, depending on the experimental conditions, is weighed from two to eight times. By changing the degree of cooling of the sugar, the humidity, and the temperature of the chamber, it was possible, following the method adopted, to trace the development of sugar thawing under the most varied conditions.

Cases of a decrease in the weight of the sugar speak of the process of its drying. The necessity of periodically weighing the sugar that is becoming moistened, and the associated brief removal of it from the humid chamber-thermostat, of course introduces disturbing influences into the observed process. However, the deviations in the degree of moistening caused by this are very slight, both because of the short duration of the weighing and because the main effect of moistening is concentrated, as we shall see from what follows, in a very short period of time preceding the first weighing of the sweating sugar. In addition, it must be borne in mind that, in investigating the very method of studying this question and in striving for a general characterization of a process developing in an unknown way, what appears essential is not so much the absolute magnitude of the moistening as its relative changes over time.

Thus, with regard to the latter possibility, the necessity of repeated weighings in no way diminishes the suitability of the given method, although quantitatively it does not give absolutely exact values.

The results of the experiments carried out in the indicated direction are presented in Tables 5 and 6 below.

Here it should be noted that the values given in Table 5 for the gain or loss in the weight of the sugar, expressed in weight percent of it and referred to 100 sq. cm of the surface of the moistening cube, are hereafter taken as the expression of the “degree of moistening” or the “degree of drying of the sugar.”

One of the essential aspects of the process of moistening of sugar, regarded as the result of a definite temperature relation between the sugar and the surrounding air, is the duration of this phenomenon. Certain indications in this direction are given by the table. The results of the experiments presented here definitely show that the period of moistening of sugar, i.e., the duration of the enrichment by dew deposited upon it, proves to be extremely short—namely, from three (experiment No. 25) to 23 minutes (experiment No. 47); in the majority of the cases considered it fluctuates from 5 to 10 minutes.

If, moreover, one takes into account that the moment of the first weighing of the sugar after placing it in the chamber was usually carried out with some delay, i.e., already during the period of drying that had begun, it will become evident that the duration of moistening in reality proves to be still less than was established above. That such a delay in weighing actually occurred in many of the experiments carried out in this work can be seen from the following comparison of experiment No. 56 with experiment No. 57, and also of experiment No. 76 with No. 75. Each experiment in such a pair is almost identical with the other in its conditions and in the mass of sugar. But in the absolute quantity of dew that fell on the sugar a difference is observed. Moreover, the sugar that had moistened for a shorter time proves to be the less moistened—namely, 10 minutes. This is observed in both cases considered. And the sugar that moistened for only 5 minutes shows greater moistening in the sense of the absolute quantity of retained moisture. Obviously, the causes of this phenomenon lie in the fact that after five minutes of intensive moistening of the sugar, during the next five minutes drying of the sugar already sets in. Therefore experiments No. 56 and 57, and also No. 66 and 75, which gave unequal final moistening in absolute quantity, in reality moistened in exactly the same way. Thus, the results of these experiments too confirm the short duration of the moistening of sugar, indicating at the same time that equal masses of sugar under identical conditions moisten equally, and at one and the same time.

The short duration of the process of moistening of sugar is revealed especially clearly by experiments Nos. 71, 78, 106, 108, and 118. Here, judging by the results of the experiments, the period of moistening is supposedly completely absent. However, on carefully examining these experiments, it is easy to convince oneself that the sweating of sugar under the temperature and humidity conditions present here should have been in

TABLES

No. of experiments	Cube characteristics: length of cube edge, cm	Cube characteristics: size of cube surface	Cube characteristics: weight of sugar cube before the experiment	Duration between two adjacent weighings, min	Duration of the warming period, min	Experimental conditions—temperatures, °C: surrounding sugar	Experimental conditions—temperatures, °C: chamber	Experimental conditions—temperatures, °C: difference between the temperature of the sugar and the chamber	Experimental conditions—temperatures, °C: growing point
21	4	96	76.0641	15 20 20 30 30 40 20 35	15	0.5	18	17.5	14.5
22	4	96	76.0805	10 10 5 17 13 15	10	0	35	35	23.3
23	4	96	76.0751	5 10 20 25 10	5	0	20.5	20.5	16.3
24	4	96	76.0820	15 15 15 15 50 25 15	15	−5	19	24	[[unclear: value begins with 16.]]
25	4	96	76.1245	3 7 10 30 45	3	−1	26	27	21.1
26	4	96	76.1210	10 10 20 22	10	5	28	23	21.5
27	4	96	76.1225	4 9 9	4	4	21	17	16

Ц А 5

O B	Chamber humidity — absolute	Chamber humidity — relative, in %	CHANGE IN THE WEIGHT OF SUGAR — Gain in the weight of sugar, in grams	Gain, in % of the entire cube of sugar	Gain, in % per 100 cm²	Loss in the weight of sugar, in grams	Loss, in % of the entire cube of sugar	Loss, in % per 100 cm²	Weight of the cube of sugar after the experiment
	12.2	80 90 90 90 85 85 90 90	0.0874	0.114	0.091	0.0190 0.0150 0.0128 0.0084 0.0055 0.0030 0.0035	0.025 0.019 0.016 0.011 0.007 0.004 0.004	0.019 0.016 0.013 0.009 0.006 0.003 0.014	76.0751
	21.3	60 60 60 60 60 40	0.0535	0.070	0.055	0.0190 0.0092 0.0122 0.0074 0.0042	0.025 0.012 0.016 0.010 0.006	0.020 0.009 0.012 0.008 0.004	76.0820
	13.8	77 81 88 81 81	0.0449	0.059		0.0100 0.0200 0.0660 0.0035	0.013 0.021 0.009 0.004	—	76.0805
	13.8	85.5 85.5 85.5 90 90 90 90	0.1225	0.147	0.123	0.0810 0.0419 0.0115 0.0137 0.0044 0.0014	0.011 0.055 0.015 0.018 0.006 0.002	0.008 0.043 0.012 0.014 0.005 0.002	76.1245
	18.1	72.5 72.5 72.5 76 76	0.0585	0.076	0.061	0.0065 0.0217 0.0224 0.0114	0.009 0.028 0.021 0.015	0.007 0.022 0.023 0.012	76.1210
	19.1	64 64 64 64	0.0405	0.053	0.042	0.0230 0.0105 0.0055	0.030 0.014 0.007	0.024 0.011 0.006	76.1225
	13.5	73 73 73	0.0115	0.015	0.007	0.006 0.0098	0.008 0.013	0.006 0.010	76.1252

Experiment No.	Edge length of cube, cm	Surface area of cube	Weight of sugar cube before experiment	Duration between adjacent moistening and blowing, min	Duration of moisture removal, min	Cooled sugar, °C	Chamber, °C	Difference between temperatures of sugar and chamber, °C	Dew point, °C
28	4	96	76.1252	5 15 15 15 20 20 40	20	2.5	28	25.5	24.1
29	4	96	76.1633	5 8	5	4	19	15	13.7
30	4	96	76.1695	0 5	5	7	18.5	11.5	15.8
31	5	150	150.4381	5 15 25 40 30	20	0	18	18	14.5
33	5	150	150.4660	10 15 15 15 50 25 15	25	−5	19	24	16.4
34	5	150	150.5300	5 10 10 35 40	15	−1	26	27	21.1
35	5	150	150.5980	4 5 20 25	4	5	28	23	21.5
36	5	150	150.5600	8 7 14 6	8	4.5	21	16.5	16

Chamber humidity: absolute	Chamber humidity: relative	Sugar weight gain: in grams	Sugar weight gain: as % of the weight of the sugar cube	Sugar weight gain: % per 100 cm²	Sugar weight loss: in grams	Sugar weight loss: as % of the weight of the sugar cube	Sugar weight loss: % per 100 cm²	Weight of the sugar cube after the experiment
22.3	84	0.0968	0.127	0.101				76.1633
22.3	84	0.0040	0.005	0.004				76.1633
22.3	84				0.0396	0.052	0.041	76.1633
22.3	83				0.0124	0.016	0.013	76.1633
22.3	83				0.0035	0.005	0.004	76.1633
22.3	83				0.0030	0.004	0.003	76.1633
22.3	83				0.0042	0.006	0.004	76.1633
11.7	72	0.0167	0.022	0.017				76.1695
11.7	72				0.0105	0.014	0.011	76.1695
13.1	66	0.0072	0.009	—				76.1600
13.1	66				0.0055	0.005	—	76.1600
12.2	80	0.0619	0.041	0.041				150.4396
12.2	85	0.0100	0.006	0.007				150.4396
12.2	90				0.0374	0.025	0.025	150.4396
12.2	80				0.0276	0.017	0.019	150.4396
12.2	80.5				0.0054	0.004	0.040	150.4396
13.8	85.5	0.01470	0.117	0.098				150.5300
13.8	85.5	0.0296	—	0.019				150.5300
13.8	85.5				0.0196	0.013	0.013	150.5300
13.8	90				0.0250	0.017	0.017	150.5300
13.8	90				0.0452	0.029	0.029	150.5300
13.8	90				0.0148	0.010	0.010	150.5300
13.8	90				0.0100	0.007	0.007	150.5300
18.1	72.5	0.1538	0.102	0.100				150.5630
18.1	72.5	0.0002	—	—				150.5630
18.1	72.5				0.0380	0.025	0.025	150.5630
18.1	76				0.0515	0.034	0.034	150.5630
18.1	76				0.0315	0.021	0.021	150.5630
19.1	64	0.0520	0.034	0.035				150.5680
19.1	64				0.0040	0.003	0.003	150.5680
19.1	64				0.0318	0.021	0.021	150.5680
19.1	64				0.0192	0.013	0.013	150.5680
13.5	73	0.0800	0.053	0.053				150.5988
13.5	73				0.0395	0.026	0.026	150.5988
13.5	73				0.0117	0.008	0.008	150.5988
13.5	73							150.5988

Experiment No.	Edge length of cube, cm	Surface area of cube	Weight of sugar cube before experiments	Duration of wetting and draining, min	Duration of rest period, min	Cooling of sugar	Chamber	Difference between temperatures of sugar and chamber	Dew point
37	5	150	150.5980	5 15 15 15 20 25 35	20	2.5	28	25.5	24.1
38	5	150	150.6665	7 13	7	4	19	15	13.7
39	5	150	150.6950	10 10	10	8.5	19	10.5	15.4
44	3	54	36.7138	7 13 60	7	5	22	17	21.7
47	3	54	36.7325	23 7	23	3	20	17	14.9
54	4	96	81.9710	14 20	14	2	22	20	18.8
56	4	96	80.2614	5 15 15 15 30 30	5	0	30	30	21.6
57	4	96	80.3109	10 50	10	1.5	33	31.5	24.9
60	4	96	80.3775	5 10 25 30	5	5	22	17	21.7
65	3	54	37.5260	15 12 33 35 20	15	−2	19	21	17.4

Absolute	Relative, %	Weight gain of sugar, g	Weight gain of sugar, % by total weight of the sugar cube	Weight gain of sugar, % per 100 cm²	Weight loss of sugar, g	Weight loss of sugar, % by total weight of the sugar cube	Weight loss of sugar, % per 100 cm²	Weight of the sugar cube after the experiments
22.3	84 84 84 83 83 83 83	0.1812 0.0125	0.120 0.008	0.121 0.000	0.0415 0.0298 0.0172 0.0180 0.0191	0.027 0.019 0.011 0.012 0.013	0.028 0.019 0.011 0.012 0.013	150.6666
11.7	72 77.5	0.0484	0.032	0.032	0.0200	0.013	0.013	150.6950
14	85.5 85.5	0.0130	0.009	—	0.0095	0.006	—	150.3985
19.3	95.5	0.0267	0.072	0.049	0.0135 0.0050	0.037 0.015	0.025 0.010	36.7214
12.6	72 72	0.0235	0.064	—	0.0060	0.0016	—	—
16.2	82 82	0.0610	0.074	0.063	0.0395	0.047	0.040	81.9935
23.5	63 65.5 66 66 61 61	0.1336	0.166	0.139	0.0150 0.0290 0.0130 0.0160 0.0111	0.019 0.036 0.017 0.019 0.014	0.014 0.030 0.035 0.017 0.012	80.3109
23.4	66 66	0.1291	0.160	0.134	0.1654	0.034	0.068	80.3746
19.3	95.5 95.5 91.0 91.0	0.0535	0.066	0.056	0.0130 0.0166 0.0079	0.016 0.021 0.010	0.013 0.017 0.008	80.3935
14.8	90 90 90 90 90	0.0645	0.171	0.119	0.0090 0.0133 0.0162 0.0074	0.024 0.035 0.017 0.019	0.017 0.025 0.011 0.016	37.5536

No. of experiments	Cube edge length in cm	Surface area of cube	Weight of sugar cube before experiments	Air jet through the neighboring suspension, in min.	Duration of the experiment, in min.	Cooling of the sugar	Chamber	Difference between the temperature of the sugar and the chamber	Dew point
66	3	54	37.5536	5 10 20 20 23	5	4.5	32	27.5	23.3
71	3	54	37.5250	10	—	9.5	18	8.5	14.5
75	3	54	34.8840	10 7 20 22 20	10	4.5	32	37.5	23.3
77	3	54	34.8757	8 8	8	2.5	18.5	16	15.8
78	3	54	34.8945	8 15	—	−0.5	21.5	22	17.1
80	3	54	34.8710	5 7	5	9.5	18	8.5	14.5
81	3	54	34.8675	3	—	9	21	12	19.1
84	3	54	36.6336	20 15 15	20	0	19.5	19.5	17.9
106	3	54	35.6280	5	—	10	26	16	19.8
108	3	54	35.6265	5	—	9.5	18	8.5	14.5
112	2	24	9.0534	8 16	8	2	22	20	18.8
117	2	24	10.6632	5	—	7.5	19	11.5	13.6
118	2	24	10.6665	8	8	4.5	17.5	13	12.6

Absolute chamber humidity	Relative chamber humidity, in %	Increase in sugar weight, in grams	Increase in sugar weight, in % by weight of the sugar cube	Increase in sugar weight, in % per 100 sq. cm	Decrease in sugar weight, in grams	Decrease in sugar weight, in % by weight of the sugar cube	Decrease in sugar weight, in % per 100 sq. cm	Weight of the sugar cube after the experiments
21.3	60 60 60 50 50	0.0264	0.070	0.047	0.0125 0.0075 0.0030 0.0030	0.032 0.020 0.008 0.008	0.023 0.019 0.006 0.006	37.5540
12.2	80 80	—	—	—	0.0115	0.031	—	37.5135
21.3	60 60 50 50	0.0260	0.075	0.048	0.0180 0.0072 0.0048 0.0030	0.051 0.02 0.014 0.009	0.033 0.013 0.007 0.006	34.8770
13.5	85.5	0.0843	0.240	0.156	0.0665	0.190	0.12	34.8750
14.5	77 78	—	—	—	0.0065 0.0130	0.017 0.037	0.012 0.021	34.8750
12.2	80	0.0065	0.019	—	0.0100	0.030	—	33.8675
16.4	86.5	—	—	—	0.0075	0.021	—	34.8600
15.2	90.5 90.5 90.5	0.0649	0.177	0.120	0.0135 0.0065	0.0368 0.018	0.025 0.012	36.6785
17.4	69	—	—	—	0.0010	0.003	—	35.6270
12.2	80	—	—	—	0.0050	0.014	—	35.6265
16.2	82	0.0086	—	—	0.0055	—	—	—
13.2	81	—	—	—	0.0055	—	—	—
10.9	71	0.0005	—	—	—	—	—	—

TABLE 6

Experiment No.	Length of sugar-cube edge, cm	Surface area of sugar cube, sq. cm	Weight of sugar cube before experiment	Intervals between two adjacent weighings, h and min	Temperature, °C: lower paraffin	Temperature, °C: chamber	Temperature, °C: dew point of the air in the chamber	Relative humidity of the chamber, %	Increase in sugar weight, g	Increase in % of sugar-cube weight	Decrease in sugar weight, g	Decrease in % of sugar-cube weight	Weight of sugar cube after the experiment
1	4	96	76.0797	4—15 m.	−11	19.5	30.5—	44	0.0015	0.001	0.0049	0.005	76.0763
3	»	»	76.0763	2—50 2—25 2—40	−10	20	30—	40	0.0057 — —	0.007 — —	0.0068 0.0030	0.007 0.003	76.0732
5	5	150	150.4531	2—28 3—2	−11	19.5	30.5—	44	0.0045	0.003	0.0064	0.004	150.4512
7	11	11	150.4420	—7 —45 —5 3—15 1—30	6	19	13—	40	0.0052	0.003	0.0054 0.0080 0.0022 0.0007	0.004 0.001 0.001	150.4386
14	4	96	80.2650	—12 1—15 3—15 1—15	6	19	13—	40 » » 31	0.005	0.001	0.0129 0.0008 0.0009	0.004 0.001	80.2614

in most of these cases to manifest itself quite clearly. If, however, this is not established by the experiments, then the reason for this must be sought in an excessively great delay of the first weighing. Under such conditions, owing to drying that begins immediately after the sugar has sweated, by the moment of the first weighing after being placed in the chamber it does not increase its weight on account of the dew that has fallen on it, since by that time it has already managed to lose it, often together with part of its own initial moisture, which leads to a decrease in the original weight of the sugar.

From experiments Nos. 28, 31, and 37 it is evident that intensive sweating occurs only in the first minutes after the sugar is introduced into the thermostat chamber, which does not contradict the observations and conclusions made earlier.

Approaching the data of Table 5 from the standpoint of the absolute magnitude of the observed sweating, one may note in many experiments that considerable sweating is associated with an increase in the duration of the process itself, which is confirmed by experiments Nos. 24, 33, 34, 65, and others. However, alongside this there are also cases that contradict the indicated proposition; thus, for example, in experiments Nos. 36, 77, and No. 56 the absolute magnitudes of sweating are respectively equal to 0.0800, 0.0843, and 0.1336, whereas the corresponding times are expressed as 8.8 and 5 minutes, i.e. the case of experiment No. 56, with greater sweating, proceeds considerably faster than the case with lesser sweating.

It follows from this that the amount of thawing is not the decisive factor in the duration of this process.

In connection with this, the question arises of the influence on the duration of the thawing of sugar of its mass, its surface, the humidity of the air surrounding the sugar, and so forth. The first question may be answered by comparing the results of experiments No. 28 and No. 37. Their conditions are identical, the duration of thawing is the same, but the masses of sugar taken are different, as are their surfaces. At the same time it turns out that the thawing, expressed in absolute quantities, is different in the two cases, namely 0.1008 g for experiment No. 28 and 0.1937 g for experiment No. 37. The case considered indicates that the duration of thawing of sugar does not depend on its mass or on its surface.

In Table 5 one can find several further comparisons of individual experiments which, by their results, would seem to contradict the proposition advanced above. These include experiments Nos. 26 and 35, as well as Nos. 29 and 38, or Nos. 24 and 33, etc. Here, however, it must be borne in mind that most of them are not quite identical with one another either in their conditions, or in the duration of thawing, or in the magnitude of the latter, in the mass of sugar, etc. This circumstance makes it impossible to draw direct conclusions from a straightforward comparison of the data of such experiments. If, however, the indicated circumstance is taken into account and, for each such pair of experiments, the entire set of their conditions and of the results obtained is compared and analyzed in detail, relating the amounts of thawing and drying over separate intervals of time to their duration, then all the indicated experiments will likewise lead to confirmation of the proposition that the duration of thawing depends neither on the mass nor on the size of the surface of the sugar being thawed.

In the preceding discussion it was already established that the duration of the process of thawing, independently of the mass and surface of the sugar, remains unchanged under identical conditions of the temperature of the sugar, the temperature of the surrounding air (in the present experiments—the chamber), and the humidity of the latter. It remains further to determine the dependence of the duration of the process of sugar thawing on changes in the indicated conditions.

Considering the data of the table from this standpoint, it is not difficult to notice that high humidity in the chamber, independently of the temperature of the latter, prolongs the process of sugar thawing. This follows from a comparison of experiments Nos. 21, 28, 43, and 37 with the other experiments in which the humidity of the chamber was appreciably lower. Apparently, the temperature of the sugar also has a certain significance in this case. To clarify this question, let us compare, on the one hand, experiments with sugar having a low temperature, for example Nos. 24, 33, 65, and 84, and, on the other hand, experiments in which the sugar, before being placed in the chamber, had been heated relatively high, as, for example, in experiments Nos. 27, 29, 35, 44, 65, 80, and others. From this comparison it follows that the duration of thawing of sugar cooled below 0° is considerably longer than for sugar of a higher temperature. In addition, it may be noted that when there is a large difference between the temperatures of the sugar and the chamber, the duration of the thawing process increases. Where this is not the case, the relative humidity of the air has the predominant significance.

Summing up what has been said on the question of the duration of the process of thawing of sugar in connection with one or another set of conditions, the following propositions should be noted:

1. The thawing of sugar is a very short-lived process, usually ending within a few minutes, after which, under the continuing external conditions of temperature and humidity of the surrounding air, drying of the sugar begins.

2. The effect of sugar thawing is manifested most strongly in the first moments of its development.

1. The surface area and mass of the sugar have no influence on the duration of the sweating process.

2. The duration of the sweating process is the more considerable, the higher the relative humidity of the air, the greater the temperature difference between the sugar and the air, and the lower the temperature of the sugar.

Turning to consideration of the data of Table 6, the following should be noted. Here are grouped experiments that had an orienting significance in the sense of feeling out the very method of work, while there was as yet insufficient familiarity with the phenomenon under study itself. Therefore a certain incompleteness and irregularity resulted in the conduct of the experiments of this group. Thus, for example, not having an idea of the short duration of the unfolding of the process of sugar sweating, in the initial group of experiments there was a tendency to allot, where possible, more time for the sweating of the cooled sugar. As a result of this, at the beginning of the work it was quite impossible to establish the phenomenon of sweating and to catch it in time. This was aided not a little by the low humidity of the air surrounding the sugar.

Despite this circumstance and a certain incompleteness of the initial experiments placed in Table 6, they nevertheless are of definite interest as material illuminating the unfolding of the subsequent process of the drying of sugar. A characteristic feature of these experiments is that, in contrast to the experiments of Table 5, they were carried out under conditions of very low air humidity and substantial cooling of the sugar.

The data of the table, judging from experiments Nos. 1, 3, 5, 7, and 14, indicate that sweating of sugar can also occur under conditions of very low, down to 40–44%, relative humidity of the surrounding air, at its temperature of 19–20°C and with cooling of the sugar to −11°C. In other experiments the phenomenon of sweating was not established experimentally; however, it is possible that in isolated cases it occurred here as well.

With regard to the drying of sugar, the data of the already preliminary experiments indicate that this process too, with free contact of the sugar with the air, proceeds rather rapidly, but nevertheless considerably more slowly than sweating, requiring not minutes but hours even under favorable conditions, for example, at very low humidity of the air surrounding the sugar. With a decrease in the moisture content of the sugar, the rate of its drying slows down exceedingly.

The main conclusion: the low relative humidity of the air surrounding cold sugar does not exclude the possibility of its sweating.

Let us now turn to clarifying the dependence of the degree of sugar sweating on air humidity, on the magnitude of the temperature difference between the sugar and the air surrounding it, on the height of the dew point, etc. To clarify the above, let us compare certain data from experiments Nos. 21 and 24, presented in the following table. The conditions of these experiments are sufficiently close to one another for the possibility of comparing them.

TABLE 7.

Experiment No.	Time between weighing in minutes	Temperature in °C: sugar	Temperature in °C: chamber	Temperature in °C: difference T—p	Humidity in chamber: absolute	Humidity in chamber: relative	Dew point °C	Gain in weight of sugar in grams	Degree of sugar sweating (in wt. %) per 100 sq. cm of sugar surface
21	15	+0.5°	18.0°	17.5°	12.2	80.0	14.5°	0.0874	0.091
24	15	−5.0°	19.0°	24.0°	13.8	85.5	16.4°	0.1225	0.123

From the comparison presented, it is evident that with an increase in the absolute and relative humidity in the chamber, with a rise in the dew-point temperature, with an increase in the temperature difference between the sugar and the chamber, and with a simultaneous lowering of the sugar temperature, the degree of its moistening increases.

Let us make several more comparisons of individual experiments, set out in the following table.

TABLE 8.

No. of experiments	Time between weighings in minutes	Temperatures in °C: sugar	Temperatures in °C: chamber	Temperatures in °C: difference t − p	Humidity in the chamber: absolute	Humidity in the chamber: relative	Dew point °C	Increase in weight of sugar in grams	Degree of moistening of sugar (in wt. %) per 100 sq. cm of sugar surface
23	5	0.0°	20.5°	20.5°	13.8	77	16.3°	0.0446	0.060
25	3	−1.0°	26.0	27.0	18.1	72.5	21.1	0.0385	0.061
27	4	−4.0	21.0	17.0	13.5	73	16.0	0.0115	0.007
28	5	2.5	28.0	25.5	22.3	84	24.1	0.0968	0.101
30	5	7.0	18.5	11.5	13.4	66	15.8	0.0072	0.009
22	10	0.0	35.0	35.0	21.3	60	23.3	0.0535	0.055
26	10	5.0	28	23.0	19.1	64	21.5	0.0405	0.042

Comparing the data of the first five experiments of this group, we see that the highest degree of moistening corresponds to experiment No. 28, characterized by high absolute and relative humidity of the chamber, a considerable temperature difference between the sugar and the chamber, and a high sugar temperature equal to 25°C. A somewhat smaller degree of moistening corresponds to experiment No. 25. Here, in comparison with the preceding case, the humidity is somewhat lower and all the other factors are present, but the temperature difference between the chamber and the sugar is greater.

Proceeding further in the order of decreasing degree of moistening (experiments Nos. 23, 27, and 30), we see that this decrease is caused by a gradual lowering of the humidity of the chamber, as well as by a diminution of the temperature difference between the sugar and the chamber.

From a comparison of the data of experiments Nos. 22 and 26 it is evident that, with the same duration of the process and sufficiently close humidity conditions, the degree of moistening is noticeably higher in experiment No. 22, which is due to the greater temperature difference between the sugar and the chamber and to the lower temperature of the sugar.

A comparison of the results of experiments Nos. 27 and 30 also confirms the dependence of the degree of moistening on the temperatures of the sugar and the chamber and on the humidity of the latter.

From the data of experiments Nos. 33 and 39, where the masses of sugar are the same and the other conditions, apart from the temperature of the sugar, are sufficiently close to one another, it follows that colder sugar moistens more strongly.

Experiments Nos. 35 and 37 confirm the proposition that the degree of moistening increases with an increase in the absolute and relative humidity of the air surrounding the sugar, other conditions being equal.

All that has been set forth above concerning the dependence of the degree of sweating of sugar on the humidity of the air, its temperature and that of the sugar, and the temperature difference between them leads to the following proposition:

The degree of sweating of sugar increases:

1) with an increase in the absolute and relative humidity of the air surrounding the sugar;

2) with an increase in the temperature difference between the sugar and the air surrounding it;

3) with a lowering of the temperature of the sugar.

Let us now turn to establishing, in the sweating of sugar, the dependence between its mass and the quantity of moisture, in units of weight, condensing upon it. We shall call this the “absolute quantity of moisture” deposited on the sugar, and shall hereafter adhere to this designation, in distinction from the “relative quantity,” expressed as a percentage of the weight of the sugar.

It is obvious that the solution of the question posed includes a definite ratio between the mass of the sweating sugar and its surface, which receives upon itself the moisture condensing from the air. When this ratio changes, naturally, the quantitative effect of sweating also changes.

The surface of sugar, whether sand or refined sugar, consists of an internal and an external surface. The former, bounding the intercrystalline spaces, is many times greater than the latter. Nevertheless, in the process of sweating of sugar, its external surface is of principal importance, since it is chiefly along it that free contact occurs between the sugar and the air surrounding it. Of course, the latter is in direct contact, through the pores of the sugar, also with the air of the intercrystalline space. However, capillarity impedes free communication and mixing of the external air with the air of the intercrystalline space, reducing the possibility of sweating of the sugar within its mass, which in the preceding exposition has already been examined in its proper place.

In addition, under the influence of the molasses present in the sugar, under certain conditions there may occur the filling by it of the outer pores of the sugar and, consequently, to a certain extent, the isolation of the internal surface of the sugar from contact with the external air. Thus, when speaking of the sweating of sugar, one should reckon chiefly with the external surface of the sugar. If this proposition is accepted, then, in considering the question posed, one must maintain a definite ratio between the external surface and the mass in the sugar subjected to sweating. In view of this, in the present work all experiments were conducted with refined sugar taken in the form of regular cubes, which must be borne in mind both when considering the question in the present case and when assessing the conclusions thereby obtained in general.

Passing to the actual consideration of the dependence between the absolute quantity of dew released and the mass of the sweating sugar, let us compare two experiments, identical in conditions but different in the masses of sugar, Nos. 25 and 34.

It then turns out that the absolute quantity of dew deposited on the larger mass of sugar is greater than on the smaller. With the ratio of the masses of sugar equal to \(76 : 150\), the ratio of the quantities of dew that fell corresponds to \(0.0585 : 0.1538\). Thus, the larger mass corresponds to the larger absolute quantity of dew released. This proposition can be confirmed by a number of other comparisons, for example, by experiments Nos. 28 and 37, or Nos. 29 and 38, etc.

In order to present this proposition more clearly, below is given a table containing experiments close in conditions but different in the masses of the sweating sugar, selected in such a way that in pairs they are entirely identical with respect to conditions.

TABLE 9.

Experiment No.	Weight in grams	Surface area in sq. cm	Relative humidity in the chamber	Temperature, °C: sugar	Temperature, °C: chamber	Change in weight of sugar after sweating: in grams	Change in weight of sugar after sweating: % by weight of sugar	Degree of sweating of sugar: in weight % per 100 sq. cm of surface	Degree of sweating of sugar: in grams per 1000 g of sugar
54	81.97	96	82%	2°	22°	0.0610	0.074	0.071	7.4
112	9.05	24	82	2	22	0.0086	0.095	0.396	9.5
60	80.38	96	95.5%	5°	22°	0.0535	0.066	0.069	6.6
44	36.71	54	95.5	5	22	0.0267	0.072	0.152	7.2
35	150.56	150	64	5	28	0.0520	0.034	0.023	3.4
26	76.12	96	64	5	28	0.0115	0.053	0.053	5.3

From the comparison presented, the proposition clearly emerges that larger masses of sweating sugar correspond also to a greater absolute quantity of dew released upon them. The amount of it falling per unit of weight, for example per 1000 g of sugar, is relatively greater for smaller masses of sweating sugar. This increase in the degree of sweating with a decrease in mass is still more sharply reflected with respect to the surface of the sugar.

In experiments No. 35 and No. 26, with a ratio of sugar masses of 150:76, i.e. about 2:1, the ratio of the quantities of dew deposited per 100 sq. cm of surface is 0.023:0.054, i.e. about 1:2. The influence of mass is especially pronounced in experiments No. 54 and No. 112. Here, with a mass ratio of 81.97:9.05, or simply 9:1, the ratio of the degree of sweating of the outer surface of the sugar is 0.074:0.396, or 1:5.

This proposition is extremely important for deciding how sugar should be stacked in order to protect it from sweating if it is dry, and what its stacking should be in the case of excess moisture in it, since the process of drying of sugar proceeds in the reverse order to the process of sweating.

Thus, larger masses of sweating sugar correspond also to a greater absolute quantity of dew released upon them, while smaller masses correspond to a greater degree of sweating, especially of their outer surface.

If some experiments are encountered that appear not to follow the indicated regularity, the reasons for this lie either in the accompanying circumstances—for example, in the occurrence, during the cooling of the sugar, of some drying of it, etc.—or in the fact that the influence of the mass of sugar in individual cases is suppressed by the stronger influences of other factors.

The results of experiments with equal or very nearly equal masses of sugar, for example in No. 112 and No. 117, indicate that, with equal masses and under identical sweating conditions, equal quantities of dew are released.

What has been set forth above leads to the following propositions:

1. Under otherwise identical conditions of sweating, the absolute quantities of moisture condensing on sugar are greater for its larger masses.

1. With a decrease in the monolithic mass of the drying sugar there is associated a relative increase, per unit mass, in the absolute amount of moisture released thereby.

All experiments on the drying of sugar were invariably accompanied by its subsequent drying out. Without entering into a detailed analysis of this phenomenon, we shall briefly note here the most characteristic features of this phenomenon and the conditions of its development.

The data of all the experiments definitely indicate that the process of drying out is revealed immediately after the end of the drying. It manifests itself under the very same external conditions of temperature and humidity under which the preceding drying of the sugar took place.

Drying out is most strongly expressed in the first period of time after the end of drying. Thereafter the intensity of this process gradually falls, slowing down extremely with the passage of time. Looking through the results of the experiments carried out, one can easily notice that the drying out of sugar increases with a decrease in the humidity of the air surrounding the sugar. The increase in the temperature difference between the sugar and the air contributes to the same effect.

An increase in the external surface of the sugar, all other conditions being identical, leads to an increase in the degree of drying out.

Low temperature does not exclude the possibility of sugar drying out.

The drying out of sugar proceeds considerably more slowly than its drying. And if the drying of sugar takes place in several minutes, then for the removal of the absorbed water, in the best case, hours of desiccation are required.

This proposition is of great importance in the matter of storing sugar in warehouses, as well as with respect to the servicing of the latter. The persistent and invariably recommended ventilation of warehouses, widely applied in practice without taking this proposition into account, not infrequently gravely violates the interests of the stored sugar.

Concluding the analysis of the results of the experimental part of the work, it is not without interest to note certain external changes in sugar in connection with its repeated drying and subsequent drying out. The initial refined sugar had a moisture content of 0.10–0.15% by weight. After 2–3 months of work the average moisture of the samples taken fluctuated around 0.66%. Thus, despite the short duration of the drying operations, when they were repeated up to 15–20 times and more for an individual piece, the moisture content of the sugar rose to 0.5% and higher. After 6–10 cases of drying, depending on its degree, the tested cube of refined sugar changed noticeably on the outside. It became glossy and was covered as if with a layer of transparent enamel. This phenomenon persisted subsequently to the end of the experiments. When such a dried cube of refined sugar was split, an outer, darker layer 2–3 millimeters thick was found in it. The outer layer is a mass of sucrose crystals ordinary for refined sugar, the space between which is filled with a sugar solution, which in turn has crystallized in small transparent crystals. The inner thickness of the refined-sugar sample at the fracture has the appearance of sugar that has plainly dried, but is lighter than in the outer layer of the tested cube of sugar. The general appearance of the fracture of the dried cube indicates the nonuniformity of the drying of the sugar in the transition from the surface toward the middle. Since drying in varying degrees usually entails an unequal change in the sugar, and in particular the formation in it of reducing substances, the idea therefore arose of tracing the change in the degree of drying of the sugar in the various layers of the experimental cube of refined sugar by the amount of reducing substances formed in it at different depths of its thickness. To carry out this task the following method of work was used: the experimental cube of refined sugar was sawn with the blade of an ordinary fret saw into layers 2–3 mm thick, in order of transition from the surface of the cube into its depth. From the sawn layers of refined sugar...

medium samples were obtained, which were examined by Bertrand’s method for reducing substances, then recalculated as invert sugar.

The results of testing several dried-out cubes at various depths from their surface are presented in the following table, which gives: the dimensions of an individual cube, expressed by the size of its edge in centimeters, and the content of reducing substances, expressed as invert sugar and recalculated as a percentage by weight in the original dry sugar.

TABLE 10.

No. of cube	Edge of cube, cm	Content of reducing substances in % by weight of sugar: in the original refined sugar	Content of reducing substances in % by weight of sugar: after drying, in the surface layer of 3 mm	Content of reducing substances in % by weight of sugar: after drying, at a depth from the surface, 5 mm	Content of reducing substances in % by weight of sugar: after drying, at a depth from the surface, 10 mm	Content of reducing substances in % by weight of sugar: after drying, at a depth from the surface, 18–20 mm	Content of reducing substances in % by weight of sugar: after drying, at a depth from the surface, 23–25 mm
1	5	Traces . . . . .	0.35%	0.68%	0.48%	—	0.34%
2	4	” . . . . .	0.45%	0.60%	—	0.52%	—
3	4	” . . . . .	0.33%	0.42%	0.43%	0.31%	—

From the above it is evident that the amount of reducing substances, and consequently also the drying-out of the sugar as one passes from its outer surface inward, gradually increases, but from a certain depth it begins again to decrease, so that, with a cube edge of 4–5 cm, the central part of the sugar proves less rich in reducing substances than the layers lying closer to the outer surface, in the cases considered at 10 mm from it. The reason for this is clear; to a certain extent it is also suggested by the external appearance of the fracture of the dried-out sugar. In the surface, vitrified layer, which is drier, decomposition of the dried-out sugar proceeds more slowly than in the inner, moister layers. At the same time, it is obvious that the closer a layer is to the outer surface, the greater opportunity it has for drying, and therefore the amount of reducing substances in it is smaller in comparison with the more deeply lying layers of sugar. The decrease in the amount of reducing substances in the central part of the cubes, however, is a consequence of the lower moisture of this region owing to obstacles that hinder the spread of drying into the thickness of the sugar and that increase with distance from the outer surface of the sugar.

Thus, with respect to the question of the change in sugar that has repeatedly dried out and dried under the conditions of the experiments, the following propositions become apparent:

1. The sugar in the surface layer 2–3 mm thick appears vitrified; the remaining mass is distinctly dried out throughout its entire thickness.

2. Drying-out in the outer surface layer is lower than in the subsequent layers, where the moisture gradually increases to a certain depth, after which it begins to decrease again.

It should be noted that during drying-out in warehouses, vitrification of the outer layer of sugar is usually not observed, since in warehouses the alternation of drying-out and drying does not occur as sharply as it did under the conditions of the experiments considered.

Everything set forth above, and the conclusions drawn in connection with it concerning the moistening of sugar, proceeded from an analysis of the interrelations, under definite temperature conditions, of atmospheric air and sugar.

In this, sugar was regarded as consisting of only two components, namely, pure crystalline sucrose and moist air included in its intercrystalline space. In reality, besides these two components, both in granulated sugar and in refined sugar there is still another one—namely, molasses, i.e., an aqueous concentrated solution of sucrose with a known content of nonsugars.

The quantity and quality of the latter, as well as of the molasses itself, may change considerably over time under the influence of external and internal factors. It is obvious that the molasses of sugar, being subject to all the influences that the sugar itself experiences, in turn exerts a certain effect on the air and crystalline sucrose in contact with it, over whose surface this molasses is uniformly distributed throughout the whole mass of sugar. Owing to this, in the interrelation of air with solid sugar there is in reality no direct contact. It is excluded by the layer of molasses and is replaced by the interrelation of this molasses, on the one hand, with the air, and, on the other, with the crystalline sucrose over whose surface the molasses is distributed.

This circumstance does not in the least invalidate the correctness of the conclusions previously drawn regarding the interrelation of sugar and air, since in this case the sucrose composing the mass of sugar was considered only from the standpoint of its temperature, and not of its other properties. Hence it is clear that the essence of the questions previously examined is not at all changed by the presence of molasses in the sugar, provided only that this molasses has the same temperature as the crystalline mass of the sugar.

Let us now consider the interrelation of molasses with the mass of pure crystalline sucrose.

When the temperature changes, the solubility of sucrose changes: it increases with a rise in temperature and decreases with a fall in it. Therefore, under temperature fluctuations, the presence of molasses in sugar, irrespective of all other conditions, is a means that disturbs the integrity of the sugar. On heating, a portion of the solid sucrose mass dissolves in the molasses. This increases the quantity of molasses and, as it were, intensifies the moistening of the sugar, without increasing the absolute quantity of moisture contained in it.

A lowering of the temperature should lead to the crystallization of the sugar contained in the molasses. However, this process proceeds much more slowly for many reasons—namely, because of the presence and accumulation over time of nonsugars in the molasses, because of the possibility of supersaturated solutions, etc. Thus, the presence of molasses in sugar, when temperature changes are possible, in addition to all other conditions, is a factor physically promoting the transition of sugar from the solid state into solution, independently of any increase in the quantity of moisture in the sugar.

The significance of molasses in the interrelation of sugar with air follows from the fact that all moisture deposited on sugar during its moistening is taken up only by the surface of the molasses, just as the drying of sugar is connected only with the evaporation of molasses from its surface. In both cases the concentration of the molasses changes, and this in turn leads either to the dissolution of solid crystalline sucrose or to its precipitation from solution.

What has been said indicates that, when molasses is present in sugar, the interrelation of air with sugar is inseparably connected with the simultaneous interrelation of molasses with the solid sucrose of the sugar mass. Thus, the question of the possibilities of moistening or drying sugar is reduced to determining the conditions of equilibrium of the system: solid sucrose, its saturated aqueous solution, and water vapor of the air.

V. S. Tvertsyn¹), who determined the conditions of moistening of sugar during its transport by sea to the Far East, dwells on this question; his results are given below.

Considering a system consisting of a crystal of pure sucrose and water vapor in the surrounding air, it is not difficult to see that the moistening of sugar, at the corresponding temperature differences of the sugar and the air, is possible at any humidity from 0 to 100%.

When sugar becomes moist, its dissolution at once begins in the dew deposited upon it. As a result, a solution of it appears on the solid sucrose, i.e. molasses.

The equilibrium between a solution and its vapor is completely determined by Raoult’s law. Here the relative lowering of the elasticity of the saturated vapor of the solvent when some substance is dissolved in it is equal to the ratio of the number of dissolved molecules to the number of molecules of the solvent.

The equilibrium between the sugar solution and its vapor at the same time ensures equilibrium between the sugar solution and the undissolved crystalline mass of it.

Thus, under these conditions, the solid sucrose no longer dissolves in the molasses covering it; the latter also retains its concentration, neither becoming diluted nor becoming more concentrated, i.e. it does not evaporate.

Under such conditions, the equilibrium of the entire system (sugar, its solution, and moist air) is determined by a single requirement, namely, that the elasticity of the vapors of the air must be equal to the elasticity of the vapor of the solution covering the crystalline mass of the as yet undissolved sugar. This leads to the fact that the possibility of preserving sugar without moistening or drying comes down, in the plane under consideration, to the question of determining, for a given temperature, the elasticity of the vapors of the sugar solution, i.e. of the molasses on its crystals, since by this is determined the equal elasticity of the vapors of the air at the given temperature for the sugar. Having both, it is easy to determine the corresponding humidity of the air, ensuring the possibility of preserving the sugar without moistening and drying; the expression of this is the equilibrium of the above-mentioned system.

All that has been said would give rise to no objections in the case of dilute solutions.

In the case under consideration, however, one has to deal with saturated sugar solutions, for which Raoult’s law can give only a certain approximation.

Nevertheless, in the absence of other possibilities, it seems inevitable to follow precisely this path in solving the question, since, not having firm principles for saturated solutions, it is possible by this method too to find at least general guiding conclusions that facilitate the understanding of the phenomenon under examination.

Under such conditions, to determine the elasticity of the sugar solution of the system indicated above, it is possible to make use of the well-known formula for the vapor of dilute solutions.

This formula has the following form:

\[ \frac{p_1}{p}=\frac{N}{N+n}\ldots\ldots\ldots (1) \]

where:

\[ \left\{ \begin{array}{l} p_1\text{—elasticity of the vapor of the solution.}\\ p\text{—elasticity of the vapor of the solvent.}\\ N\text{—number of molecules of the solvent.}\\ n\text{—number of molecules of the dissolved substance.} \end{array} \right. \]

¹) V. Sakh. Prom.—1915—96—167 pp.

From the formula given, we obtain the vapor pressure of the solution, \(p_1\), which is of interest to us, when the solution contains \(n\) molecules of the dissolved substance and \(N\) molecules of the solvent.

\[ p_1 = p \frac{N}{N+n} \]

Multiplying both sides of the original equation by 100, we obtain in the first part an expression of moisture in percent, or the relative humidity of the air, the numerical value of which is determined by the second part of the equation:

\[ 100 \frac{p_1}{p} = 100 \frac{N}{N+n} = \text{humidity in percent.} \]

It is evident that all the reasoning applicable to the vapor pressure of the solution, \(p_1\), is also applicable to the quantity \(100 \frac{p_1}{p}\), i.e., to the relative humidity of the air surrounding sugar. This means that the equilibrium conditions of the system considered earlier, and consequently the possibility of preserving sugar without moistening and without drying out, are expressed as follows:

the relative humidity of the air surrounding sugar must be equal to the relative humidity conditioned by a saturated sugar solution at the given temperature.

Thus, we have at our disposal an expression which approximately determines the value of the relative humidity of the air, an increase of which at a given temperature leads to the moistening of sugar. The numerical value of this limiting humidity is determined by the formula \(\frac{N}{N+n} 100\). Using this formula one can establish, for any temperature, the limiting humidity of the air up to which sugar does not become moist. For this it is only necessary to know the solubility of sugar at various temperatures in the state of saturated solutions, which is known and is presented in the table below.

TABLE 11.

Temperature °C	In 1000 cu. cm dissolves, g of sugar
0	1792
5	1847
10	1905
15	1970
20	2039
25	2114
30	2155
35	2284

Knowing that the molecular weight of water is 18, we find that one liter of water contains

\[ \frac{1000}{18} = 55.55 \]

gram-molecules of water, i.e., \(N = 55.55\). As for the number of gram-molecules of pure sucrose \(n\) contained in saturated solutions in one liter of water at various temperatures, this is determined by dividing the corresponding numbers in the table just given by the molecular weight of sucrose—342.

Thus, at \(0^\circ\), 1792 g of sucrose dissolve in 1000 cu. cm of water. Hence

\[ n = \frac{1792}{342} = 5.24 \]

gram-molecules of sucrose,

and then the limiting humidity of the air for these conditions is

\[ \frac{N}{N+n} 100 = \frac{55.55}{55.55 + 5.24} = 91.3\% \]

Calculating in a similar way, the values of the limiting humidities for sugar at various temperatures were obtained\(^1\), which are given below in the table.

\(^1\) V. Sakh. Prom. 1915, p. 168.

Here, too, the limiting humidity is given for sugar where the sucrose, having passed entirely into solution, has undergone inversion, with “\(n\)” becoming “\(2n\),” since one molecule of sucrose, upon inversion, gives two molecules of hexose.

As the sugar is inverted, a new quantity of sucrose passes into solution; this leads to the result that, in the limit, “\(n\)” reaches a value equal to three.

In view of this, the table also gives the values

\[ \frac{N}{N+n}\cdot 100 \]

TABLE 12.

Temperature, °C	Limiting relative humidity of the air, excluding the possibility of the sugar becoming damp, \(\frac{N}{N+n}\times 100\)	Limiting relative humidity of the air, excluding the possibility of the sugar becoming damp, \(\frac{N}{N+2n}\times 100\)	Limiting relative humidity of the air, excluding the possibility of the sugar becoming damp, \(\frac{N}{N+3n}\times 100\)
0°	91.3%	84.1%	77.9%
5	91.0	83.6	77.4
10	90.8	83.1	76.8
15	90.6	82.6	76.2
20	90.3	82.1	75.5
25	89.9	81.6	74.9
30	89.6	81.1	74.2
35	89.2	80.6	73.5

As is evident from the second column of the table given above, the humidity determined by a saturated solution of exceptionally chemically pure sucrose within the range from \(0^\circ\) to \(35^\circ\mathrm{C}\) varies from 91.3 to 89.2%. Obviously this is a theoretical or practically exceptional case.

Sugar produced by refineries, and still more by beet-sugar factories, usually contains in its molasses film a certain quantity of inorganic and various organic substances, such as invert sugar and the products of its decomposition and transformation. Owing to this, the more realistic case appears to be that corresponding to the condition

\[ \frac{N}{N+3n} \]

This indicates that, in practice, the limiting humidity of the air that excludes the possibility of sugar becoming damp varies, depending on temperature, from 73.5 to 77.9%.

Under conditions of appreciable dampening and staling of sugars, the limiting humidity for preventing further dampening of sugars must be still lower.

This means that, when sugar is stored in warehouses, the humidity inside them must under no circumstances fall below 73.5–77.9%; in summer it is lower, in winter higher.

As soon as the humidity of the air rises above the limiting value for the given temperature, the sugar at once begins to become damp. The process of dampening stops when so much water has fallen out of the air onto the sugar that the humidity of the air becomes equal to the humidity determined by the solutions of molasses on the sugar.

If the air surrounding the sugar is continuously renewed under these conditions (the case of intensified ventilation of the warehouse), then it is obvious that the process will not stop, but will continue until all the sugar has passed into solution.

In the absence of ventilation, under the same conditions of excessive humidity of the air, the amount of moisture that can settle on dampening sugar is limited. It is determined by the difference between the humidity of the air and the limiting humidity for the given temperature and other conditions, then by the volume of air in contact with the sugar and by their temperature.

From all that has been said, one may also conclude that purer and drier sugar becomes damp at higher humidity, i.e., it is more resistant to dampening and therefore proves more durable in comparison with less pure and relatively moist sugar. Therefore, those regions where, owing to climatic or other conditions, the sugar being sent is threatened to a greater extent by dampening should, as far as possible, be supplied with dry and high-quality sugar.

Comparing all that has been considered above, it should be noted that temperature conditions have a predominant significance in the storage of sugar in warehouses.

The significance, for the storage of sugar, of the temperature conditions and humidity of atmospheric air, given its extreme variability in this respect, makes the use of sugar warehouses in industry unavoidable.

Ideally, these warehouses should be thermostats capable of quite steadily maintaining within the warehouse space the temperatures and humidity necessary for sugar, independently of the season, weather, and generally the state of the outside air. It is obvious that this kind of task, with the enormous quantity of sugar annually produced by each factory in the short period of production, proves technically and economically inaccessible. Therefore industry makes use of cheaper and simpler warehouses, in the vast majority unheated. Their task is considerably smaller. Besides protecting sugar from rain, snow, etc., the chief purpose of such warehouses consists in softening the effect upon sugar of sharp temperature fluctuations of the atmospheric air, and thereby preventing or at least weakening the dampening of sugar connected with this.

Under these conditions it is obvious that the construction of sugar warehouses depends to a considerable degree on where the given warehouse is to be located. Naturally, the construction of a warehouse, while pursuing one and the same aim, will be very different, for example, for the island of Cuba, Northern Italy, Kharkov Province, and the city of Yakutsk. Thus, the construction of the warehouse is determined to a significant extent by local climatic conditions. But apart from the individual features connected with the geographical position of the warehouse, all sugar warehouses must have certain basic features in common, defined by their task. These follow from the fact that the warehouse is an intermediate air environment in the interaction between the stored sugar and the outside atmospheric air. Consequently, the question comes down to clarifying the relationship of sugar with the air space and to illuminating how these relationships change in connection with changes in the state of the outside air.

Having in the present case in view the question of the rational arrangement of sugar warehouses in Siberia, let us dwell on the peculiarities of the local climate. The life of Siberia, from the standpoint of the interests of storing sugar in warehouses, is chiefly concentrated within the limits of the climatic belt defined by the Siberian Railway and its comparatively short lateral southern branches. The main centers of concentration of sugar in Siberia are Chelyabinsk, Omsk, Novo-Nikolaevsk, Tomsk, Barnaul, Krasnoyarsk, Irkutsk. Climatically, all these points are sufficiently close to one another and have a common distinguishing feature, very essential for questions of sugar storage—namely, the sharply expressed continentality characteristic of Siberia in general. Of the points listed, Tomsk is characteristic, being situated farthest north and, moreover, near immense taiga expanses. Since very large quantities are usually concentrated in Tomsk—

amounts of sugar, we shall therefore turn to consideration of the climate of the city of Tomsk, as a typical point with respect to the question of storing sugar in warehouses in Siberia.

The geographical position of Tomsk¹: latitude \(56^\circ 30'\), longitude \(84^\circ 56'\); height above sea level 100–180 meters.

Mean monthly temperatures.

Month	Temperature	Month	Temperature	Period	Temperature
January	\(-19.6^\circ\mathrm{C}\)	July	\(18.7^\circ\mathrm{C}\)	Winter	\(-18.0^\circ\mathrm{C}\)
February	\(-16.8\)	August	\(15.7\)	Spring	\(-0.7\)
March	\(-9.8\)	September	\(9.4\)	Summer	\(17.0\)
April	\(0.7\)	October	\(0.3\)	Autumn	\(-0.3\)
May	\(8.5\)	November	\(-10.6\)	Year	\(-0.6\)
June	\(15.7\)	December	\(-17.5\)

From the table it is evident that the coldest month is January (\(-19.6^\circ\)), the temperature maximum is in June (\(18.7^\circ\)), and six months have a mean temperature below zero. The amplitude of the annual fluctuations of the mean monthly temperature is \(38.3^\circ\).

The greatest and least absolute temperature readings at the hours of observation over 37 years give, by month, extraordinarily large fluctuations.

Month	Highest	Lowest	Amplitude
January	\(3.8^\circ\mathrm{C}\)	\(-49.8^\circ\mathrm{C}\)	\(53.6\)
February	\(4.2\)	\(-46.1\)	\(50.3\)
March	\(9.3\)	\(-42.1\)	\(51.4\)
April	\(24.4\)	\(-26.4\)	\(50.8\)
May	\(30.3\)	\(-10.6\)	\(40.9\)
June	\(35.0\)	\(1.3\)	\(33.7\)
July	\(35.6\)	\(5.7\)	\(29.9\)
August	\(31.4\)	\(1.7\)	\(29.7\)
September	\(26.9\)	\(-8.1\)	\(35.0\)
October	\(22.1\)	\(-26.8\)	\(50.9\)
November	\(9.4\)	\(-46.7\)	\(56.1\)
December	\(2.8\)	\(-51.2\)	\(54.0\)

The magnitude of the temperature amplitude over a month ranges from \(29.7\) to \(56.1^\circ\mathrm{C}\). It is smaller in summer.

The instability of the Tomsk climate is expressed especially vividly in sharp changes of temperature when passing from one day to the immediately following day.

Below are given several examples of especially sharp changes in temperature when recording it at 7 o’clock in the morning over two immediately consecutive days.

The temperature rose:

By	During the transition	Date
\(35.6^\circ\mathrm{C}\)	from 4 to 5	December 1879
\(33.5^\circ\)	from 30 to 31	December 1895
\(26.4^\circ\)	from 13 to 14	November 1910
\(15.6^\circ\)	from 6 to 7	April 1910

Under the same conditions the temperature fell:

By	During the transition	Date
\(33.4^\circ\)	from 13 to 14	February 1879
\(29.1^\circ\)	from 19 to 20	February 1895
\(27.6^\circ\)	from 2 to 3	March 1876
\(27.2^\circ\)	from 23 to 24	March 1910
\(20.1^\circ\)	from 1 to 2	April 1879
\(29.2^\circ\)	from 14 to 15	November 1902
\(30.6^\circ\)	from 13 to 14	December 1879
\(36.9^\circ\)	from 23 to 24	December 1890

These colossal temperature jumps are especially characteristic of the Siberian climate and, at the same time, dangerous for the dampening of sugar. The onset of this phenomenon, and to a very considerable degree, falls for Tomsk, and in general for Siberia, in the months of February and March. This circumstance should be taken into account in the question of the time for dispatching sugar to Siberia.

The average humidity of the air in Tomsk is as follows:

	Abs.	Rel.		Abs.	Rel.		Abs.	Rel.
January	1.0	80%	May	5.2	62%	September	6.8	77%
February	1.1	78%	June	9.1	68%	October	3.9	79%
March	1.8	73%	July	11.7	74%	November	2.0	81%
April	3.1	67%	August	10.3	78%	December	1.2	82%

The data cited indicate that the climatic conditions of the city of Tomsk, and of Siberia in general, are very little favorable to the storage of sugar here in warehouses. At the same time, they impose high requirements on the arrangement and equipment of warehouses and on the understanding here of the nature of the care required for the sugar stored in them.

In view of the established predominant influence of temperature conditions on the processes of sugar dampening, it is expedient to carry out the analysis of the conditions of its storage in warehouses with reference to the case in which temperature influences manifest themselves most sharply. Such a case is presented by the sugar warehouse in the city of Tomsk, on which we shall dwell further when speaking of the storage of sugar in Siberia.

The temperature conditions and air humidity in a warehouse are the result of the action upon the air space of the warehouse of the outside atmospheric air, the mass of the stored sugar, and finally, to a certain extent, the ground on which the warehouse stands, if it is not located on the second floor. All these influences, both taken separately and in their aggregate, change with the passage of time. In this connection it is necessary to have an idea of the successive changes throughout the entire year in the meteorological conditions of the area of the given warehouse. Familiarity with and study of these data concerning successive changes in the temperature and humidity of the atmospheric air provide indications of the possibility and degree of dampening that threatens the sugar.

In order to give a clear idea of this without burdening oneself with a mass of figures requiring prolonged study and comparison, their graphical representation is given below in drawing I. The graph covers the whole year and includes diagrams of the successive daily changes, namely: the minimum and maximum of relative humidity and temperature for 1925; and it also gives successive changes, but already according to average monthly data, in relative and absolute humidity and temperature for the period 1885—1910.

For the question of the mass storage of sugar in the warehouses of Siberia, these diagrams are of interest only for the first half of the year, since sugar arrives at Siberian warehouses mainly during January–March, and by the end of summer or in autumn the warehouses are usually already freed of sugar.

An analysis of the data of drawing I yields a great deal that is of interest. First of all, let us dwell on humidity.

The character of the daily changes in the diagrams of relative humidity for 1925 reveals, in general, extremely large fluctuations, which is characteristic of Siberia. They become especially sharp and frequent beginning in mid-May, then continuing, although in a somewhat softened form and at a slower pace, through the months of June and July.

The greatest fluctuations are exhibited by the daily minima of relative humidity. This at times causes a considerable divergence between the mean daily humidity and its minimum. This divergence appears sharply, but for comparatively short periods, in February. Disappearing during March and having little effect in April, it appears again from mid-May, becoming already stable and considerable, especially in June. This situation persists thereafter, but with relatively short interruptions in the first half of July, mid-August, and early September.

In the following months of October and November the divergence between the mean daily humidity and the minimum, now increasing, now decreasing, gradually disappears, becoming episodic and very small in the months of November–December.

The noted fluctuations in the magnitude of the divergence between the minimum and maximum, and consequently also their divergence from the mean daily relative humidity, are, in connection with temperature changes, of very great importance with respect to the possibility of sugar becoming damp during storage. The greater the divergence, the greater the danger of sugar becoming damp. From what has been said it follows that February, the beginning of April, and the period from mid-May through July inclusive are threatening with respect to the possibility of sugar becoming damp.

Relative humidity in the most dangerous period, May–July, decreases noticeably, but this does little to improve the situation, since absolute humidity at this time increases extremely. In the months of May and June it, compared with January and February, as the diagram shows, increases 5–10 times. This indicates that possible dampening in May–July, not only in comparison with February, is great, but also in its absolute magnitude must be very considerable. In addition, in the present case it is necessary to take into account the established short duration of the process of dampening and the comparatively very great duration of the drying corresponding to it. Under the Siberian climate, when dampening is inevitably repeated, as is evident from the diagrams of drawing I, this circumstance must inevitably bring the stored sugar in the period May–July to a very high degree of dampness.

Under conditions of atmospheric air, the phenomenon of dampening is most closely connected with temperature changes. In this connection let us turn to consideration, according to drawing I, of the diagrams of daily temperature minima and maxima for 1925. From the drawing it is evident that the course of temperature changes reveals the same thing as the humidity curves. The same sharpness of transitions, the same characteristic periods, the same rapidity of changes in the corresponding seasons of the year. Complete correspondence is observed in the course of the curves for mean monthly temperatures and for absolute humidity. Both, constantly increasing, undergo a break in the middle of July. Correspondingly to this proceeds also the decrease of the curve of relative humidity according to the monthly means, but its break falls in the middle of May. In general, the course of the temperature curves of drawing I marks the periods already identified earlier: February and, chiefly, May–June, as the most dangerous with respect to the possibility of sugar becoming damp.

In considering the conditions under which sugar becomes damp, it was established that, from the quantitative side, the absolute magnitude of the difference between the air temperature and the temperature of thawing of sugar, or of the corresponding dew point for the air releasing this dew, has great significance for the results of this process.

In this connection drawing II is presented. In it are shown: one diagram of daily maxima and another diagram of the corresponding dew-point temperatures in °C, calculated from the mean daily relative humidity for Tomsk for 1925. Under such conditions the change in the magnitude of the segments of the ordinates between the lines of the mentioned diagrams, presented in the dra—

of the same II, express the relative increase or decrease in the amount of dew released at a given temperature and corresponding, according to diagram I, air humidity. In order to make it possible to represent this situation clearly and visually as a whole, without going into details, two more diagrams have been plotted on drawing II: first, the mean monthly daily temperature maxima and, second, the mean monthly temperatures of the dew points for the same year.

The divergence of these curves is observed throughout the entire year, with its smallest value, \(2^\circ\mathrm{C}\), in the months of January and December. Consequently, throughout the year the possibility of dampening invariably remains. The smallest mean monthly divergence of temperatures in December and January is equal to \(2^\circ\mathrm{C}\). The situation remains almost unchanged until mid-April, the indicated temperature difference by this time amounting to \(2.2^\circ\mathrm{C}\). After this there follows a rapid, steady increase in the temperature difference. By mid-May it becomes equal to \(6.9^\circ\mathrm{C}\). It reaches its greatest value in June—\(8.0^\circ\); then, during the following two months, it gradually declines. In September it falls to \(3.4^\circ\) and then, having reached this level, steadily decreases over the next three months to the lower limit of \(2.0^\circ\) at the end of the year.

From what has been said it is evident that, approaching the question from the side just examined, one may conclude that the period of greatest dampening in Siberia falls in the time from mid-April to mid-August. The greatest dampening appears in the month of June, after which it subsequently declines rather rapidly toward August. Of greatest significance in the question of preserving sugar is the period of time from March to July. This circumstance must be taken into account in arranging sugar warehouses in Siberia.

Speaking of the possibilities of the dampening of sugar in Siberia from the quantitative side, one must take into consideration not only the dew point determined by the state of the atmospheric air with respect to its temperature and humidity, but, independently of this, it is also necessary to take into account the degree of cooling of the sugar when it enters the Siberian warehouses. In this connection it should be noted that, when shipped from the beet-sugar southern districts, the mass of sugar in the vast majority of cases travels along the Siberian railway for several weeks in December–January, i.e., at the time of the severest Siberian frosts, when the temperature sometimes falls to \(-35\)–\(-40^\circ\mathrm{C}\), and in general remains at a very low level. Thus this circumstance is connected with a regular, mass, intense cooling of the sugar before it reaches the Siberian warehouses. Obviously, this has its significance, since subsequently it causes a slowing of the warming of the sugar in the warehouses and contributes to an increase in the degree of its dampening.

Summing up the analysis made of the climatic conditions of Siberia with respect to the possibility and conditions of prolonged storage of sugar here in warehouses, one may draw certain general conclusions.

1. The climatic conditions of Siberia promote the possibilities of dampening of sugar during its prolonged storage in warehouses.

2. The constancy and inevitability in Siberia of temperature fluctuations and of humidity, with their considerable magnitude, indicate that the ultimate dampening of sugar in Siberia must be substantially greater than in the European part of the USSR in the regions of sugar production under the same storage conditions.

3. The possibilities of dampening are especially favored by February, the beginning of April, and chiefly the period from May to August. The greatest degree of development of the process of dampening is in June.

4. The transportation of sugar to Siberia in the coldest winter season contributes to an increase in the degree of dampening in the spring period, which is especially dangerous for sugar in its consequences.

The general conclusion comes down, first, to the inexpediency of making Siberia a place for the prolonged storage of considerable masses of sugar consumed here but produced in the modern beet-sugar regions of the European part of the USSR and, second, to the fact that the question of the one-time winter dispatch of sugar to Siberia is subject to thorough discussion with respect to the correctness of such a procedure for supplying Siberia with sugar, since it leads to depriving the Siberian consumer of the high-quality sugar produced by our factories, instead of which, under the indicated condition, a product that is exhausted to a greater or lesser degree enters Siberian circulation.

From what has been said in the preceding chapters it follows that the primary causes of the caking of sugar lie in changes in the temperature and humidity of the air in contact with the stored sugar.

Consequently, by excluding for sugar the possibility of contact with atmospheric air, one can thereby resolve the question of the successful storage of sugar without the danger of its caking and spoilage. This proposition leads to the noteworthy idea of storing sugar in silos from which the air has been pumped out, provided that the walls of such silos are air-impermeable.

The second form of a possible solution to the question of sugar storage may proceed from the predominant influence of temperature and from the significance of its fluctuations with respect to the deposition of dew. In connection with this arises the idea of sugar-storage facilities whose walls are impermeable not only to air but also to heat.

This condition may be satisfied, for example, by constructing storage facilities with double walls, between which there is an airless space. Obviously, a room of this kind gives impeccable storage results regardless of the practically possible temperatures of the sugar placed in it, but under the indispensable condition of its proper dryness. An excessively moist sugar will not be saved by such a storage facility from the unfavorable destructive influences lying within the sugar itself and, above all, in its excess moisture.

It is clear that the indicated methods of storage require special devices that have not yet been developed. The practice of sugar production, meanwhile, for the time being solves the question of sugar storage by using unheated warehouses for this purpose. The essence of this arrangement comes down to placing the sugar in an air space separated off from the atmospheric air. Moreover, this separation is by no means absolutely complete either with respect to the possibility of air exchange or to the penetration of heat from outside into the sugar room and back. This occurs through windows, doors, leaks in the floor and ceilings, owing to the air-permeability of the walls, etc. Thus, temperature fluctuations and, together with them, changes in the humidity of the air inside ordinary unheated warehouses are inevitable. These changes in their course are subject to the fluctuations of the temperature and humidity of the outside air, but at the same time they are also determined by the state of the internal air space, and also by the character of the structure, the material and thickness of the walls that separate this space from the atmospheric air. In addition, it must be borne in mind that the state of the air in the space under consideration is also under the influence of the mass of sugar stored here. Given a difference between the temperature of the sugar and the temperature of the air surrounding it, and in the absence of any artificial ventilation in the warehouse, favorable conditions are created for an uneven distribution of temperature, and consequently of humidity, in its air space.

All these circumstances must have substantial significance for the possibility and degree of caking of the stored sugar; moreover, they must also determine the rational arrangement of warehouses, as well as the conditions for the proper servicing of the latter. Thus, the question under consideration is connected with elucidating the changes in the temperature and humidity of the air in the sugar-storage room under the influence upon it of the temperature both of the sugar stored there and of the outside air. Consequently, the main question of rational—

storage of sugar in warehouses is reduced to establishing the temperature regime of the sugar warehouse and to ascertaining its changes over time.

Obviously, this regime will vary depending on where the warehouse is located, on the arrangement of such a warehouse, etc.

Being interested in the conditions of sugar storage in Siberia, we shall dwell on the case corresponding to the Sakhartrest warehouse in the city of Tomsk and, with reference to this case, attempt to determine the temperature regime of a sugar warehouse in Siberia for 1926, during the spring and summer period of the first half of the year, from March through July inclusive, which is here the most dangerous period for sugar dampening. In determining the temperature regime of a warehouse it is necessary to be able simultaneously to establish the temperature for the most varied and, at the same time, numerous points of the air space of such a warehouse. These points are places near the walls, in the corners of the building, on the floor, at various distances from the walls and from the sugar; the same is true at various levels above the floor, at the ceiling level, under the roof, etc. In order to carry out this task, with limited time for the work and with a shortage of thermometers, the author had to develop and establish observations of the warehouse temperature by the bubble method.

It consisted in the following: throughout the warehouse, at the points of interest in its space, thin-walled glass jars, capacity 75 cubic cm, with tight-fitting lids, were placed and suspended at various heights. Into each jar 20–35 cubic cm of ligroin or pure alcohol was poured, i.e., a non-freezing liquid, since the work was initially conducted in winter. In the jars placed away from the sugar, ligroin was poured. The temperature of the warehouse was determined by measuring it in the liquid of the aforementioned jars by immersing in them a thermometer giving 0.1°C. Thus, with 2–3 thermometers it was possible, in a short interval of time, almost simultaneously to determine the temperature of the warehouse at any point of interest.

In addition, the relative humidity of the air was determined in the middle of the warehouse at a distance of 0.5 meter from the floor of the lower story and above the upper layer in the warehouse at a distance of 2.0 meters below the roof of the warehouse. The humidity was determined by a psychrometer.

Measurements were made from 2 to 3 o’clock in the afternoon, in individual cases from 8 to 9 o’clock in the morning. At the same time, the temperature and humidity of the outside air were measured. In addition, the state of the weather was noted. All observations at the warehouses were made according to the author’s instructions and under his supervision by the chemist V. V. Tikhomirov.

The Sakhartrest warehouse under investigation, located in the city of Tomsk on Dukhovskaya Street, No. 2, is a brick, substantially constructed building with an overall length of 45 meters, a width of 14.5 meters in one part and 11.0 meters in another part, under an iron single-pitch unheated roof facing south. There is no ceiling. The height of the southern wall is 4.7 meters, of the northern 7.3 meters. At a height of 3.8 meters above the level of the lower floor a second wooden floor has been built of thick boards laid on wooden beams. The lower floor, situated at ground level, is partly simply wooden, partly wooden on a concrete bed, beneath which there is a thick layer of pebble stone.

The building is elongated in an east–west direction. The entire warehouse is divided into 7 compartments, also called “warehouses” by their corresponding numbers. One iron door leads into each such lower warehouse; above it, at the level of the second floor, there is a round framed shuttered window about one meter in diameter. In each compartment there is only one door and one window above it. All of them are located exclusively in the southern wall. In individual compartments, at the level of the lower floor, there are narrow, non-closing vents fitted with a wire grating. In each compartment of the warehouse, in the upper part of the roof, i.e., by the northern wall, there are several exhaust...

wooden pipes installed above the roof. Under each such pipe, in the flooring of the second floor, there are openings, apparently intended for drawing damp air out of the lower part of the warehouse.

Similar openings are made in the second floor near the transverse stone walls, in their middle. In addition, in the same floor there are wide and long cut-outs above the wooden stairways connecting the two floors. Since, in addition to all these cut-outs, the floor of the second story, which is a second deck of boards on beams, has many loose joints and cracks, there is therefore very weak isolation between the lower and upper compartments of the warehouse. On the lower wooden floor the sugar lies on decking of ordinary construction. On the lower floor of each compartment of the warehouse, 4–5 carloads of sugar packed in sacks are stacked; on the upper floor, 2–3 carloads. The sugar is stacked wagon by wagon in piles, with passages between them. On the lower floor the sacks lie in 6–9 rows, on the upper—in 4 rows.

The warehouse under consideration, according to the statement of representatives of Sakhartrest, is the most modern in Siberia and undoubtedly the best in Tomsk.

Observation was established for the extreme eastern compartment, called “warehouse No. 7,” and for the compartment called “warehouse No. 5.” During the present work the sugar was sometimes unloaded and sometimes loaded in these “warehouses,” which disturbed both the system of observation points set out and the temperature distribution that had become established in the warehouses. Nevertheless, in its main features the situation still appeared sufficiently clear.

In order to avoid encumbering the exposition with a large amount of numerical material, only summary comparisons are given below, concerning the distribution of temperatures in the warehouse in horizontal planes of the lower and upper floors in connection with the influence of the southern and northern walls. In addition, the distribution of temperature in the vertical direction is given for the transition from the floor level of the lower story to the higher levels of the warehouse under the roof.

To clarify the temperature conditions of the warehouse, Tables 13, 14, 15 and 16 are presented, giving, by day from March 15 to July 1, 1926, the change of temperature in the planes of the lower and upper floors of the warehouse, with the levels separated from one another by 3.8 meters. The temperature readings are linked to definite points, differing from one another in their distance from the southern and northern outside walls of the warehouse. These distances range from 0.1 to 7 meters, i.e., to the middle of the warehouse. For each reporting day, in the corresponding tables, the simultaneously measured outdoor-air temperatures are given for warehouse No. 7; in the tables for warehouse No. 5 these have been replaced by the mean daily outdoor-air temperatures. These data, mutually supplementing one another, are equally applicable, in the case under consideration, to both warehouses.

The data of Tables 13–16 indicate that the temperature conditions of the warehouse space are very diverse and, over time, change both absolutely and relatively. The warmest spaces are those along the southern wall and in the upper horizons of the warehouse; the coldest are the spaces along the northern wall and at the lower levels of the warehouse. In the worst conditions with respect to the possibility of warming are the bottom of the middle of the warehouse and the space situated along the lower edge of the northern wall. During the period of time beginning in March, the temperature of the space at the lower levels of the warehouse always remains below the mean daily outdoor-air temperature; thus, in March, for warehouse No. 5 the corresponding difference is 2.1°. In the following months, with the onset of warmth, it increases in May to 2.9° and in June to 7.2°. The same is observed with respect to warehouse No. 7. For convenience of comparison, Tables 17 and 18 are presented, giving the mean monthly temperatures established for individual points of the lower and upper floors, depending on the distance of these points from the outside southern and northern walls of the warehouse.

TABLE 13.

Temperature measurements of warehouse No. 5 in the plane of the upper floor as one moves away from the southern and northern exterior walls toward the middle of the warehouse.

Months	Date	Mean daily outside air temperature, °C	Lower floor of warehouse No. 5. Temperature in °C at a distance from the exterior southern wall of the warehouse, m: 0.1 m	Lower floor of warehouse No. 5. Temperature in °C at a distance from the exterior southern wall of the warehouse, m: 0.5 m	Lower floor of warehouse No. 5. Temperature in °C at a distance from the exterior southern wall of the warehouse, m: 5 m	Lower floor of warehouse No. 5. Temperature in °C at a distance from the exterior northern wall of the warehouse, m: 6 m, mean	Lower floor of warehouse No. 5. Temperature in °C at a distance from the exterior northern wall of the warehouse, m: 1 m	Lower floor of warehouse No. 5. Temperature in °C at a distance from the exterior northern wall of the warehouse, m: 0.1 m
March	15	2.3	−4.0	−3.7	—	−4.0	−4.0	−4.2
March	19	0.2	1.5	0.0	2.5	2.1	—	1.5
March	20	1.1	2.0	1.5	2.0	1.4	1.4	2.0
March	22	1.1	3.0	1.2	2.4	2.4	1.2	1.8
March	23	−5.0	0.5	−1.4	−0.5	−0.5	−1.0	−0.4
March	26	−1.3	2.5	1.5	3.0	3.0	2.4	2.8
March	30	−6.0	—	−0.8	−0.8	−0.2	—	−0.5
March	31	−4.9	0.0	—	1.0	1.0	0.0	0.6
April	1	−2.8	0.2	—	0.5	0.6	0.9	0.5
April	2	1.5	0.2	−0.4	0.2	0.2	−0.2	0.0
April	6	−0.9	1.0	1.0	1.0	1.0	0.8	0.8
April	10	1.4	1.5	1.5	1.6	1.6	1.6	1.8
April	16	7.5	4.8	4.8	4.5	4.5	4.5	4.5
April	20	0.1	3.5	3.5	3.5	3.5	3.5	3.5
April	21	1.3	3.6	3.2	3.6	3.6	3.4	3.4
April	22	0.9	4.5	4.4	4.8	4.8	4.0	4.0
April	23	2.0	5.8	5.4	5.5	5.5	5.5	—
April	27	7.9	7.3	7.3	—	7.5	7.6	—
April	28	4.2	6.4	6.4	—	6.0	6.0	6.2
April	29	−3.3	3.9	3.9	—	3.9	4.1	1.8
May	6	18.2	8.5	8.2	—	9.2	7.7	8.7
May	7	9.7	11.5	11.0	—	11.0	10.2	10.5
May	8	−3.5	4.5	4.8	—	5.0	5.0	5.2
May	10	−3.1	3.4	3.4	4.4	4.0	4.0	3.8
May	11	−2.3	2.4	2.4	—	3.4	3.0	3.0
May	12	−1.3	4.0	4.0	4.5	4.7	4.4	4.8
May	13	2.1	5.6	5.4	5.5	5.4	—	5.5
May	15	7.1	8.3	7.8	9.5	9.0	—	8.8
May	19	1.9	7.0	6.7	6.7	—	—	7.0
May	21	3.5	5.5	5.4	5.7	—	5.4	5.3
May	25	4.1	6.3	6.0	6.8	6.6	6.3	6.8
May	26	6.4	—	7.8	9.7	9.3	8.6	9.7
May	27	11.3	9.7	9.3	9.0	9.0	8.5	9.0
June	1	6.1	—	11.6	13.0	12.0	11.8	12.5
June	2	7.5	—	10.0	—	10.2	10.3	—
June	3	12.5	—	12.0	12.4	12.6	11.6	12.6
June	11	18.6	7.4	8.0	7.5	—	—	—
June	15	22.5	23.8	23.5	23.8	—	24.0	24.8
June	18	19.4	21.5	21.4	21.8	—	21.7	22.5
June	24	25.2	25.0	24.7	25.0	25.5	24.5	26.0
June	25	26.2	26.7	26.6	26.6	27.5	26.4	27.5
June	26	24.3	27.5	27.0	27.8	28.5	27.0	28.0
June	30	14.9	22.0	22.3	22.3	22.4	23.3	23.0

TABLE 14.

Changes in the temperature of warehouse No. 5 in the plane of the lower floor as one moves away from the southern and from the northern exterior wall toward the middle of the warehouse.

LOWER FLOOR OF WAREHOUSE No. 6.
Temperature in °C at a distance.

Months	Day	Mean daily temperature of outside air, °C	From the exterior southern wall of the warehouse, m: 0.1 m, on the floor	From the exterior southern wall of the warehouse, m: 0.5 m, on the floor	From the exterior southern wall of the warehouse, m: 1.5 m, on straw	From the exterior northern wall of the warehouse, m: 6 m, on straw	From the exterior northern wall of the warehouse, m: 6 m, on the floor	From the exterior northern wall of the warehouse, m: 0.5 m, on the floor	From the exterior northern wall of the warehouse, m: 0.1 m, on the floor
March	15	2.3	−4.5	−4.5	−5.0	−5.0	−4.5	—	−5.5
March	19	0.2	−2.5	−2.2	−2.0	−3.0	−3.5	−3.0	−3.0
March	22	1.1	−2.0	−2.0	—	−2.2	−2.5	−3.0	−3.0
March	23	−5.0	−2.0	−2.0	—	−2.2	−3.0	−3.2	−3.2
March	26	−1.3	−1.0	−1.0	—	−1.8	−2.0	−2.0	−2.0
March	27	−0.7	−1.5	−1.0	−1.4	−1.0	−2.0	−2.5	−2.0
March	30	−6.0	−2.0	−2.0	−2.0	−2.0	—	—	−2.5
March	31	−4.9	−2.0	−2.0	—	−2.8	−2.5	−2.8	−2.5
April	1	−2.8	−1.2	—	−1.0	−2.2	−2.0	−2.2	−2.2
April	2	1.5	−1.4	—	−1.4	−2.4	−2.4	−3.0	−2.5
April	3	2.1	−0.5	−1.2	−1.2	−1.5	−2.0	−1.5	−1.0
April	6	−0.9	−1.0	—	−1.0	−1.0	−1.5	—	−2.0
April	8	−1.3	−0.5	−1.0	−1.0	−1.0	−1.0	−1.6	−1.4
April	10	1.4	−0.8	−0.8	0.0	−1.0	−0.5	−1.8	−1.6
April	13	−1.0	−0.8	−0.8	−0.8	−0.5	−1.2	−1.6	−1.6
April	16	7.5	−0.5	−0.5	—	−0.7	−0.7	−0.7	−0.4
April	20	0.1	0.5	0.5	0.5	0.2	−0.5	−0.5	−0.5
April	21	1.3	0.5	0.4	0.5	0.0	0.0	0.0	0.0
April	22	0.9	1.2	0.8	1.0	—	0.4	0.0	0.0
April	23	2.0	0.5	0.5	—	0.5	0.4	0.0	0.0
April	29	−3.3	0.7	0.5	0.5	0.7	0.0	−0.3	−0.2
May	6	18.2	2.0	1.2	—	2.0	1.5	—	1.7
May	8	−3.5	1.7	1.5	1.5	1.5	1.8	0.7	0.6
May	10	−3.1	1.0	0.7	—	1.2	1.0	1.0	—
May	11	−2.3	−0.8	−0.8	0.2	−0.2	0.5	—	—
May	12	−1.3	0.2	0.0	0.8	0.6	1.2	—	—
May	13	2.1	1.4	—	1.7	0.7	0.7	0.7	0.4
May	14	5.7	1.8	1.8	1.8	1.7	1.8	0.8	0.7
May	15	7.1	2.5	2.5	2.8	2.4	1.5	1.5	1.2
May	19	1.9	2.5	2.5	3.2	2.5	1.7	1.7	1.5
May	25	4.1	2.0	2.0	2.0	2.4	1.7	—	1.3
May	27	11.3	3.3	3.5	6.4	3.7	2.7	2.7	2.0
June	1	6.1	4.9	5.2	5.4	5.2	3.6	3.4	3.2
June	2	7.5	5.3	5.3	5.9	5.0	3.9	3.5	3.4
June	4	14.1	6.3	6.5	7.4	6.8	5.5	—	5.0
June	11	18.6	8.2	8.0	9.7	7.7	6.4	5.8	5.8
June	15	22.5	10.3	11.8	—	13.5	10.2	10.0	10.0
June	18	19.4	11.8	12.3	—	11.8	11.0	11.0	10.0
June	24	25.3	13.0	13.5	—	13.5	11.0	—	11.5
June	25	26.2	14.7	16.0	—	16.0	12.7	13.0	13.5
June	26	24.3	14.7	16.0	—	16.5	13.5	14.0	14.2
June	30	14.9	15.0	15.3	—	15.0	13.5	13.8	13.8

TABLE 15.

Change in the temperature of warehouse No. 7 in the plane of the upper floor as one moves from the southern and northern walls toward the middle of the warehouse.

UPPER FLOOR OF WAREHOUSE No. 7 — Temperature in °C at a distance

Month	Date	Outdoor air temperature at 2–3 p.m.	From the outer southern wall: 0.1 m	4 m	6 m	7 m, middle	From the outer northern wall: 6 m	5 m	0.5 m	0.1 m
March	15	9.6	−3.5	−3.5	−4.0	−4.5	−3.5	−3.5	−4.0	−4.5
March	16	5.0	−0.5	+0.5	−0.5	0.0	0.0	±0.0	−1.0	0.0
March	20	5.0	1.7	−3.0	0.5	—	1.7	−0.5	−0.5	−0.6
March	22	5.0	2.0	1.0	0.5	0.0	1.5	0.0	−0.5	0.8
March	23	−2.0	0.0	−0.6	−0.5	−0.5	−0.5	−0.5	−1.0	−0.5
March	26	5.0	1.6	1.0	0.8	1.0	1.0	1.0	−1.2	1.0
March	27	−0.5	1.0	0.0	−0.7	−0.5	0.0	0.3	−0.5	0.0
March	30	−0.4	−0.5	−1.5	−1.5	−1.2	−1.4	−1.4	−1.5	−1.0
March	31	3.0	−0.5	−1.0	−1.0	−1.0	−1.0	−1.5	−1.5	−0.5
April	1	3.5	0.2	−1.0	−1.0	−1.4	0.0	−1.0	−1.5	−1.0
April	2	2.8	0.0	−0.4	−0.6	−0.6	−0.6	−0.6	−1.2	−0.4
April	3	4.5	0.6	−0.4	−0.2	−0.5	0.4	0.4	−1.0	−0.4
April	6	0.5	0.5	—	0.5	0.5	0.5	0.0	0.2	0.5
April	8	4.0	0.2	0.2	0.2	0.2	0.8	0.0	0.0	0.2
April	10	3.5	0.8	1.0	1.0	0.5	0.5	—	0.0	0.8
April	13	2.5	1.0	0.8	0.8	—	—	0.8	0.5	0.5
April	16	11.5	4.4	—	3.8	—	—	3.0	—	3.5
April	20	0.5	3.5	3.6	3.0	—	—	3.2	—	5.0
April	24	10.0	5.8	4.5	4.5	4.0	4.5	4.0	3.6	4.0
April	27	11.0	7.5	6.0	6.0	5.5	6.0	—	5.0	6.0
April	28	6.2	6.2	5.3	5.2	4.8	—	4.7	4.6	5.0
April	29	−0.5	3.5	—	3.4	3.3	2.9	3.2	2.9	3.0
May	6	18.8	7.5	—	6.5	6.0	6.0	6.6	5.0	6.2
May	7	19.0	8.5	—	7.6	—	8.5	8.0	7.2	7.5
May	8	0.3	3.7	3.6	3.5	3.5	3.2	4.0	3.5	3.7
May	11	0.7	2.0	1.8	2.2	2.4	2.2	1.7	1.7	1.7
May	12	5.0	3.4	3.4	3.4	3.0	3.8	—	2.5	2.8
May	13	7.0	4.0	3.5	3.7	3.4	3.8	4.0	3.7	3.5
May	14	12.5	5.6	5.3	5.3	4.8	5.0	5.5	3.8	5.0
May	15	14.0	7.0	6.3	6.2	5.7	6.4	7.2	5.0	6.2
May	20	5.4	4.7	4.6	4.8	5.3	4.7	3.8	4.8	4.5
May	25	4.6	5.4	5.3	5.5	5.0	5.4	—	—	4.8
May	26	11.4	7.5	7.0	6.8	6.5	6.7	5.5	5.5	6.7
May	29	15.5	11.2	10.6	10.4	9.4	10.4	9.9	9.9	10.0
June	4	18.8	14.0	—	13.6	—	13.4	—	9.8	10.0
June	12	24.0	—	19.5	17.5	15.8	17.2	—	15.5	—
June	15	25.0	23.4	—	21.8	21.0	—	—	—	—
June	17	22.5	20.7	—	19.7	19.0	19.7	—	19.6	19.6
June	22	28.4	22.8	21.6	22.8	20.8	21.5	—	21.4	21.6
June	24	32.0	24.4	24.0	23.6	22.5	23.0	—	22.0	23.4
June	25	25.0	26.0	24.5	25.0	23.6	24.6	—	23.0	24.8
June	26	31.0	27.0	25.5	24.4	—	25.5	—	24.8	25.0
June	30	20.0	21.8	21.0	21.0	21.4	20.7	—	21.0	20.7

TABLE 16.

Change in temperature of Warehouse No. 7 in the plane of the lower floor with distance from the southern and northern exterior walls along the middle of the warehouse.

Month	Date	Outdoor air temperature at 2–3 p.m.	From exterior southern wall, 0.1 m	From exterior southern wall, 7 m	From exterior northern wall, 4 m	From exterior northern wall, 3 m	From exterior northern wall, 1 m	From exterior northern wall, 0.1 m
March	15	9.6°	−4.5°	−4.5°	−5.0°	−5.5°	−5.0°	−5.0°
March	16	5.0	−2.0	—	−3.2	−4.2	−3.5	−3.5
March	20	5.0	−2.0	—	−2.9	−2.6	−3.4	−3.4
March	22	5.0	−1.7	—	−2.2	—	—	−2.5
March	26	5.0	−1.0	—	−1.4	−0.8	−1.6	—
March	27	−0.5	−1.2	—	−2.0	−1.4	−2.0	—
March	30	−0.5	−1.4	−2.5	−2.0	−2.4	−2.4	—
March	31	3.0	−1.0	−2.5	−1.5	−2.5	−2.5	−2.2
April	1	3.5	−1.5	−2.6	−2.2	−3.4	−3.0	−2.5
April	2	2.8	−2.0	—	−2.0	−2.4	−1.8	−1.8
April	3	4.5	−1.0	−2.0	−1.5	−1.8	−1.8	−2.0
April	6	0.5	0.0	−1.5	−1.5	−1.0	−1.5	−1.8
April	8	4.0	−0.8	−1.5	−1.0	−1.5	−1.2	—
April	10	3.5	−0.5	−1.0	−0.4	−0.5	−1.0	−1.0
April	13	2.5	0.2	−0.5	−0.8	−0.2	−0.8	−0.8
April	16	11.5	1.0	0.0	0.0	1.0	0.0	0.0
April	20	0.5	1.5	0.5	1.0	0.6	0.0	0.0
April	24	10.0	2.0	0.5	1.0	0.7	0.5	0.5
April	27	11.0	2.6	—	2.0	2.8	2.0	2.0
April	28	6.2	4.0	—	2.1	−1.3	−1.6	−1.6
April	29	−0.5	1.1	—	0.4	−0.7	−0.7	−0.7
May	6	18.8	3.6	—	2.7	2.5	2.0	2.2
May	7	19.0	6.5	—	4.7	4.7	4.7	4.7
May	8	0.3	1.5	—	0.4	−0.3	−0.3	−0.4
May	11	−0.7	0.2	—	−0.2	−0.3	−0.4	−0.4
May	12	5.0	1.3	0.5	0.5	0.2	0.2	0.2
May	13	7.0	1.8	0.8	0.8	0.5	0.5	0.5
May	14	12.5	2.4	0.7	1.5	1.4	0.8	0.8
May	15	14.0	4.0	2.0	2.0	1.7	1.5	1.5
May	20	5.4	2.4	1.7	1.7	2.4	1.8	1.7
May	25	4.6	2.8	2.0	2.0	2.2	1.7	1.7
May	26	11.4	2.8	3.0	2.4	3.7	2.3	2.4
May	29	15.5	6.4	—	5.6	5.5	5.5	4.8
June	4	18.8°	8.0	7.2	6.4	6.8	6.3	6.0
June	12	24.0	11.2	—	9.5	9.8	9.0	9.0
June	15	25.0	15.0	—	12.7	13.2	11.8	11.8
June	17	22.5	14.0	—	12.7	12.4	11.5	11.7
June	22	28.4	14.3	—	13.7	13.0	13.0	13.0
June	24	32.0	17.2	—	15.5	14.5	14.0	14.4
June	25	25.0	17.3	—	16.0	16.0	15.5	15.7
June	26	31.0	19.6	—	17.7	17.0	16.5	17.0
June	30	20.0	17.3	—	16.5	15.5	15.5	15.5

Table 17.
Average temperatures established for the lower and upper belts of warehouse No. 5 as a function of the distance from the outer southern and northern walls of the warehouse.

Month	Average outside air temperature for the month, °C	Lower belt, from southern wall: 0.1 m, on floor	Lower belt, from southern wall: 0.5 m	Lower belt, from southern wall: 1.5 m, at height	Lower belt, from southern wall: 6 m, at height	Lower belt, from northern wall: 6 m, at height	Lower belt, from northern wall: 0.5 m	Lower belt, from northern wall: 0.1 m	Upper belt, from southern wall: 0.1 m	Upper belt, from southern wall: 0.5 m	Upper belt, from southern wall: 5 m	Upper belt, from northern wall: 6 m	Upper belt, from northern wall: 1 m	Upper belt, from northern wall: 0.1 m
March	−4.3°	−2.2°	−2.1°	—	−2.5°	−2.5°	−2.7°	−3.0°	0.7°	−0.2°	1.3°	0.7°	0.0°	0.4°
April	2.1	−0.3	−0.2	−0.3	−0.8	−0.9	−1.1	−1.0	3.5	3.7	2.8	3.6	3.4	2.6
May	4.5	1.6	1.5	2.3	1.8	1.4	[[unclear: dot]]	1.3	1.2	6.5	6.3	6.7	6.9	6.3
June	17.6	10.4	10.1	—	10.1	9.2	9.3	9.0	22.0	18.7	20.0	19.5	20.1	22.1

TABLE 18.
Mean temperatures, established month by month for individual points of the lower and upper floors of warehouse No. 7, depending on the distance from the exterior southern and from the northern wall of the warehouse.

Months	Mean monthly temperature, °C	Lower floor of warehouse No. 7 — from the southern wall, 0.1 m	Lower floor of warehouse No. 7 — from the southern wall, 7 m	Lower floor of warehouse No. 7 — from the northern wall, 4 m	Lower floor of warehouse No. 7 — from the northern wall, 3 m	Lower floor of warehouse No. 7 — from the northern wall, 1 m	Lower floor of warehouse No. 7 — from the northern wall, 0.1 m	Upper floor of warehouse No. 7 — from the southern wall, 0.1 m	Upper floor of warehouse No. 7 — from the southern wall, 4 m	Upper floor of warehouse No. 7 — from the southern wall, 6 m	Upper floor of warehouse No. 7 — from the southern wall, 7 m	Upper floor of warehouse No. 7 — from the northern wall, 6 m	Upper floor of warehouse No. 7 — from the northern wall, 5 m	Upper floor of warehouse No. 7 — from the northern wall, 0.5 m	Upper floor of warehouse No. 7 — from the northern wall, 0.1 m
March	−4.3°	−1.9°	−3.1°	−2.3°	−2.8°	−2.9°	−3.3°	0.1°	−0.4°	−0.7°	−0.7°	−0.2°	−0.6°	−1.3°	−0.6°
April	2.1	0.5	−0.9	−0.2	−0.6	−0.8	−0.8	2.3	1.6	2.0	1.6	1.6	1.6	1.2	2.1
May	4.5	2.9	1.5	2.0	2.0	1.7	1.6	7.5	5.0	5.5	5.0	5.5	5.6	4.8	5.2
June	17.6	14.9	—	13.4	14.2	12.3	12.3	22.5	22.7	22.5	20.7	20.7	—	19.7	20.1

From the data presented, the influence of the southern and northern walls of the warehouse on the temperature of its interior space is clearly revealed. The southern wall contributes to raising it, and the northern wall to lowering it. But for the same horizontal sections of the warehouse, the temperature difference associated with this is very small and fluctuates within about one degree, rarely rising to \(2^\circ\) or higher.

In the absence of a basement, the lower level of the warehouse is subject to the cooling action of the ground. It is felt more strongly in the middle of the floor, but judging by the data obtained, even here it fluctuates within narrow limits: \(0.5^\circ\)—\(1.0^\circ\), in isolated cases rising somewhat higher.

Moving successively from the southern to the northern wall, while remaining in one and the same horizontal section of the warehouse, one can observe a continuous change in temperatures. It depends on the time of year, the state of the weather, the direction and strength of the wind, etc., and it changes continuously. Moreover, the course of these changes for any point inside the warehouse proves to be quite different from that for the outside air. The chief reason for this lies in the unequal rate of propagation of heat in the outside air, through the walls of the warehouse, inside it, and in the sugar itself. Owing to this, the temperature changes of the outside air are perceived by the interior space of the warehouse with a certain delay, which, when changes in the atmosphere are frequent and often abrupt, leads to the phenomenon noted above. And this inevitably results in the fact that the temperature and its changes in different places of the warehouse space turn out to be very unequal. Moreover, as is seen from the data given in the tables, there may be cases when in two mutually close points of the warehouse space at one and the same time heating is taking place in one, while cooling is taking place in the other.

The tables relating to the temperature changes of the lower floor of warehouse No. 5 give a comparison of the temperatures of this floor in the middle with the temperature on the matting laid on it under the sugar. From this comparison it is evident that the significance of the matting is less in winter and greater in summer; quantitatively, however, it is very small, amounting in most cases to about \(0.5^\circ\), and only in hot summer weather exceeding one degree, and in isolated cases reaching \(2\)—\(3^\circ\text{C}\) and even more.

The data of Tables 13—18 indicate that warehouses, even unheated ones, have very great significance in reducing the amplitude of temperature fluctuations of their air space in comparison with the amplitude of simultaneous changes in the temperatures of the outside air. This is clearly seen from the table given below.

TABLE 19.

By months	By mean daily temperatures of the outside air	Warehouse No. 5, bottom	Warehouse No. 5, top	Warehouse No. 7, bottom	Warehouse No. 7, top
March....	\(8.3^\circ\)	\(4.0^\circ\)	\(1.3^\circ\)	\(4.5^\circ\)	\(6.5^\circ\)
April,...	10.8	3.7	4.3	7.4	9.0
May.....	21.7	7.2	11.8	6.9	9.5
June,....	21.1	13.3	17.8	13.6	18.2

Thus, unheated warehouses Nos. 5–7 reduce the temperature fluctuations for the lower floor: in March from 8.3 to 4.0–4.5° and in June from 21.1 to 13.3–13.6°, while for the upper floor this same reduction in March ranges from 1.3 to 6.5° and in June from 17.8 to 18.2°.

All the foregoing indicates the extraordinary variegation and instability of the distribution of temperatures in the interior space of a warehouse. However, within one and the same level and at a definite moment in time these fluctuations nevertheless prove to be very small.

An entirely different situation is observed when comparing the temperatures of a warehouse along any of its vertical sections. A merely cursory examination and several comparisons of the corresponding data available in Tables 13–18 concerning the temperatures of the lower and upper floors of warehouses Nos. 5 and 7 are enough to make evident the extremely great influence of elevation of level on the temperature in the warehouse. The successive changes in the temperatures of the interior space of the warehouse along the vertical and their fluctuations over time determine what may be called the “temperature regime of the warehouse.” It is evident that the temperature regime and the humidity of an unheated warehouse are most closely connected with the temperature condition of the external atmospheric air and with its humidity. Under such conditions the humidity of the interior space of the warehouse must inevitably change, while always remaining different from that in the atmospheric air.

The indicated circumstance is clearly revealed by the data of Table 20, given below, on the temperature regime of the sugar warehouse in Siberia, in the city of Tomsk. This table was compiled from data taken during the period from March 15 to July 1, 1926, at intervals of 5–7 days. These intervals were chosen in order to make the table more graphic than what daily reports provide. By capturing characteristic turning points, it is possible under this condition to reveal more prominently the nature of the successive changes over time. As for the temperature of the outside air, it was taken in the form of readings in the yard in front of the warehouse, in the shade, at 2 o’clock in the afternoon, at the time when the warehouse temperatures were determined. Inside the warehouse the temperature was measured vertically in its middle, with temperature readings taken: at the level of the floor of the first story; on the decking on it beneath the sugar; at a height of two meters, beneath the decking of the floor of the second story; at a height of 1.5 meters above the floor of the second story and, finally, at a height of two meters above the floor of the second story and at a distance of 0.5 meter from the roof of the warehouse. In addition, the relative humidity of the outside atmospheric air and of the air space of the warehouse was established simultaneously on the floor of the lower floor and above the floor of the second story at the height of the upper level of the sugar lying here in four rows of sacks.

In order to present more clearly the essence of the data of this table, it is also presented in the form of diagrams in Drawing III. On these diagrams, at the corresponding points, the figures indicate the relative humidity at the top and bottom of the warehouse, as well as the relative humidity of the outside air, simultaneously measured outside the warehouse at 2 o’clock in the afternoon.

Table 20 and especially the diagrams of Drawing III clearly reveal the following.

The temperatures at the top and bottom of the warehouse always diverge sharply, and in the upper part of the warehouse it is considerably warmer than below. With a lowering of the external temperature this difference decreases, falling to 4.6°C (April 29), while with an increase in the temperature of the outside air it grows, reaching 22.8°C (June 24). The general nature of the change in the warehouse temperature regime is determined by the course of temperature fluctuations in the atmospheric air, but quantitatively this influence on the warehouse temperature is not reflected uniformly—namely, it is very strong at its upper levels and very weak at the lower ones.

The temperature of the warehouse during the period from March to July on the lower floor, over short intervals of cold periods, proves to be lower than the temperature of the outside air. The reverse situation is observed for the spaces of the warehouse lying above the level of the second floor.

TABLE 20

of the temperature regime of sugar warehouse No. 5 in the city of Tomsk for the period from March 15 to July 1, 1926.

Drawing III.

Month	Date	\(t^\circ\) of outside air at 2 p.m.	Lower (I) floor: at floor level	Lower (I) floor: at top of stack	Lower (I) floor: at height 2 m from floor	Lower (I) floor: relative humidity	Upper (II) floor: at floor level, II floor	Upper (II) floor: at height 1.5 m from floor, II floor	Upper (II) floor: at height 2 m from floor and 0.5 m from roof	Upper (II) floor: relative humidity	Humidity of outside air at 2 p.m.
March	19	+3.6	−3.4	−3.0	−1.5	—	+2.5	+5.0	+6.5	—	53
March	26	+1.4	−2.0	−1.7	0.0	—	+3.0	+4.2	+6.5	—	54
April	1	+2.6	−2.0	−2.2	−1.4	—	+0.6	+3.5	+4.5	—	54
April	8	−3.4	−1.0	−1.0	+0.2	—	+1.2	+4.0	+4.0	—	57
April	16	+11.4	−0.7	−0.7	+1.5	90	+4.5	+7.5	+9.0	61	56
April	23	+5.3	+0.4	+0.5	+2.4	94	+5.5	+10.0	+12.4	67	70
April	29	−2.4	0.0	0.7	+2.1	91	+5.9	+4.4	+4.6	71	84
May	6	+23.6	+1.5	+2.0	+4.5	100	+9.2	+13.2	+16.4	67	51
May	14	+9.2	+1.8	+1.7	+4.2	94	+7.3	+11.7	+14.5	51	42
May	21	+6.4	+1.4	+1.7	+3.8	94	+5.7	+7.7	+8.5	86	58
May	27	+15.6	+2.7	+3.7	+7.4	100	+9.0	+12.0	+13.5	51	44
June	3	+14.2	+4.0	+5.3	+8.2	88	+12.4	+17.0	+18.8	61	51
June	11	+23.3	+6.4	+7.7	+11.7	95	+7.5	+23.5	+25.0	51	51
June	18	+23.0	+10.0	+11.8	+18.2	86	+21.8	+27.5	+30.0	44	61
June	24	30.4	+11.0	+13.5	+18.5	100	+25.0	+31.5	+33.8	50	47
June	30	19.3	+13.5	+15.0	+18.5	100	+22.3	+25.0	+26.0	64	69

The relative humidity of the warehouse at the level above the second floor, i.e. above 2 meters, is very close to the humidity of the outside air and, for the period from the second half of March to July, fluctuates within the limits of 45–67%, only in isolated cases briefly rising somewhat higher.

A completely different situation is observed at the level of the lower floor. Here the humidity is usually kept very high, namely within the limits of 94–100%, only for short periods falling to 90–91%, and in exceptional cases even lower.

Let us now compare the foregoing with what was established regarding the temperature conditions and the limiting humidity of the air that precludes dampening of pure sucrose and of sucrose that has already begun to invert and decompose.

The limiting air humidity that precludes the possibility of dampening of good dry sugar consisting of pure sucrose, depending on temperature within the limits of 0–35 °C, corresponds, as was established, to 89.2–91% relative humidity of the air. The same, at the same temperature limits, for sugar already dampened and beginning to invert corresponds to 77.9–73% relative humidity of the air.

It follows from this that sugar lying on the second floor, two meters above the lower floor of the warehouse, is under conditions that exclude the possibility of its dampening. Given the easy possibility for air to penetrate from the upper story to the lower one—thanks to cracks and openings in the floor deck of the second story, as well as to the staircase—the case noted in the diagrams of the drawings—III, of a sharp short-term lowering of temperature in the upper half of the warehouse, is not dangerous. The reason for this is not only the conditions under which dew appears on the sugar of the upper floor, but also that the main mass of moisture precipitating out of the air, which in this case is cooled chiefly through the roof, settles on the sugar not of the upper but of the lower floor of the warehouse, to which, under the conditions noted, the air cooled at the top of the warehouse will inevitably flow down without hindrance. Thus, the temperature conditions and the humidity of the warehouse space above its second floor exclude the possibility of dampening of the sugar stored there, threatening it with drying out only if, of course, the sugar placed there is not sufficiently dry.

The completely opposite situation obtains for sugar stored in the warehouse under consideration on its lower floor. Everything established with complete definiteness indicates that the sugar placed there, regardless of its quality, the conditions of delivery, and storage there, is doomed to inevitable prolonged and deep dampening. The reasons for this are that, under the conditions of the Siberian climate, in the period March–June, in unheated warehouses of the indicated design, the air humidity and its temperature at the lower levels inevitably prove to correspond to the conditions of sugar dampening.

Thus it becomes clear that the variegation of the temperature conditions and, as a consequence, of the air humidity in the warehouse space leads to the fact that the conditions for storing sugar in different places of the warehouse will be very unequal. The upper spaces of the warehouse protect against dampening and favor drying out, whereas the lower ones promote dampening and spoilage of the sugar stored there. If one takes into account what has been established about the distribution of temperature in the horizontal sections of warehouses, it becomes obvious that within the warehouse, in some places there are concentrated warmer air spaces, in others colder ones, as it were bags of cold air stagnating there, where the sugar is under especially unfavorable conditions for being warmed in spring. With the low mobility of air in warehouses and with the impossibility, by the means usually employed in the form of exhaust pipes in the roof, of removing from the lower horizons of the warehouse the cold air stagnating there, it must be recognized that the principal cause of dampening of the stored sugar is the sharp difference of temperatures at the top and bottom of the warehouse. To eliminate this unevenness of heating means to correct the warehouse, to make it suitable for storing sugar without risk of dampening of the latter.

Without touching for the moment upon consideration of this question on its merits, let us dwell on elucidating the practically possible consequences of the dampening of sugar in Siberia when it is stored in the warehouses existing here, of the kind described. Since we are interested not only in the qualitative but also in the quantitative side of the effect of the dampening of sugar in Siberia, it is desirable to take a case in which dampening manifested itself over the longest period of storage. This is possible at the end of the warm season of the year, i.e., at the beginning of winter. In connection with this, below are given the results of an investigation of dampened sugar carried out by the author in 1925 at the Tomsk warehouse of Sakharotrest. By the time of the investigation of the dampening, i.e., by the beginning of October, the sugar had been in the above-described warehouse of Sakharotrest in the city of Tomsk. But the sugar under investigation had arrived at this warehouse only partly on September 18. Its storage up to that time, and the associated dampening of the sugar, had likewise taken place in the city of Tomsk, but in the warehouses of the “Transport Society.” These warehouses are essentially of exactly the same construction as the Sakharotrest warehouse analyzed above; that is, they are stone, one-and-a-half-story warehouses, under an unheated iron roof, with a wooden floor, iron doors, and small windows. The unglazed frames in the warehouses of the “Transport Society” made very little difference in the essential nature of the warehouse’s influence on the stored sugar as compared with what took place in the Tomsk warehouse of Sakharotrest. In view of this, the transfer of the sugar from the warehouses of the “Transport Society” to the Sakharotrest warehouse in no way changed the conditions of dampening of the sugar stored there.

The sugar under investigation (lump, granulated, and loaf sugar), in an amount of about 20 wagonloads, stacked on the lower floor of the warehouse, was arranged in piles by wagonload. From some of the piles, especially those that had become heavily dampened, the most damaged sacks were selected; these too were distributed here by wagonload.

Before samples were taken, each separate pile was weighed and inspected by representatives of Sakharotrest and of the Transport Society, who determined, by external appearance and by touch, the moisture of the lot under consideration. In doing so, the following designations were adopted for the different degrees of moisture observed: a “dry” lot, a “damp” lot, and an “obviously wet” lot.

Samples were taken separately from each lot, from different places in the pile and from different sacks, which differed, on the one hand, in their position in the piles and, on the other, in the unequal degree to which moisture had appeared. For each sample, depending on the condition of the lot, its uniformity, etc., from 5 to 8 sacks of the pile under consideration were taken. Some samples were taken from the outer layers directly beneath the fabric of the sack, by untying or cutting the latter in different places; other samples were taken from the very middle of the sugar mass, after first removing all its outer and upper layers. If a sack had become damp only in places or on one side, then some of the samples were taken from the outer dry layers, and some from the damp layers directly under the sack, etc. From each group of sacks, in addition, a general sample was taken, comprising, as far as possible, an average sample of the sacks selected from the pile for this purpose; in this sample the sugar was taken uniformly both from the outer and from the middle layers of each sack. The samples taken, each in an amount of 1–2.5 kilos, were immediately placed in clean, dry glass jars with ground-glass stoppers and rubber caps. The actual determination of the moisture of the individual samples was carried out by drying: initially for 2 hours at 65–70°C, then finally at 105°C.

In the table given below is presented a comparison of the moisture of individual samples from the various lots of the sugar under investigation. The table includes: lot number, type of sugar, place and time of its dispatch and receipt, number and character

sample and the moisture content of the sugar in weight percent. Each separate lot constituted a carload of sugar of 1,000 poods.

Dampening was revealed by the externally perceptible moisture of the bags in the lot; by damp spots on them, by complete soaking of the whole bag or of one side, and, finally, by the runoff of molasses that had flowed from the bags onto the warehouse floor beneath the matting. The last case corresponded to the degree of dampening of the sugar denoted, in the determination of the external appearance of the lots, as “obviously wet.”

When the sugar inside the bags was inspected, the latter was encountered with various manifestations of moisture, ranging from completely dry pieces to wet ones, partly turned into fines or else still retaining their shape, but easily falling apart into small pieces at the slightest pressure upon them.

The results of the investigation made of dampened sugars in the Tomsk warehouses are presented in Table 21 below.

It is evident from the table that the degree of dampening of the sugar varies within extraordinarily wide limits. From perfectly dry, even dried-out sugars with a moisture content of the general sample of 0.03–0.04%, there are lots with a moisture content of the general sample of up to 1.15% and with a moisture content of the sugar in the outer layers rising to 2.21%. In several lots the runoff of molasses from the bags was observed.

Alongside the processes of extreme dampening there is also manifested the result of the simultaneous process of drying out, which is easy to discern by comparing the moisture content of the outer, middle, and inner layers of the sugar.

In addition to lump and powdered sugar packed in bags, head sugar was also stored in the warehouse in the amount of 4 lots. Upon inspection all of them proved, according to the adopted terminology, to be “dry.” This sugar, packed in bags with straw, for each lot, when their weight was checked, gave a gain of from 73 to 148 kilograms per 1,000 poods.

The examination of the moisture content of the sugar, paper, and twine showed that in the very mass of the head sugar dampening was negligible, while the moisture precipitated from the air in this lot was absorbed almost entirely by the packaging, chiefly by the paper.

In general, the results of the analyses made of the sugar of individual lots stored in the Tomsk warehouses fully confirm the theoretical conclusions and inferences concerning the possibilities of dampening in unheated Siberian warehouses. Moreover, it turns out that the degree of dampening of the sugar may rise to threatening limits, completely depreciating the stored sugar.

Unheated warehouses, while undoubtedly protecting sugar from the unfavorable effects of the external atmospheric air, suffer greatly from the uneven distribution of temperature in general and especially from the divergence in the degree of heating of the air at the upper and lower horizons of the warehouse. The magnitude of this divergence had already been clarified in analyzing the temperature regime of the warehouse, using as an example the Tomsk warehouse of Sakhartrest No. 5. But in reality this divergence is even greater, since in the case analyzed for warehouse No. 5 the temperature readings both inside and outside the warehouse were compared only when taken simultaneously once per day, namely around two o’clock in the afternoon. Meanwhile, over 24 hours the temperature usually changes not only in the transition from day to night, but also independently of this; moreover, the temperature maximum and minimum may be very far removed from the midday reading. Naturally, these extreme limits of daily fluctuations considerably affect the temperature regime of the warehouse; however, the decisive significance in this respect belongs to the mean daily temperature of the outside air. In view of this, below, in Table 22, numerical material is given, established for tem—

TABLE 21

Moisture content of sugars.

Lot No.	Type of sugar	Place of dispatch	Time of dispatch and receipt in Tomsk	Condition of the lot by external appearance	Sample Nos.	Nature of the sample	Moisture content of the sugar in the samples, %
I	Lump	T. Timashevo	20/II–14/III	Moist	1/1	General	0.07
"	"	"	"	"	1/2	Outer layers	0.04
"	"	"	"	"	1/3	Middle layers	0.16
I-a	Lump	St. Timashevo	20/II–14/III	Clearly damp	I-a/1	General	0.54
"	"	"	"	"	I-a/5	Middle layers	0.21
"	"	"	"	"	I-a/7	Gen. outer layer	1.35
II	Lump	St. Odessa	28/I–10/III	Dry	2/7	General	0.26
"	"	"	"	"	2/8	Gen. outer layer	0.21
"	"	"	"	"	2/9	Middle layers	0.14
II-a	Lump	St. Odessa	28/I–10/III	Dry	II-a/10	General	0.50
"	"	"	"	"	II-a/11	Middle layers	0.30
III	Lump	St. Timashevo	19/II–14/III	Moist	3/12	General	0.22
"	"	"	"	"	3/13	Gen. outer layer	0.08
"	"	"	"	"	3/14	Middle layers	0.04
III-a	Lump	St. Timashevo	19/II–14/III	Moist	III-a/15	General	1.15
"	"	"	"	"	III-a/16	Outer dry layer	0.13
"	"	"	"	"	III-a/17	Outer moist layer	2.31
"	"	"	"	"	III-a/18	Middle layers	0.12
IV	Lump	St. Sumy	3/XII–7/II	Moist	4/19	General	0.35
"	"	"	"	"	4/20	Gen. outer layer	0.38
"	"	"	"	"	4/21	Middle layers	0.15
IV-a	Lump	St. Sumy	3/XII–7/II	Moist	IV-a/22	General	0.38
"	"	"	"	"	IV-a/23	Gen. outer wet layer	0.70
"	"	"	"	"	IV-a/24	Middle layers	0.19
V	Lump	St. Sumy	29/XII–5/I	Dry	5/25	General	0.18
"	"	"	"	"	5/26	Gen. moist sacks	0.28
"	"	"	"	"	5/27	Gen. outer layer	0.19
VI	Lump	St. Sumy	11–14/II-25	Dry	6/28	General	0.17
"	"	"	"	"	6/29	Gen. outer layer	0.12
"	"	"	"	"	6/30	Middle layers	0.04
VII	Lump	St. Timashevo	3/III–24/III-25	Dry	7/31	General	0.23
"	"	"	"	"	7/32	Gen. moist sacks	0.29
"	"	"	"	"	7/33	Gen. dry sacks	0.07
VIII	Lump	St. Timashevo	13/II–7/III-25	Dry	8/34	General	0.03
"	"	"	"	"	8/35	Outer dry layer	0.03
"	"	"	"	"	8/36	Middle layers	0.04
IX	Lump	St. Timashevo	13/II–7/III-25	Dry	9/37	General	0.08
"	"	"	"	"	9/38	Gen. outer layer	0.03
"	"	"	"	"	9/39	Middle layers	0.04
X	Granulated	St. Sumy	2/I–3/II-25	Clearly damp	10/40	General	0.42
"	"	"	"	"	10/41	Middle layers	0.18
"	"	"	"	"	10/42	Gen. outer moist layer	0.89
XI	Head sugar	St. Odessa	30/I–8/III	Dry	13/43	Gen. outer layer	0.21
"	"	"	"	"	"	Middle layers	0.10

TABLE 22

of the temperature regime of sugar warehouse No. 7 in the city of Tomsk for the period
from March 15 to July 1, 1926.

Month	Date	Outside air: temperature at 7 a.m., mean °C	Outside air: minimum °C	Outside air: maximum °C	Outside air: relative humidity at 7 a.m., %	In warehouse No. 7, below at the floor level of the 1st story: temperature at 2 p.m., °C	In warehouse No. 7, below at the floor level of the 1st story: minimum °C	In warehouse No. 7, below at the floor level of the 1st story: relative humidity, %	In warehouse No. 7, above at 1.5 m above the floor of the 2nd story: temperature at 2 p.m., °C	In warehouse No. 7, above at 1.5 m above the floor of the 2nd story: maximum °C	In warehouse No. 7, above at 1.5 m above the floor of the 2nd story: relative humidity, %
March	15	2.3	−4.3	9.6	65	−5.5	−8.0	—	−3.0	−3.0	—
March	20	−1.1	−4.6	3.4	60	−2.6	−6.0	—	7.6	10.0	—
March	23	−5.0	−8.0	−3.0	97	−3.2	−4.5	—	−0.5	10.0	—
March	26	−1.3	−3.0	1.3	66	−0.8	−3.5	—	4.4	6.0	—
March	30	−6.0	−10.3	−2.1	86	−2.4	−3.5	—	0.5	1.5	—
March	31	−4.0	−10.4	−1.2	81	−2.5	−3.8	—	2.2	5.2	—
April	1	−2.8	−12.4	2.6	70	−3.4	−5.0	—	2.8	5.8	—
April	2	1.5	−4.8	5.4	78	−2.4	−3.0	—	2.4	4.5	—
April	6	−0.9	−3.2	1.3	76	−1.0	−3.0	—	1.5	1.6	—
April	8	−1.3	−8.1	2.5	71	−1.5	−1.5	—	3.0	4.5	—
April	16	7.5	1.6	11.4	70	1.0	−1.0	88	7.5	10.0	78
April	20	0.1	−0.8	1.1	85	0.6	−0.8	94	4.0	16.5	72
April	24	4.4	−3.0	8.3	62	0.7	−1.5	92	8.5	14.5	80
April	27	7.9	4.4	11.4	82	2.8	0.5	96	10.0	18.5	84
April	29	−3.3	−5.4	−2.4	83	−0.7	0.0	84	5.2	5.0	67
May	6	18.2	7.2	23.6	62	2.5	−2.0	95	12.4	21.0	65
May	7	9.4	−0.8	15.2	64	4.7	4.5	79	11.5	22.5	65
May	11	−2.3	−5.3	0.6	65	−0.5	−1.5	98	4.3	6.2	79
May	14	5.7	−5.5	9.2	54	1.4	0.0	100	11.0	18.0	66
May	25	4.1	0.0	4.8	71	2.2	—	—	8.0	—	—
May	26	6.1	0.1	9.5	53	3.7	1.4	95	12.5	18.4	57
May	29	12.7	1.0	13.8	76	5.5	2.5	86	14.3	21.0	78
June	2	7.5	0.7	10.0	47	5.3	3.7	77	13.7	21.0	67
June	3	12.5	6.6	14.2	50	5.0	4.3	80	14.0	19.0	65
June	4	14.1	6.8	18.5	55	6.8	4.5	93	17.0	25.0	51
June	11	18.6	10.4	23.3	66	10.2	5.0	100	20.0	26.0	52
June	15	22.5	13.2	28.6	73	13.2	7.5	100	28.0	35.0	50
June	17	16.9	4.7	20.2	68	12.4	9.5	79	25.0	31.5	69
June	18	19.4	7.2	23.0	68	12.4	9.5	84	25.0	32.0	61
June	22	22.4	9.7	27.0	61	13.0	10.0	89	26.0	34.0	64
June	24	25.2	12.7	30.4	63	14.5	11.5	85	30.0	36.0	43
June	25	26.2	15.3	32.0	72	16.0	13.0	94	30.5	39.0	63
June	26	24.3	17.9	29.4	73	17.5	14.0	100	31.6	38.0	54
June	30	14.9	10.0	19.3	78	15.5	14.0	85	25.0	37.5	68

temperature regime of the Tomsk warehouse of Sakharotrest No. 7, where simultaneous temperature readings inside the warehouse at two o’clock in the afternoon are compared with the mean daily, as well as the minimum and maximum, temperature of the outside atmospheric air. In doing so, attention is also paid to the temperature minimum at the bottom and the maximum at the top of the warehouse, established in the interval between two immediately consecutive readings inside the warehouse. In addition to all this, the indicated table also includes the mean daily humidity of the outside air.

The data of this table, while fully confirming the basic propositions that followed from consideration of the case of warehouse No. 5, and extending still more widely the already established temperature divergence between the top and the bottom of the warehouse, at the same time point to yet another circumstance, namely, the influence of radiant solar heat on the warehouse. This action is very clearly revealed by the maximum thermometer placed, in this case, inside the warehouse under its uninsulated roof. The action of this radiant heat explains the exaggerated readings of the maximum thermometer inside the warehouse in comparison with the ordinary readings of the maximum thermometer of meteorological stations, where it is placed in the shade.

As is evident from the tables, beginning in mid-April, i.e. with the onset of the warm spring season and the beginning of the period of prolonged sunny days, the temperature maximum on the second floor of the warehouse rapidly increases, rising to heights that usually exceed the daily maximum of the outside air.

Since the radiant heat of the sun is received by warehouses chiefly through the roof and partly through the southern wall, this creates a new factor that intensifies the divergence in the degree of heating at the top and at the bottom of the warehouse. This is especially strongly manifested with uninsulated iron roofs, most sharply affecting, in such cases, warehouses that have no ceilings.

If one takes into account the peculiarities of the Siberian climate, characterized by a rapid transition from severe winter to warm summer, when the sugar in the warehouse in general, and especially on the floor of the first story, still retains a fairly low winter temperature, then the unconditional necessity of ceilings for Siberian warehouses intended for storing sugar becomes understandable. Summarizing the chief propositions clarified in the preceding exposition regarding the suitability of unheated warehouses for storing sugar in general, the following may be noted.

In unheated warehouses in Siberia, it is possible successfully to preserve without dampening only that portion of the sugar which lies at a certain height in the warehouse. The cause of the inevitable dampening of sugar at the lower levels of the warehouse is due to the stratification of the air in it into warm air, gathering above, and cold air, accumulating below. Usually, having no outlet, it becomes stagnant there and thereby retards the warming of the sugar in spring. As for the warming of the sugar itself, it proceeds following the rate of the developing warming of the warehouse air, with only a slight lag behind it. According to the data of Prof. Herzfeld¹, in unheated warehouses in Germany the warming of the sugar proceeds in the order shown in Table 23 below.

In general, the warming of the sugar develops parallel to the warming of the warehouse air with a very small lag behind it: in December by 2.4°, in April by 2.0°, and in May by 4.9° on average for the month.

In the survey carried out in Siberia, the conditions provided to the warehouses for work excluded the possibility of systematic observation of the temperature of the sugar stored in the warehouse; however, the fragmentary observations made in May and June also indicate that the lag

¹ “Z. K. O.” 1905, p. 339.

the warming of the sugar from the air surrounding it in the warehouse is very slight. In May and June this lag of the temperature of the sugar in the bags behind the temperature of the surrounding air fluctuated, depending on the location in the warehouse, from 1.1 to 4.3°C.

TABLE 23.

Time of observations	At noon °C: in the warehouse	At noon °C: outside	At noon °C: in the mass of sugar	In the warehouse °C: maximum	In the warehouse °C: minimum	In the warehouse humidity: maximum	In the warehouse humidity: minimum	Outside °C: maximum	Outside °C: minimum	Outside humidity: maximum	Outside humidity: minimum
1902
December 13–21 . . .	3.6°	3.4°	0.3°	10	−14.0	100%	82%	14.5	−15	95%	83%
1903
January 2–31 . . .	1.2°	2.4°	1.8°	7	−9.4	100 ›	75 ›	10	−8.8	86 ›	72 ›
February 2–28 . . .	2.3°	2.2°	4.8°	10	−4.5	100 ›	69 ›	11	−5.5	86 ›	66 ›
March 2–31 . . .	7.6°	7.1°	6.0°	14.6	1.8	100 ›	65 ›	18	1.2	80 ›	61 ›
April 1–30 . . .	7.8°	7.9°	5.9°	14.2	2.4	100 ›	56 ›	20.4	3.0	80 ›	64 ›
May 1–30 . . .	12.4°	15.9°	11.0°	22	6.0	87 ›	67 ›	33	4.5	75 ›	50 ›

An analysis of the temperature regime of unheated sugar warehouses leads to the conclusion that preventing the phenomenon of stratification of the air in the warehouse, or at least eliminating the situation thereby created, must lead to an improvement in the suitability of unheated warehouses and to the clarification of ways of rationalizing both the construction of warehouses and the methods of servicing them.

In order to eliminate one or another phenomenon, it is necessary to know its cause; but what is the cause of the stratification of the air in an unheated warehouse? Obviously, it lies in the daily alternation of the warm part of the day with the relatively cold night. When the temperature of the warehouse falls, the air cooled in it, being heavier, sinks downward; when it is heated, becoming warmer and lighter, it rises to the upper levels of the warehouse. The sharper the change between daytime and nighttime temperature, the stronger the stratification of the air in the warehouse. In this respect Siberia, as has already been explained, is under very unfavorable conditions. The situation here is made still worse by sharp and often unexpected changes in the weather, with transitions from cold to warmth and vice versa, which likewise leads to the same stratification of the air in the warehouse.

Obviously, since these causes lie in natural conditions, there is no possibility of eliminating them; consequently it remains only to eliminate or mitigate their consequences for the warehouse, i.e., the stratification of the air in it into warm air above and cold air below. In the clarification of these possibilities lie the means of rationalizing the construction of warehouses for storing sugar and of clarifying the proper methods of servicing them.

The negative side of the stratification of air in the warehouse consists in the presence of its lower cold layer. Consequently, eliminating the latter is a means of improving the operation of the warehouse. This can be accomplished by directly removing the cold air from the warehouse and replacing it with warmer air taken from outside. Another means may be the mixing, for example by electric fans, of the cold air at the bottom of the warehouse with its warm upper layers, without resorting to the introduction of outside air beyond natural ventilation. Such a method, at certain periods of the year, would be quite possible from the standpoint of the heat balance, especially if the radiant heat of the sun is utilized through the roof and the southern wall of the warehouse. Finally, a third method consists in heating the cold air of the warehouse by means of special heating devices placed directly in the warehouse to the required temperature and corresponding humidity, excluding the possibility of the sugar becoming damp. Moreover, at the top of the warehouse it will still invariably be warmer than at the bottom of the warehouse.

In unheated warehouses the question of removing cold air from them is usually solved by installing exhaust pipes in the ceiling (if there is one) and in the roof of the warehouse. The inexpediency of such a method is obvious in itself, since under such conditions the cold, heavy air in the lower part of the warehouse has no visible impelling reasons for rushing to exhaust pipes in the roof of the warehouse that are far from it. On the contrary, all the conditions exist for this cold air of the warehouse in spring and summer (see the diagrams of drawing III) to be removed from the warehouse by flowing into the space of the outside air, which surrounds it more easily, through channels beginning at the floor of the warehouse. Naturally, for this it is absolutely necessary to observe the condition that the level of the warehouse’s lower floor should be appreciably, for example by 1.0–1.5 meters, above ground level.

As for the pipes in the roof that are usually adopted for unheated warehouses, these devices in fact serve to remove from the upper levels of the warehouse the air that is most heated and has a relatively low degree of humidity. Consequently, ventilation pipes of this kind lower the temperature of the upper part of the unheated warehouse, while removing from there excessively dry air and thereby contributing to a reduction in the degree of drying of the sugar stored in the warehouse at its upper levels.

According to Vasiliev’s data,¹) the drying of refined sugar during storage in warehouses ranges for the upper bags of stacks from 0.04 to 0.45% and even up to 0.625% by weight of sugar. Whereas in the same stacks, but in bags of the lower rows, a noticeable dampening of the sugar was observed at the same time.

As was established in the proper place, the space of an unheated warehouse turns out to be very unevenly heated not only in relation to its vertical section, but also in horizontal planes. With the low mobility of the air in the warehouse, with its separation by the mass of sugar in stacks, and with the usually very considerable volumes and areas of sugar warehouses, it is obvious that the outflow of cold air from them under such conditions may occur very unevenly throughout the space and area of the warehouse. Therefore, the removal of cold air from the warehouse can be carried out much more fully, expediently, and easily by gradually displacing it from above downward with relatively warmer air introduced from outside into the upper horizons of the interior space of the warehouse, in accordance with the hydraulic theory of gas motion advanced by Professor V. E. Grum-Grzhimailo²) for the calculation of metallurgical furnaces. The air of the upper half of the warehouse, gradually pushed down to the bottom of the warehouse, ...

¹) Z. B. O. 1910, p. 119; 1909, p. 1, etc.
²) The Flame Furnace by V. E. Grum-Grzhimailo. 1925. Moscow.

is admitted perfectly uniformly over the entire area of the storehouse, thereby completely displacing from it, from everywhere, the cold and damp air. The removal of air from the storehouse must be arranged from its very lowest levels.

Implementation, according to the indicated method, of the heating and ventilation of storehouses requires:

1) windows and doors in the storehouse that close hermetically, in the absence of any other openings, vents, or leaks in the walls, floor, and ceiling of the storehouse;

2) supply and exhaust ducts for the air;

3) fans or exhaust pipes for the air being removed;

4) heating devices for the incoming air, installed outside the working space of the storehouse, which must be entirely free of any calorifers, heating pipes, etc. With artificial ventilation of a storehouse of the indicated type, its lower floor under the sugar may be placed at any distance from the lower level of the basement and from the ground, which, as was established earlier, should not occur in storehouses with natural ventilation.

The results of the investigation carried out on the moisture content of sugars stored in 1925 in the Tomsk storehouses, as well as in general the practical data from unheated storehouses in Siberia—despite the generally negative results of this storage and the imperfection of the local storehouses—nevertheless definitely reveal the possibility of successful storage of a part of the sugar filling these storehouses without any caking of it. This circumstance is of very substantial importance both for clarifying the question of the possibilities of preserving sugar without heating and with respect to the construction of the storehouses themselves of this kind. In view of this, let us turn to the case of Tomsk storehouse of Sakhartrest No. 5 and determine from it what characterizes, in temperature terms, that space of the storehouse where the sugar that did not cake during storage was located. This is conveniently established from the data of the corresponding tables and from the diagrams of drawing III, expressing the temperature regime of the storehouse and its changes over time during the period from March to July.

The sugar that does not become damp during storage is located in storehouse No. 5, as in the other storehouses similar to it, on the floor of the second story, i.e. at a height of 4 meters from the bottom of the storehouse, in the space between this floor and the level lying 1.5 meters higher above it, with the temperature point of this level, characterizing it in the diagrams of drawing III, being situated in the storehouse two meters below its roof.

Comparing the temperatures of the levels delimiting the space of the storehouses that excludes dampening of the sugar stored here with the temperatures of the lower and upper levels of the storehouse, and comparing their successive changes with the temperature fluctuations of the outside air, it is possible to establish certain propositions that are significant for the question under consideration.

As can be seen from the diagrams, the zone of the storehouse space—let us, for brevity, call it the “non-dampening zone”—in temperature terms obeys everywhere the general course of changes in the temperature of the outside air. To random, relatively short-term and abrupt fluctuations of the outside air, this zone reacts to a significantly weakened degree, which accounts for its relative temperature stability. In addition, owing to its distance from the lower level of the storehouse, it relatively weakly perceives the cooling action of the ground, of the cold air sliding downward in the storehouse, and of the poorly heated sugar located here. The indicated zone is in the same position also with respect to the influence of the storehouse roof, which at times becomes very strongly heated, and at other times considerably cooled.

The chief factor mitigating the influence of external actions on the zone under consideration is its remoteness from the roof and from the floor of the storehouse,

lying directly on the ground. Therefore, everything that can weaken the temperature influence of both on the interior space of the warehouse must contribute to expanding its zone that does not become damp.

It is obvious that, with respect to the negative influence of the roof, such a means is the corresponding arrangement of the roof and the provision of ceilings for the warehouses. As for the means that soften the cooling influence of the ground, these are a cellar space and raising the stored sugar—or, more precisely, the floor for it—to a sufficient height above ground level.

In addition to all this, an important role must be played by the proper arrangement of air channels for the flow of cold air and for the extraction of excessively warm air from the interior space of the warehouses, which has already been discussed in the preceding exposition.

As for the necessity of artificial heating of the warehouse, it is not required for the indicated zone. At the bottom of the warehouse a deficiency of heat is felt, while at the upper levels heat proves to be in excess. Therefore, to avoid the drying out of the sugar, this heat must be removed from there through exhaust pipes in the roof. If this circumstance is taken into account and it is considered that even in rationally arranged unheated warehouses a certain, though smaller, difference between the temperatures of the bottom and the top of the warehouse will still inevitably be observed, then it will appear possible to eliminate this unevenness by combining the lower and upper layers of the warehouse air by mixing them, for example, with electric fans placed inside the warehouse and periodically put into operation as needed.

Everything set forth definitely reveals the necessity of rationalizing the existing unheated warehouses for sugar storage, which is especially necessary in Siberia. In this connection, the following principal features of the arrangement of unheated warehouses are indicated.

The lowest internal level of the warehouse must lie 0.5 meters above ground level. The floor for the sugar must rise above the level of the cellar space by 1.0–1.5 meters. The height of the working space is 3–3.5 meters. The floor beneath the sugar is made of wood, with one-vershok openings through every 2–3 boards, to allow cold air to drain into the cellar space and to allow free circulation between the cellar space and the space above the floor. The working space of the warehouse is covered by a ceiling. The roof must be arranged so that the space between it and the warehouse ceiling can be ventilated as needed by opening the appropriate attic windows, since the temperature of the attic space is just as important as the temperature of the warehouse cellar space.

The doors and windows of the warehouse, arranged in the most limited number, are to be placed exclusively in the northern or eastern wall.

The construction of doors and windows, as well as of all other openings leading into the warehouse space, must permit them to be closed hermetically, excluding any free penetration of air into the warehouse, apart from its inevitable natural ventilation through the walls, ceiling, etc., or artificial ventilation carried out in a planned manner through the air exhaust and inflow channels.

Exhaust pipes, evenly distributed in the ceiling, are led out above the roof and provided at the top with caps. Inflow air channels are placed at the lowest level of the cellar space and open in the outer walls of the warehouse 0.1 meter above ground level.

There must be no other vents, pipes, or other openings establishing free communication of the warehouse interior with the outside atmospheric air in warehouses intended for sugar.

The entire warehouse space must be divided into compartments completely isolated from one another with respect to communication of their air space, each compartment having a capacity of 5–7 wagonloads.

The last requirement follows from the established ease and rapidity with which sugar becomes damp. Therefore, if it is unavoidably necessary to open a storehouse for unloading sugar, often in weather not especially favorable for it, then, of course, care must be taken to protect the sugar remaining in the warehouse from the harmful influence of such weather. This can be accomplished only by dividing the common space of a large warehouse into mutually separated small compartments.

The presence of the latter also makes possible more convenient and thorough ventilation of the warehouse. With artificial ventilation, a divided warehouse requires a smaller power installation than an undivided one, since in a differentiated warehouse its ventilation can be carried out gradually, in sections.

Limiting ourselves to what has been said regarding the principal requirements for the construction of sugar warehouses, let us now turn to consideration of the question of their heating. The chief danger with respect to the dampening of sugar stored in a warehouse, as has already been established, lies in the lag of the warming of the mass of sugar behind the warming of the atmospheric air. Therefore the fundamental task of successful sugar storage in warehouses consists in constantly maintaining such a temperature difference between the sugar and the air as would exclude the possibility of the sugar sweating in the warehouse under the most unfavorable meteorological conditions.

It is obvious that this difference is determined by many circumstances. It depends not only on the temperature of the sugar and of the air, but also on the direction of the temperature changes, i.e. whether they are proceeding toward cooling or toward heating. In addition, the rate and amplitude of the fluctuations of the outside air, as well as the arrangement of the sugar-storage facility, are also of essential importance. In attempting to establish this difference, the extreme temperatures of the sugar in the warehouse and of the outside air are usually compared directly.

It is obvious that this is incorrect, since an unheated warehouse, even under severe Siberian climatic conditions, considerably narrows, for its internal space, the temperature amplitude of fluctuations of the outside air. And therefore the temperature difference threatening the sugar with dampening in reality proves to be much smaller than is usually assumed, as is clearly shown by diagrams of the temperature regime of the warehouse. In view of this, in analyzing the question of the dampening of sugar in warehouses one must proceed from a comparison of the extreme temperatures of the internal air space of the warehouse and of the sugar contained in it, and not from a comparison of the latter’s temperature with the limiting temperatures of the outside air. Under such conditions the problem of heating sugar warehouses is noticeably narrowed. If, moreover, one takes into account that the warming of the predominant mass of sugar stored in unheated warehouses—except for that located in the lower tiers under unfavorable conditions—nevertheless proceeds quite satisfactorily under natural conditions, following the general temperature changes of the atmospheric air, then it follows from this that heating of warehouses for the artificial warming of the mass of sugar stored here is not required.

However, in this connection there arises the question of the necessity of heating the warehouse in relation to its ventilation, i.e. the possibility, without heating, with natural or artificial ventilation, of removing from the warehouse all the moisture introduced there together with the outside air.

In considering the question of humidity and temperature in unheated warehouses, one should refer both only to the middle and to the upper spaces of modern warehouses. The corresponding conditions of their lower levels cannot be taken into account, as being quite abnormal in view of the already established incorrectness of the arrangement of these warehouses, leading

toward the accumulation and stagnation here of cold air, which disrupts the normal warming of the sugar and creates a locally elevated humidity.

In the case under consideration, no account is taken at all of moisture entering the warehouse through its walls, floor, etc., since quantitatively it is insignificant compared with the moisture mass of the air passing through the warehouse, which, under unfavorable conditions, may be retained there.

Atmospheric air in Siberia generally, and in Tomsk in particular, is comparatively rarely saturated with water vapor.

However, it is very often close to this state, namely at about 90–96% relative humidity, and at times for long periods, chiefly in autumn. In winter the relative humidity of the air also remains high. From February it begins to fall, reaching its lowest level in May and June, when on monthly averages it reaches 60–65%, with daily decreases in some days going even as low as 40%. After June the humidity of the air begins to rise again.

At the same time, however, it must be noted that during the period of greatest dryness of the air, its relative humidity repeatedly during the summer unexpectedly rises for a short time almost to the state of saturation. From the diagrams of Plate II (daily maxima and the corresponding temperature dew points, calculated from the mean daily relative humidity for Tomsk for 1925), it is evident that in autumn and winter the dew point is extremely close to the temperature of the outside air.

During autumn and winter the dew points of the atmospheric air, judging from the mean monthly data, lie below its mean daily temperatures by only \(2^\circ\mathrm{C}\), varying within the range from \(0^\circ\) to \(5^\circ\mathrm{C}\). Beginning in March, this difference rapidly increases, rising in June to an average for the month of \(8^\circ\), with daily fluctuations from 3 to \(14^\circ\). After June the dew-point temperature again gradually begins to approach the corresponding mean temperature of the atmospheric air. Thus, from the standpoint of the proximity of the dew point to the temperature of the atmospheric air, the danger of dampening for sugar stored in unheated warehouses is very great. From the standpoint of relative humidity, the possibility of dampening appears greatest in winter and autumn. However, if one pays attention to the absolute humidity of the atmospheric air in the different periods of the year, one must arrive at another conclusion, namely that quantitatively the danger of dampening of sugar is considerably greater in spring and summer than in winter. From the meteorological data for Tomsk it is evident that the absolute humidity of the air in winter fluctuates from 1.06 to 1.91 g, whereas in summer it rises to 12.40 g. If, moreover, one takes into account that in spring and summer there inevitably recur instances of an unexpected rise in relative humidity, although short-lived, but extremely high and not infrequently corresponding almost to the state of saturation, then it becomes obvious that, from the standpoint of the absolute magnitude of the possible dampening of sugar in a warehouse, the warm period of the year is the most dangerous time for sugar stored in warehouses. In general, everything just said indicates that the danger of dampening of stored sugar due to changes in the humidity of the atmospheric air is sufficiently great and, moreover, constant, irrespective of the time of year.

What significance, then, can unheated warehouses have for protecting the sugar contained in them against the negative effect upon it, at times, of excessive humidity of the atmospheric air?

The first and simplest possibility of using such warehouses in this respect consists in the complete isolation, for the time being, of their interior space from communication with excessively humid outside air. This can easily be accomplished, given the proper arrangement, by hermetically closing all windows, doors, air ducts, vents, and other connections of the inter—

interior space from the outside air. In such an isolated state the warehouse should remain until the excess moisture in the atmospheric air has disappeared. Of course, despite these measures, excess atmospheric moisture will nevertheless penetrate to some extent through the walls of the warehouse; however, this will still be far from what is produced by open vents, doors and windows that do not close tightly, etc. Unfortunately, this simple and entirely accessible measure is completely ignored in practice.

Being, to a certain extent, an accumulator of radiant solar energy, sugar warehouses, especially in spring and summer, gradually accumulate within themselves—apart from their lower levels, of course—a certain excess quantity of heat as compared with the surrounding air. This is easy to trace from the corresponding tables given earlier and from the drawing of the diagrams of the warehouse temperature regime. Under such conditions the air entering the warehouse from outside is here somewhat heated, which, in the case of high humidity of this air, lessens the danger of dampening of the sugar stored in the warehouse.

In addition to what has been noted, the significance of an unheated warehouse consists also in the mitigating action of its air space upon the perception, by the sugar stored here, of all external influences in general, including the influence of excessively moist outside air.

But despite all this, the protective significance of unheated warehouses against dampening of sugar proves, under a certain concurrence of meteorological conditions, to be insufficient in some periods of the year. Therefore, for the possibility of the unconditional preservation of sugar in warehouses, some means are necessary which would make it possible not only to prevent excessively moist outside air from entering the warehouse, but also to render it harmless and even make it useful for the sugar being stored. Such a means, as is known, is the heating of the outside air introduced into the warehouse. This heating must be to such a temperature and humidity as would exclude the possibility of the moisture contained in the air introduced here separating out in the warehouse. In individual cases it is even desirable, with this heated air, to remove the excess moisture accumulating in the warehouse. The latter requires only greater heating of the introduced air; consequently the whole matter comes down to heating the outside air admitted into the warehouse, the essence of which lies in lowering the relative humidity and increasing the moisture capacity of the air introduced into the warehouse under these conditions. By directing such air into the upper horizons of the warehouse and removing it from the lower levels of the latter, it is easily possible to displace entirely all the stagnant, excessively moist and too cold air present there and replace it with warmer, dry air.

With a certain duration of drawing the introduced, suitably heated air through the warehouse containing sugar that has begun to become damp, it is easy to dry the latter, as well as the warehouse premises themselves.

Thus there arises the necessity of installing, for every sugar warehouse, artificial ventilation with heating of the air introduced into the warehouse. Moreover, this ventilation should not be carried out continuously, but periodically, as needed. This need is established by a definite relation between the humidity and temperatures of the atmospheric air and the air inside the warehouse at its lower levels.

The indicated relation is determined, for the given temperatures and humidity of the outside air, by such cooling of it inside the warehouse at which the relative humidity of the outside air introduced here may rise to limits threatening the stored sugar with dampening. But, as has been explained, these limits are not constant and depend on the temperature and purity of the sugar.

For absolutely dry, pure sugar, the threatening humidity of the air surrounding it is \(111\%\). For solid pure sugar, however, having on

on its surface even the most minimal layer of a syrup made from chemically pure sucrose, the humidity of the air at which such sugar begins to become damp varies, depending on the temperature, within the limits of 91.3–89.2% relative humidity. For sugar that has already become noticeably damp, has lain for some time, and has undergone inversion in its syrup, the limiting humidity of the surrounding air, taken as before with a known approximation, varies from 77.9 to 73.5% relative humidity for temperature limits from 0 to 35°C.

The stated proposition shows that, in the rational servicing of a sugar warehouse, it is necessary to maintain in it a definite temperature and humidity, changing with the season, the weather, and the location of the warehouse. Under such conditions ventilation of the warehouse may be necessary at one time, wholly unnecessary at another, and, finally, positively harmful at still another. The criterion of its necessity, conditions, and degree is the humidity and temperature of the outside air and of the air inside the warehouse. Consequently, thermometers and instruments for determining humidity must be the obligatory and constant companions of every sugar warehouse, and concern for the systematic keeping of the corresponding logs must be included among the permanent duties of the supervisory personnel of warehouses. Without this condition, work in warehouses proves to be entirely unfounded and inevitably leads to greater or lesser spoilage of the sugar stored.

It is obvious that the procedure for airing and ventilating warehouses cannot be formulated in the form of some fixed program, everywhere and always obligatory, established according to conditions and time. However, there are cases when ventilation is unquestionably required; namely, it is always necessary after every opening of the warehouse, for example for unloading, loading the warehouse, etc. The reason for this lies in the fact that opening the warehouse, whether in hot summer or in cold winter weather, inevitably entails a disturbance of the temperature regime established in the warehouse, ideally completely uniform throughout the entire space of the warehouse. In connection with this there appears an unevenness in the temperature distribution, and along with it in the humidity, in the warehouse, which in some cases causes dampening, in others drying out of the sugar. Taking into account the rapidity and short duration with which the process of dampening of sugar develops, it must be recognized as necessary immediately after the opening of the warehouse to ventilate it until its regime is brought into a desirable and stable state.

It is self-evident that ventilation of sugar warehouses with heating of the air differs sharply in its essence from the usually recommended and practiced heating of warehouses, which aims not so much at warming the air of the warehouse as at warming the mass of sugar stored here and, partly, the warehouse building. In connection with this, heating pipes and calorifers are placed, when warehouses are heated, directly in the room with the stored sugar, which, in view of the essence of the processes of interaction between the stored sugar and the air surrounding it, is under these conditions a fundamental mistake.

An entirely different situation obtains in a warehouse with ventilation associated with heating of the air. Here neither the sugar nor the warehouse is artificially warmed, proceeding from the premise that, in the average course of their change over time, their temperatures without external intervention follow, with sufficient approximation, the mean temperatures and their changes of the atmospheric air. In this case only the air introduced into the warehouse is subjected to heating; from time to time it washes the internal space of the warehouse and the stored sugar. The purpose of this is to displace the cold air that sometimes stagnates here and to remove the accumulating excess moisture.

Accordingly, there should be no heating devices in the warehouse itself. The installation for heating the air and humidifying it, in the event of excessive drying of the sugar, must necessarily be arranged outside the working space of the warehouse.

It is clear that the indicated procedure for servicing sugar warehouses differs sharply from heating them in the commonly accepted practice, and not only in substance, but also with respect to the expenditure of heat.

This can be seen from a comparison of the quantities of heat required to warm the sugar and the air in a sugar warehouse. “If a warehouse contains 150,000 poods of granulated sugar, then to raise this quantity of sugar by \(1^\circ\text{C}\), according to Prof. Zuev,¹ about 1,000,000 calories are required, whereas to raise the temperature of the air contained in the said warehouse by \(1^\circ\text{C}\), only about 5,000 calories need be expended.”

In managing a warehouse, the decisive importance, as has already been explained, lies in establishing a certain relation between the temperature and humidity inside and outside the warehouse.

This relation, for given temperatures and humidity of the outside air, is determined by such cooling of the warehouse at which the relative humidity of the outside air becomes threatening for the dampening of the sugar stored there.

With regard to the limiting humidity of the air below which one should not descend in the warehouse, one may, with a certain approximation, accept the standards already indicated above.

As for the actual determination of the relative humidity of the outside air when it is cooled to the temperature of the warehouse, this is carried out by the usual calculation, leading to the generally known formula, presented below, for the relative humidity of cooled air. In this case the sought humidity is expressed by the ratio \(G/G_1\)—the weight quantity of water contained in one cubic meter of outside air in its corresponding state, to \(G_1\)—the quantity of water in one meter of saturated air at the temperature of the warehouse.

Where:

\[ \frac{G}{G_1} = \frac{pg}{g_1 \dfrac{(1+\alpha T)}{(1+\alpha t)}} \]

whence

\[ \frac{G}{G} = \frac{pg(1+\alpha t)}{g_1(1+\alpha T)} \]

\[ \begin{aligned} t &\text{ — temperature of the outside air.}\\ T &\text{ — temperature of the warehouse air.}\\ p &\text{ — relative humidity of the outside air at } t^\circ\text{C}.\\ g &\text{ — absolute humidity of the outside air at } t^\circ\text{C}\\ &\quad \text{in the state of saturation.}\\ \alpha &\text{ — coefficient of expansion of air.}\\ g_1 &\text{ — absolute humidity of the air in the state of complete}\\ &\quad \text{saturation at } T^\circ\text{C}.\\ \frac{1+\alpha T}{1+\alpha t} &\text{ — volume of 1 cubic meter of air at temperature } t\\ &\quad \text{after cooling it to } T^\circ\text{C}. \end{aligned} \]

The precipitation of dew from the outside air cooling in the warehouse begins at the moment corresponding to the case in which its relative humidity becomes equal to unity, i.e., when

\[ \frac{G}{G_1} = \frac{pg(1+\alpha t)}{g_1(1+\alpha T)} = 1. \]

Determining \(T\) from this equation, we find the temperature of the dew point in the warehouse.

The moment at which sugar begins to become damp in the warehouse occurs somewhat earlier, and moreover not identically, depending on the temperature, the purity of the sugar, the degree of its dampening, and decomposition.

¹ M. D. Zuev, Encycl. of Sugar Production, vol. IV, p. 334.

The temperature at which sugar becomes damp is determined by the following equation:

\[ \frac{p g (1+\alpha t)}{g_1 (1+\alpha T)} = K, \]

where \(K\) represents the value of the relative humidity of the air in the warehouse corresponding to the beginning of the moistening of the sugar here. Depending on the temperature, and also on the properties and condition of the sugar, the value \(K\), as has already been established, may fluctuate within wide limits from 91.3 to 73.5%, and in individual cases even down to 60%.

The formulas given make it possible, from the temperature and humidity of the outside air and the temperature inside the warehouse, to establish the limiting humidity of the warehouse at which the stored sugar will become damp. Knowing this latter value, one can, by the same equations, determine the corresponding temperature of the warehouse. Finally, these same formulas make it possible, from the temperatures and humidity inside and outside the warehouse, to establish the necessary temperature for the outside air introduced into the warehouse for the purpose of ventilating the warehouse premises. These calculations are very simple, but to carry them out it is necessary only to have at hand the well-known tables widely used in ventilation, heating, drying, etc. calculations, which give, for various temperatures, the numerical value of the binomial \((1+\alpha t)\), and also the value of the water content in a cubic meter of air in a state of saturation and at normal pressure. Below such a table is given for temperatures from \(-20^\circ\) to \(+35^\circ\) C, where, to facilitate computations, there is also introduced a column of numerical values for the product of the binomial \((1+\alpha t)\) by \(g\), the water content in 1 cubic meter of air at various temperatures.

Let us apply the indicated formulas and the data of the table given to some particular case from practice. Let us take from Table 20, for the Tomsk warehouse of Sakharotrest No. 5, its conditions corresponding to April 23, 1926. To simplify the calculations, we shall take the temperature readings in whole degrees. In the case indicated, the temperature of the outside air is \(+5^\circ\) C, its humidity 70%. The temperature of the warehouse at the level of the lower floor is \(+1^\circ\) C with a humidity of 94%. Is it advisable under such conditions to ventilate the warehouse by directly admitting the outside air onto the sugar of the lower story, for example, by opening the warehouse doors? This question reduces to determining, by the corresponding formula, the degree of humidity of the outside air at the temperature of the warehouse at the indicated level, which is expressed as follows:

\[ \frac{0.70 \times 0.0068 \times (1+\alpha \cdot 5)} {0.0045 \times (1+\alpha \times 1)} = \frac{0.70 \times 0.0069}{0.0045} = 1.08. \]

Since the value found is greater than unity, this shows that the outside air introduced into the warehouse at the floor level of the first story will begin to deposit a great deal of dew and thereby will cause the moistening of the sugar located there.

This example clearly demonstrates that the opening of warehouses, regarded as certainly useful, “on warm, clear, sunny days,” may often be knowingly conducive to the moistening and spoilage of sugar.

Thus, under the conditions of the indicated temperature and humidity, outside air must not be admitted into the lower part of the sugar warehouse. To what extent, then, is this possible for the upper part of the same warehouse, where the temperature is \(+12^\circ\) C? Here the outside air will assume the following humidity:

\[ \frac{0.70 \times 0.0068 \times (1+\alpha \times 5)} {0.0106 \times (1+\alpha \times 12)} = \frac{0.70 \times 0.0069}{0.0121} = 0.43\%. \]

TABLE 24.

Air temperature °C	Value	Water in 1 cubic meter of air, in kg	Product	Air temperature °C	Value	Water in 1 cubic meter of air, in kg	Product
$t$	$1+at$	$g$	$g \times (1+at)$	$t$	$1+at$	$g$	$g \times (1+at)$
−20	0.927	0.0011	0.0010	8	1.029	0.0083	0.0085
19	0.930	0.0012	0.0011	9	1.033	0.0088	0.0091
18	0.934	0.0013	0.0012	10	1.037	0.0094	0.0097
17	0.938	0.0014	0.0013	11	1.040	0.0099	0.0103
16	0.941	0.0015	0.0014	12	1.044	0.0106	0.0111
15	0.945	0.0016	0.0015	13	1.048	0.0113	0.0118
14	0.949	0.0017	0.0016	14	1.051	0.0120	0.0126
13	0.952	0.0019	0.0018	15	1.055	0.0128	0.0135
12	0.956	0.0020	0.0019	16	1.059	0.0136	0.0144
11	0.959	0.0022	0.0021	17	1.062	0.0144	0.0153
10	0.963	0.0023	0.0022	18	1.066	0.0153	0.0163
9	0.967	0.0025	0.0024	19	1.070	0.0162	0.0173
8	0.971	0.0027	0.0026	20	1.073	0.0172	0.0185
7	0.974	0.0029	0.0028	21	1.077	0.0182	0.0196
6	0.978	0.0031	0.0030	22	1.081	0.0193	0.0209
5	0.982	0.0034	0.0033	23	1.084	0.0204	0.0221
4	0.985	0.0036	0.0035	24	1.088	0.0216	0.0235
3	0.989	0.0039	0.0039	25	1.092	0.0229	0.0250
2	0.993	0.0042	0.0042	26	1.095	0.0242	0.0265
−1	0.996	0.0045	0.0045	27	1.099	0.0256	0.0281
0	1.000	0.0049	0.0049	28	1.103	0.0270	0.0298
+1	1.004	0.0052	0.0052	29	1.106	0.0285	0.0315
2	1.007	0.0056	0.0056	30	1.110	0.0301	0.0334
3	1.011	0.0060	0.0061	31	1.114	0.0318	0.0354
4	1.015	0.0064	0.0065	32	1.117	0.0335	0.0374
5	1.018	0.0068	0.0069	33	1.121	0.0354	0.0397
6	1.022	0.0073	0.0075	34	1.125	0.0373	0.0420
7	1.026	0.0077	0.0079	35	1.128	0.0393	0.0443

From the number found it is clear that, under the same conditions, the introduction of outside air into the upper part of the warehouse is quite possible and desirable.

Calculating in the same way the humidity of the outside air when it is introduced at subsequent levels of the same warehouse, we find the following values:

70% for the level of the floor of the second story, and

90% for a level 2 meters above the lower floor of the warehouse.

Consequently, outside air may be introduced here as well without fear of causing the sugar to become damp, which cannot be done with respect to the lower part of the warehouse. Meanwhile, cold and excessively humid air accumulates here and stagnates; its removal from here is necessary for the integrity of the sugar located here.

It is possible to remove from the warehouse these undesirable lower air layers not only by directly replacing them with outside air. They can also be eliminated by displacement with air already present in the warehouse, filling the overlying adjacent horizons. To accomplish this it is only necessary to introduce into the upper space of the warehouse relatively warmer air, taken from outside, in an amount equal only to the cold air removed from below; in doing so it will not come into contact at all with the warm outside air introduced into the warehouse.

Under such a condition, dew is no longer deposited at the lower levels of the warehouse, since the humid air, lowered from a height of two meters to the level of the first floor, will still have a relative humidity considerably below 100%, namely 88%. Thus, from what has been set forth it is evident that, despite the inadmissibility under the given conditions of ordinary ventilation of a cold warehouse with warm outside air, the use of the latter for ventilation is nevertheless entirely possible and expedient in similar cases; but for this it is necessary to introduce the warm outside air, without mixing it with the internal cold air, into the very upper horizons of the warehouse. Thanks to this, the cold and excessively humid air accumulating there is removed from the lower part of the warehouse, the temperature and humidity of the air space of the warehouse are equalized, and such a temperature regime is established as promotes the successful storage of sugar.

The totality of everything set forth above leads to the following general conclusions.

The primary cause of the dampening of sugar in warehouses is the stratification of the air in them into warm and cold layers under the influence of external temperature and meteorological changes.

The arrangements of sugar warehouses and the methods of caring for the sugar stored in them which do not take into account the phenomenon of air stratification in warehouses and do not allow for the rapidity and short duration of simultaneous dampening prove unsatisfactory and inevitably lead to dampening and subsequent spoilage of the sugar.

Sugar warehouses, being an intermediate factor in the interaction of sugar and atmospheric air, are, in their construction, order of servicing, and the success of storage, determined to a considerable extent by external climatic conditions. At the same time, some regions are favorable for the storage of sugar and for the construction of warehouses there, while others are not.

Siberia is little favorable for prolonged industrial storage of sugar there; therefore the customary single winter shipment thither of the entire quantity of sugar consumed by Siberia is inexpedient and requires review and alteration.

In the absence in Siberia of suitable sugar warehouses, with a shortage there in general of storage facilities fit for this purpose, and in the absence of proper management and supervision of sugar storage, the latter, during prolonged storage in Siberia, is inevitably doomed to spoilage.

In connection with this, unhealthy conditions are being created here for the marketing of sugar, while the many-million-strong Siberian population is deprived of a high-quality product of prime necessity, receiving instead sugar that is more or less spoiled, yellowed, lumpy, and often smelling musty.

As regards the current practice of marketing sugar, it must, to a greater extent than has been the case so far, be linked with the following provisions, which have practical and essential importance for the integrity of the sugar being marketed:

1) purer and drier sugar absorbs moisture at a higher humidity of the air, which makes it more stable when stored in warehouses;

2) the technical standards for the maximum moisture content of sugar depend on the lowest practically possible temperature for the given sugar;

3) the maximum moisture content of sugar sent to the northern regions, where prolonged winter frosts reach \(-20^\circ\) and more, must be the lowest and, for refined sugar, must not exceed \(0.10\%\) of its weight;

4) sugar sent to Siberia must possess the greatest purity and dryness.

In connection with the totality of everything discussed, the immediate tasks of the sugar industry of the USSR are:

1) a comprehensive and serious study of the question of the arrangement and servicing of warehouses for sugar;

2) a reconsideration of the question of supplying Siberia with sugar with respect to the conditions and timing of its shipment there;

3) an experimental study of the operation of warehouses and their temperature regimes both in general and, in particular, in Siberia;

4) revision of the existing instructions for storing sugar in warehouses.

Appendix 1.

CIRCULAR.

To all our offices and branches.

Below, for guidance and implementation, is communicated the Instruction on the storage and transportation of our sugars.

Member of the Board
Head of the Sales Department

INSTRUCTION (Sakharo-Trest)

on the storage and transportation of our sugars, of November 23, 1924

1. The technical warehouse must meet the following requirements.

I. The premises must be in fully good order, especially the ceilings and roof; preferably stone, with a wooden floor.

II. It must have sufficient capacity and floor load-bearing strength, as established by technical supervision.

III. Not damp.

IV. Having a sufficient number of exits convenient for carrying sugars.

V. Ventilated.

VI. Safe with respect to fire and natural disasters, such as flooding, etc.

VII. Safe from robbery.

VIII. Guaranteed, as far as possible, against rodents.

1. It is desirable to have the warehouse near railway stations, and, at steamboat piers, with an access railway track.

2. Sugar must be stacked on dunnage one quarter from the floor, separately by grades, in carload stacks; the height of lump refined sugar, sawn, pressed, should be no more than 6 sacks; chopped loaf sugar, 7–8 sacks; and white granulated sugar, 8–10, depending on the container, in straight rows, so that it is possible to walk around the carload stack and count the number of sacks.

Raw and wetted sugar must be stored separately from the rest of the mass of sugars.

Sugar arriving in defective containers must immediately either be poured into sound containers, or the container must be repaired.

All restacking of sugars must be avoided.

Note: The dunnage must consist of the following: thick beams 4–6 vershoks, with boards 2–3 vershoks placed on them; all this is covered with tarpaulin or old sacks or dense matting.

1. Refinery molasses must be in such a place where the sun’s rays penetrate less. In summer the barrels should be covered with a layer of straw, and mats placed on top; on hot sunny days, the mats and straw should be periodically sprinkled with water.

The soundness and condition of the barrels are checked from time to time by specialist coopers.

1. The warehouse must be regularly ventilated. On clear, dry, sunny days windows and doors should be opened, for which purpose they must have grilles.

The following shrinkage allowance is permitted:

For refined sugar, 0.025% (10 f. per carload).
For white granulated sugar, 0.04% (16 f. per »).

Figure 1.

METEOROLOGICAL DATA FOR THE CITY OF TOMSK

Daily minimum and maximum relative humidity and temperature in °C for 1925, and mean absolute and relative humidity and temperature for the period 1875–1910.

Months: January · February · March · April · May · June · July · August

Upper graph: humidity

• Daily maximum relative humidity
• Daily minimum relative humidity
• Daily relative humidity
• Mean absolute humidity by month for the period 1875–1910

Scale markings shown: °C; %

Selected plotted values visible on the curve: 106.2; 1.17; 1.91; 3.29; 5.51; 8.65; 12.40; 10.90.

Lower graph: temperature

• Daily maximum temperature
• Daily minimum temperature
• Daily temperature for 1925

Scale markings shown: °C; %

For the article by Prof. S. V. Lebedev.

Temperature and average monthly [[unclear: continuation of heading]]

August — September — October — November — December

10 · 20 · 31 · 10 · 20 · 30 · 10 · 20 · 31 · 10 · 20 · 30 · 10 · 20 · 31

Month

% · °C

Average monthly relative humidity for the period 1875–1910.

Average monthly temperatures for the period 1875–1910.

[[unclear: caption along lower edge: “Butyric-acid fermentation at Krasnaya … Russian-Center and Obukh. No. 8.”]]

To the article by Prof. S. V. Lebedev.

DIAGRAM

of the temperature regime of a sugar warehouse in Siberia (Tomsk) and its change over time during 1926.

Date
°C

March — 1, 10, 20, 31/1
April — 10, 20, 30/1
May — 10, 20, 31/1

Atmospheric air humidity at 2 o’clock in the afternoon.

54%, 54%, 57%, 56%, 70%, 84%, 34%, 42%, 58%, 44%

Designation of the temperature curves:

a — at a height of 2 m from the floor of the second story and 0.5 m from the roof.
b — at a height of 1.5 m from the floor of the second story.
d — at the floor level of the second story.
e — at a height of 2 m from the floor of the first story.

m —
n —
e —

[[unclear: cropped title fragment]] (city of Tomsk) and its changes by

Chart II.

Humidity.

May — 10, 20, 31
June — 10, 20, 30

Humidity.

Visible plotted percentage labels include: 67%, 57%, 58%, 51%, 61%, 57%, 58%, 100%, 86%, 95%, 88%, 100%, 94%, 94%, 100%, 54%, 42%, 58%, 44%, 51%, 51%, 61%, 47%, 60%.

Legend:

• m — flooring of the 1st story.
• n — at the floor level of the 1st story.
• c — air temperature.
• [[unclear: line designation]] — floor of the 2nd story.
• [[unclear: line designation]] — 2 arshins from the floor of the 1st story.

To the article by Prof. S. V. Lebedev.

DIAGRAM

of daily maxima and the corresponding temperatures of the dew points in °C for 1925 in Tomsk, calculated from the mean su[[unclear: continuation cut off]]

Vertical scale: °C, from \(+30\) to \(-30\).

Horizontal scale: days of the months:

January — February — March — April — May — June — July — August.

Legend:

— Temperatures of the daily maxima
— Temperature of the dew points

Curve labels visible on the diagram: А, Б, В, С, Д.

Drawing III.

[[unclear: beginning of title]] relative humidity.

°C

September | October | November | December

Mean monthly value of daily temperature maxima

Mean monthly value of temperature dew points

dew point

1. According to data from the Chronicle of N. Obs., the works of G. K. Tyumentsеv, and current reports of the meteorological station of the Tomsk Technological Institute. ↩↩↩↩↩

2. Proceedings of K.O.I.R.O., 1905, p. 279. ↩↩↩

3. Sucrerie belge 1899–1900, p. 492. ↩↩↩

4. Vogryzek, Chemistry of the Sugar Industry, p. 502. ↩↩↩

5. Proceedings of the Kiev Department—1903, pp. 81 and 107; 1905, p. 275. ↩↩↩

6. Ver. Ztschr. 1901, p. 453. ↩↩

7. Transactions of the K. O. 1905, p. 361. ↩

8. Oester. Ver. Zeitschr. 1901, p. 198. ↩

9. Transactions of the T. Society 1903, 8, p. 107. ↩

10. Ibid., 1905, p. 275. ↩