Nov., 1918
T H E J O U R N A L OF I N D U S T R I A L A N D E N G I N E E R I N G C H E M I S T R Y
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REFERENCES 1. Annuaire du Journal des M i n e s de Russie, St. Petersburg, 1840-5. 2. “The Industries of Russia, Manufactures and Trade,” World’s Columbian Exposition at Chicago, 1893. 3. Freidrich Matthai, “Die Industrie Russlands,” Leipzig, 1873. 4. Gornozavodskaia promyshlennost, Rossiia, St. Petersburg. 5. Bernhard Neumann, “Die Metalle,” Halle a/S, 1904. 6. T h e Mineral Industry, New York, 1892-1916. 7. Obshchii obzor glavnykh otraslei gornoi i gornozavodskoi promyshennosti, Petrograd, 1915. t 8. Obror vnieshnei torgovli Rossii, St. Petersburg (Petrograd), 1866-1915. 9. Maurice Verstraete, “La Russie industrielle,” Paris, 1897. 10. The Russian Year Book, London, 1911-5. 11. Sbornik slatisticheskikh sviedenii $ 0 gornoi chasti, St. Petersburg, 1864-7. ! *. 12. Statislicheskiia tablitsy 60 govnoi promyshleunosti Rossii, St. Petersburg, 1879. 13. P. von Winkler, Gornyi Zhurnal, 1893, pp. 578-611. BUREAUOR SOILS DEPARTMENT OF AGRICULTURE WASHINGTON, D. C.
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THE PREPARATION-OF SEVERAL USEFUL SUBSTANCES FROM CORN COBS1 By F.!B.
LAFORGE AND C. S. HUDSON
It has been shown by Hudson and Harding* that corn cobs yield about 12 per cent crystalline xylose through acid hydrolysis. The strength of acid employed was 7 per cent sulfuric and the hydrolysis was carried out by several hours’ boiling. We undertook to determine whether this acidity could not be decreased considerably by carrying out the hydrolysis a t a higher temperature in an autoclave. This proves to be possible with an acidity as low as 1 3 / ~ per cent at a temperature of 130’~ and there is thereby opened up a way for the preparation of crystalline xylose on a commercia1,basis. I t was noticed that a volatile acid is produced in noteworthy amount along with the xylose during the hydrolysis of thekcorm cobs, and the identification of this acid as acetic indicates that it may be a valuable by50 100 200 product in the preparation of xylose from corn cobs. A strength I 300 I Versfs of I to 2 per cent sulfuric acid appears to be necessary in order MAPOF THE MININGREGIONOF THE UWLS (Copied from an Official to obtain a good yield of xylose. If the acidity is lower there Russian Map) is little sugar produced, although a considerable quantity of Borders of governments - - - - Rivers -Railroads -- -Platinum mines the corn cobs passes into solution. Indeed, there may be extracted from corn cobs by water alone, a t the somewhat higher in 3 mines; in the Iuzhno-Zaozer district in I mine; in the Lialia temperature of 140’ to 160’, a water-soluble gum which is probacrown area in I mine; in the Znamen crown area in 3 mines; bly a Form of xylan. However, its hydrolysis by acids yields and there was I mine on the land of the peasant owners. The xylose in only moderate proportions, accompanied by a sirupy decrease of output for 1913and 1914for this district was caused mother liquor which does not crystallize. It was therefore by the curtajlment of work by the starateli since they have been, sought to remove this gum from the corn cobs by water digesin the places formerly worked by them, gradually replaced by tion in order that the subsequent acid hydrolysis of the residue dredges. Thus the yield of platinum diminished by 3,950 might yield xylose with a smaller proportion of uncrystallizable ounces in 1914. This decrease fell entirely on the mines of the sirup. This has proved possible and in addition it has been Nikolae-Pavdinsk district, where in the beginning of operations found that the gum has excellent properties as an adhesive for 1914the work of starateli was stopped altogether. These had which render it a useful product. The solid residue that reformerly produced most of the platinum obtained. Dredges ob- main9 from the corn cobs after acid hydrolysis consists printained 2,370 ounces of the platinum output in this district in 1914. cipally of cellulose. It is very absorbent and might be used as an In the Cherdyn district arelocated the mines of Prince Abaingredient in molasses, stock feeds, possibly also as an absorbent melek-Lazarev, which are situated on the Mala and Bolshaia for nitroglycerin in the manufacture of dynamite, and for other Kos’va rivers (Little and Big Kos’va) and the Tylai, as well such purposes. It has been found that it is readily gelatinized by as the mines of four “possessors,” Count Stroganov, Count 70 to 75 per cent sulfuric acid and may then be hydrolyzed to Balashev, Prince Golitzen, and Prince Abamelek-Lazarev, glucose after dilution with water, according to well-known located in the Verkh-Iaiven area. The output of the district methods. The glucose so produced crystallizes well and could decreased from 1912 to 1914,though the same mines were doubtless be used in the same ways that crystalline glucose worked in 1913 and 1914. The decrease of yield was shown from starch is employed. The manufacture of alcohol by the by all the mines except the Mala-Kos’vin belonging to Abamelek- fermentation of corn-cob glucose appears possible provided Lazarev. sulfuric acid is obtainable cheaply. I n the Iuzhno (South)-Ekaterinburg district the output of Direct uses for xylose, as such, seem difficult to find. Its platinum is very small. Besides that recovered in this district possible food value needs investigatien because it is probably there was also an insignificant quantity of platinum (3.7 ounces) 1 Contents of Address presented before the New York Section of t h e secured in the Sievero-Ekaterinburg district as a by-product American Chemical Society, May 10, 1918, by F. B. LaForge. in working the gold mines. * J . A m . Chem. SOC.,89 (1917), 1038.
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T H E JOC'RAVdL O F I N D C S T R I A L A N D E i V G I N E E R I N G C H E M I S T R Y YoI.
oxidized to some extent, especially by herbivorous animals, but the limit of tolerance is not known. Xylose is about half as sweet as cane sugar. Its after-taste is not bitter, as is that of mannose, for instance, and if uses for xylose as human food could be established its taste is in its favor. It is well known that xylose may be converted by the cyanhydrin synthesis to gulonic lactone. We would call attention to the suggestion that such lactones of the sugar group may furnish an excellent material for use as a crystalline acid ingredient in baking powders. Gulonic lactone stands out prominently as suitable for such uses, because of its ease of crystallization and the fact that it can be produced fairly cheaply from xylose. We have made experiments with mixtures of gulonic lactone and bicarbonate of soda and find that a very satisfactory baking powder may be so prepared. The preparation of gulonic lactone from xylose has been made by a method that is more satisfactory than that usually employed. It will be described in a separate paper by one of us (I,.). We will now describe in detail the preparation from corn cobs of the various usefu1 suhstances that have been mentioned. PREPARATION O F ADHESIVE GUM
The coarsely broken cobs are placed in an autoclave with sufficient water to cover them. The contents are then heated to 140', and the temperature then raised to 160' during one hour. After cooling below the boiling point of water the autoclave is opened and the contents removed. The liquid in the autoclave is almost fully absorbed by the dry cobs in the process of heating. The next step consists in the extraction of the solution from the solid residue in which it is absorbed; this is accomplished by subjecting the wet material to strong pressure. The solution thus obtained is evaporated in an open kettle to the consistericy of a thick sirup, which constitutes the adhesive gum. It is ready for use without further treatment, and is recommended as a cheap adhesive in the fiber board and paper-box industry, in bill posting, labeling, etc. The use of this substance in place of starch, dextrine, and flour paste would make possible an enormous saving of these foodstuffs. The solid residue which is left in the press Serves for the preparation of other products which are described below. PREPARATION O F XYLOSE AND ACETIC ACID
For the preparation of the sugar, xylose, and of acetic acid the residue from the preparation of the adhesive gum is treated as follows : An autoclave, such as was used in the preparation of t h e adhesive, is filled to about three-fourths of its capacity with the solid residue from the pressing operation above referred to. A solution of sulfuric acid containing about one and threequarters per cent of acid is added in sufficient quantity to cover the solid material in the container. Heat is then applied and the temperature of the contents of the apparatus raised to 130' C. where it is maintained for one hour. This treatment causes the liberation and solution of xylose and acetic acid. After cooling, the contents df the autoclave are removed and subjected to pressure to expel the solution from the undissolved solid material. This solution is then heated in contact with a second charge as before and thus a solution containing approximately double the amounts of xylose and acetic acid in a given volume is obtained. To isolate the acetic acid from this solution some of the steam from the heated autoclave is allowed to escape through a condenser and the distillate collected. This weak solution of acetic acid may be built up or fortified by causing it to pass through several such operations as just described, using the weak acetic acid solution instead of water as in the first instance. In this manner more and more acetic acid is accumulated in a given volume until the desired strength of acid is reached. This concentration may be made t o attain j or 6 per cent.
IO,
SO.I I
The xylose solution remaining in the autoclave after the second heating operation is separated by pressure from the solid residue in which i t is absorbed and from this solution the sugar is obtained. To accomplish the isolation of the xylose the snlution referred to is evaporated under diminished pressure to a thick sirup which is seeded with xylose and left for itself for In order to obtain crystals of sufficient size about 1 2 hours. to separate from the mother liquor by means of a centrifuge the following conditions must be observed: First, the solution should be concentrated without undue delay; second, the proper consistency, which is about that of ordinary commercial molasses, should be attained; third, crystallization should take place a t a temperature not lower than 20' nor higher than 35 ' C.; fourth, after crystallization has been induced by seeding, no more sirup should be added to the magma. The solid residue from the pressing operation.; above referred to, which consists chiefly of crude cellulose, may be used in the preparation of stock feed. For this purpose the press cake is coarsely ground, mixed with a small amount of lime or soda to neutralize the slight amount of sulfuric acid which it contains, and in this state is mixed with any desired amount of molasses or other sirup and dried by any suitable means. Such a mixture, if fed in connection with seed press-cake meal, mayconstitute cheap and good feed for cattle or other animals. A second use to which the crude cellulose residue may possibly he put is that of an absorbent for nitroglycerin in the manufacture of dynamite. For this purpose the material must be purified by washing with dilute caustic soda to remove a brown material present as an impurity. The excess of the reagent must be removed from the cellulose by washing with water. The cellulose may also be of use in the manufacture of artificial silk, leather substitutes, filaments, and plastics, by any of the processes now in common use. Other uses to which the impure cellulose residue may be put are the manufacture of -ducose and of alcohol. pREpARAT1oN
OP
CRUDE
CELLULoSB
The residue of impure cellulose above referred to, from which gum and xylose have been removed as already described, is ground to a rather fine powder and intimately mixed with about an equal weight of sulfuric acid of about 75 per cent strength. In determining the strength of acid to be used allowance should be made for the small amount of moisture left in the cake after the pressing operation. The resulting mixture is a stiff dough which is black in color. After the "dough" has been allowed to stand a t room temperature for about 6 hrs., it is mixed with a convenient amount of water (5 to 8 parts), and the mixture is boiled for about one hour, after which the undissolved solid residue is removed from the very slightly colored solution by means of a filter press. Slaked lime which has been sifted free from lumps and suspended in water is added to the filtrate in quantity sufficient to very nearly neutralize the free acid in the solution. The calcium sulfate which separates out on this treatment is removed by means of a centrifuge or filter press. The solid residue of calcium sulfate is washed with water and the washings are added to the filtrate. The resulting liquid is a dilute solution of glucose. This solution is added to a second portion of ground press cakewhich has been treated with sulfuric acid as above described and the subsequent operations of boiling, filtering, etc., repeated as before. This process may be again repeated until the sugar content of the solution has been increased to the desired degree. In order to isolate the glucose in the crystalline state the final solution is exactly neutralized with lime, filtered, and concentrated to a thick sirup. This sirup soon crystallizes to a solid mass. Glucose prepared after this manner has a slight brown color but is free from any objectionable taste and can be used directly as an ingredient of stock feed.
Nov., 1 9 1 8
T H E JOURNAL OF I N D U S T R I A L A N D ENGINEERING CHEMISTRY
In case the product were to be used for human food, very pure sulfuric acid and lime would have to be used in this preparation and decolorizing carbon or bone char would doubtless have to be employed. The glucose solution above referred to is very rapidly and completely fermented by yeast and hence could be used for the production of alcohol. By the process above described, about 50 per cent of the weight of the crude corn-cob cellulose is converted into glucose. The solid residue from the ‘first treatment of the material which was removed by the filter press, may again be subjected to digestion with 75 per centsulfuric acid, as was the original material, and again a yield of 50 per cent of its weight of glucose may be obtained by the above process, making the total yield 75 per cent, or 3 7 . 5 per cent of the weight of the corn cob. From two tons of sulfuric acid of the above-mentioned strength one ton of glucose could be prepared. In order to compete with glucose or molasses from other sources for the manufacture of alcohol, sulfuric acid of 75 per cent strength would have to be obtained a t a price not much greater than $8 .oo per ton. CONCLUSION
While the methods for obtaining these principal products from corn cobs have not as yet been tested out on a large factory scale, they can be said to be already out of the laboratory stage, since the work has been carried on by means of autoclaves, powerful presses, vacuum stills, centrifuges, etc. The yields of the various products constitute approximately the following percentages of the weight of the dry corn cobs: PRODUCT Adhesive G u m . . ........................ Crystalline Xylose.. ..................... iZcetic A c i d . . ........................... Crystalline Glucose.. ....................
Per cent 30 5 2 . 5 to 3 37
The United States is theworld’s greatest producer of corn. Our annual crop ranges from z 1 / 2 to 3 billion bushels, and represents nearly 75 per cent of the world’s production. Other couxtries which rank as great corn producers are Austria-Hungary, Mexico, Argentine, and Italy. For every bushel of corn there is approximately a bushel of cobs which, however, weigh only one-fourth as much as the grain. Corn cobs are not utilized to any great extent. They have a certain value as fuel and also have been used as an ingredient of stock feeds. They contain, however, little or nothing that is directly available for animal nutrition. They are one of the great waste products of our agriculture. We believe, however, that the methods of utilizing them which have been described in this article may eventually render them a valuable source of raw material for manufacturing. CARBOHYDRATE LABORATORY, BUREAU OF CH~ATISTRY DEPARTMENT OF AGRICULTURE WASHINGTON, D. C.
STATISTICS OF GARBAGE COLLECTION AND GARBAGE GREASE RECOVERY IN AMERICAN CITIES BY RAYMOND PEARL Received August 28, 1918
I n July 1917,the writer inaugurated in the Statistical Division of the United States Food Administration a system of voluntary statistical returns from the leading cities in the country, regarding the amount of garbage collected monthly and, where possible, the amount of grease recovered from the garbage collected. The purpose underlying the plan was to obtain information which would serve the officials of the Food Administration as an index of the effectiveness of their propaganda campaign urging the people to avoid waste in the preparation and use of food. In view of the somewhat novel character of the statistical material which has been collected in this work, it seems desira-
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ble to give it permanent record by publishing it where it will be available to public health officials and others who may be interested. Accordingly there is presented here the records of two complete years, from May 1 9 1 6 to April 1 9 I 8, inclusive. The statistical material was obtained through the voluntary cooperation of municipal officials. I n the first instance the mayors of all the larger cities in the country were asked if they would not arrange to have the proper official in their municipalities make a monthly report to the Food Administration on -the amount, in tons, of garbage collected each month in the current year and the corresponding month of the previous year, beginning with May 1917. The response was very gratifying, particularly in regard to the willingness, not to say eagerness, to cooperate, of those asked. In a rather considerable number of cases it developed, apparently quite as much to the astonishment of the city officials as to ours, that the city had no record, nor any ready method of finding out how much garbage was collected in that city in a given interval of time. Finally, however, we were able to get 9 6 cities, with an estimated aggregate population of over 26,000,000 reporting regularly and for each month in the z years from May 1 9 1 6 to May 1918. These cities include roughly about one-fourth of all the people living in this country. The numbers are sufficiently large to give considerable trustworthiness to the data as indicative of urban conditions in the country in general. The statistics are certainly much more comprehensive in their scope than any garbage statistics for the United States that have hitherto been brought together, so far as the writer is aware. At the end of the year a tabulation of all the monthly returns which had been made was returned to the reporting city official for verification or correction. In this way i t is believed that the figures here given are accurate so far as concerns the reporting of the municipal records. The original records themselves in some cases obviously do not include the whole of the garbage produced. In a few they are grotesquely far from the mark. 300
260
h
ZOO
1 e 0
8
3
z
100
L 50
0
FIG. I-THE
GARBAGE PRODUCTION, BASEDog RETURNS FROM 96 LAROEST CITIES
S E A S O N A L C U R V E OF AVERAGE
It is, for example, inconceivable that the hundred odd thousand people who live in Nashville, Tenn., produce only about 400 tons of garbage in a year, while about an equal number, say 10,ooo fewer, of people living in Norfolk, Va., produce in the neighborhood of 30,000 tons in a year. The fact is that the figures given in this paper refer to tonnage of garbage officially coElected either by or under the official control of the municipality so that the amount is a matter of city record. Only in cities where by ordinance it is forbidden to dispose of garbage in any other way than by delivery to the organized official collecting agency of the city can the statistics here given be regarded as representing the total amount produced.
