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organisms mentioned above. These were incubated a t 37’ C. for 48 hrs. a n d examined microscopically for increase in number of organisms. I n every case all grew very readily. The results obtained from t h e bacteriological investigations were entirely negative. I n a very few cases a mold developed on t h e plates a n d in one case a spore-forming organism developed. I n no case did we find growth in fermentation tubes or deep agar or milk cultures. Stained slides were made from fermentation tubes in many cases, b u t no organisms were seen. No organisms were ever noted upon slides made directly from t h e cans. About 50 g. of this material from I O different brands were fed t o white rats. They a t e most of this in two days; after t h a t t h e y were kept for three weeks on ordinary feed, but failed t o develop symptoms of a n y sort. EXAMINATION FOR TIN
Twenty of t h e above samples were analyzed for their tin content. These included t h e best and cheapest brands on t h e market a n d were picked a t random without a n y reference to their quality. Tin determinations were made according t o Journal of OJicial Association of Agricultural Chemirts, Vol. 11, No. 2, page 173. All tin determinations ran below jo mg. per kilogram, showing t h e y were well below t h e tolerance of 300 mg. per kilogram. C 0 N C LU S I 0 l iS
Canned salmon as found on t h e market in this state is sterile. It does not contain organisms of B . paratyphoid type, a n d does not contain aerobic or anaerobic spore formers. This is t o be expected if t h e packers process their goods according t o advertising material which they publish. I n one case t h e y claim t o heat t h e cans t o 220’ F. for 50 mins., followed by a heating t o 240’ F. for 60 mins. on a second day. This is necessary t o protect t h e packers against loss of goods after i t has been p u t on t h e market. From t h e fact t h a t this material will readily support t h e growth of pathogenic a n d other microorganisms, great care should be exercised in handling it after removal from t h e can. KANSASSTATEAGRICULTURAL COLLEGE MANHATT.4N KAXSAS
THE INDUSTRIAL CHEMISTRY OF CHICLE AND CHEWING GUM1 By
FREDERIC DANNERTH
The official estimate of chicle imported and converted in t h e United States in 1916 approximated 7,347,000 lbs., equivalent t o a t least 30,000,000 lbs. of chewing gum. An industry which has assumed these proportions may well be said t o exert a n influence on our national life. The retail selling price of t h e finished article is at t h e rate of S I . 30 per lb., from m hich some idea of t h e financial strength of t h e industry may be obtained. 1 Presented a t the 54th Meeting of the American Chemical Society. Kansas City, April 10 to 14, 1917.
679
I n view of this i t has become necessary t o establish standard methods for t h e purchase of the Crude Block Chicle. As i t arrives a t t h e port of New York or New Orleans i t contains a considerable amount of moisture-usually about 40 per cent. The factors which influence t h e purchaser may be summarized as follows: (I)-The moisture t h e gum is estimated t o contain. (a)-The shrinkage when cleaned (dirt a n d bark). (3)-The chewing quality of t h e clean purified chicle. (4)-The color of t h e crude chicle. MOISTURE
The amount of moisture contained in crude chicle was until very recently ascertained in t h e course of factory operations. For example, a Ioo-lb. lot was chopped up into ‘/*-in. crumbs a n d dried in a hot air chamber. T h e loss of weight was recorded as moisture. A somewhat better idea of t h e value of t h e chicle can be obtained by proximate analysis. T h u s one sample of Yucatan chicle when examined in t h e laboratory showed: Per cent Acetone-soluble matter (resins), . . . . . . . . . . . . . . . . 40 .O Gutta (and carbohydrates). 17.4 Proteins.. ................. 0 . 6
.
Per cent
. . . . . . 35.0 2.3 ........ 4 . 7
Sand and foreign matter. Water.. ..................... Mineral matter (ash)..
Obviously, if this chicle costs $ 0 . 5 5 per lb., crude, its value is $0.877 per lb. after drying and cleaning. I n other words, IOO lbs. of crude chicle in this case yielded 6 2 . 7 lbs. of dried and cleaned chicle. sAawL1Kc-h sampling crude chicle after i t has arrived a t t h e factory a I-lb. sample is cut from a block. This is cut up into ‘/*-in. crumbs just as rapidly as possible. The crumbs are transferred t o a “Lightning Jar” provided with a glass lid and rubber gasket. The jar should be not more t h a n two-thirds full, leaving room for a thorough mixing by shaking t h e contents, a n d should be kept in a cool place t o prevent caking. T h e large amount of moisture usually present in crude chicle makes it imperative t o handle t h e sample rapidly. Wet chicle cannot be stored in sealed jars for more t h a n one week as molds grow rapidly, especially if t h e jars are kept in t h e dark. M E T H O D I-A weighed portion of crude chicle (about 5 g.) is dried in a well-ventilated air b a t h for 5 hrs. a t a temperature not above 50’ C. As a container for t h e sample, a glass dish 2 or 3 in. in diameter with a ground glass lid is used. If t h e temperature in t h e oven rises, fusion will occur a n d evaporation of t h e water will be retarded. If t h e oven is poorly ventilated t h e drying will take longer. It is complete when two consecutive weighings vary not more t h a n 0 . 5 per cent. M E T H O D 11-The moisture in crude chicle may be determined simultaneously with t h e determination of resins. Boiling acetone will remove resins a n d water from t h e sample by extraction. The extract in t h e flask is dried at 105’ C. a n d t h e residue in t h e thimble is dried in a similar manner. The sum of these weights subtracted from t h e weight of t h e
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original sample will represent water. This method has given very satisfactory results in practice. NoTE-If wet chicle is heated t o 105’ c. in a n oven, a certain amount of mosture is driven off, t h e chicle fuses and becomes “tacky” and if this product is chewed it will be found t o be quite rubbery. At such temperatures t h e gum undergoes a chemical change as is seen by its solubility in acetone and in alcohol. For these reasons the usual methods of determining water by heating in a n air bath a t 105’ C. are not applied in t h e analysis of chicle. As soon as a n a t t e m p t is made t o chop up a block and granulate t h e chicle, t h e gum commences t o lose water so t h a t due consideration must also be given this fact. VISCOSITY
The valuation of crude chicle by means of a viscosity test has, so far as I know, not been attempted by other investigators. This is probably due t o t h e fact t h a t it is very difficult t o prepare a fluid mixture which would not settle out. The results here presen’ted have been obtained by means of over 2 0 0 determinations a n d it is believed t h a t t h e method is of practical value. The solvents used experimentally for suspending t h e chicle included xylol, benzol, toluol, turpentine a n d kerosene. Kerosene (boiling point above 140’ C.) was finally chosen, as t h e loss by evaporation is negligible. Before proceeding with t h e test, commercial chicle must be dried for 1 2 hrs. in a vacuum a t a temperature not exceeding 70° C. ~ ~ E T H O D - ~ Og. of t h e dry chicle are weighed off accurately t o tenths of a g. and placed in a wire basket fitted in size for a “Joint Rubber Committee” extraction apparatus.’ I n t h e flask are placed 7 5 cc. of kerosene. The wire basket is made of Ioo-mesh wire gauze so t h a t it retains the gritty and fibrous matter with which commercial chicle is contaminated. The weight of t h e residue in the basket will give some idea of t h e percentage of foreign substances in the crude chicle. The liquid thus obtained by suspending strained chicle in kerosene is poured into a I O O cc. graduated cylinder. Fresh kerosene is now poured into t h e cylinder so t h a t t h e total volume will have a concentration of 2 0 g. of strained chicle in a total of IOO cc. of liquid. After cooling t h e liquid t o 20’ C. it is introduced into t h e small t a n k of a Stormer viscosime t e r e 2 The lower portion of t h e capsule of the viscosimeter is removed and filled with shot so t h a t t h e total weight of this lower portion of t h e capsule together with t h e shot is exactly 2 0 g. As a matter of convenience t h e records of viscosity may be kept in terms of Revolutions p e r minute. The weight is allowed t o fall for a definite number of seconds, taking care t h a t the total length of cord is never unwound. The upper surface of the rotating cylinder in the viscosimeter should be adjusted in such a position as t o be on a level with the upper edge of t h e projecting bracket in t h e t a n k which holds the test liquid. 1
THISJOURNAL, 9 (1917), 310.
*Seaton, Probeck and Sawyer, THISJOURNAL, 9 (1917), 35, have presented much interesting data on the viscosity of varnishes and the hmitations of the various viscosimeters.
Vol. 9 , No. 7
Mr. Charles Kernahan, of this laboratory, who has assisted me in many of these determinations, reports t h a t benzol appears t o be a desirable medium for suspending t h e chicle in t h e viscosity test. It has t h e advantage t h a t chicle may be boiled in it without exceeding a temperature of 8 1O C., thus precluding decomposition of t h e gum. The precaution which should be observed in t h e use of benzol is t h a t the test should be carried out in a room having a temperat u r e not much above 2 0 ’ C., as there will otherwise be a considerable loss of solvent by evaporation. ACETONE-SOLUBLE
MATTER
The extraction of rubber and related gums with boiling acetone is carried out principally for t h e purpose of determining t h e percentage of “resins” in t h e material. I n fact many analysts use these terms synonymously. T h e peculiar chewing properties of chicle are due t o t h e presence of these resins so t h a t a determination of their amounts and characters would seem t o be of paramount importance t o t h e industry. An idea of t h e resin content of t h e principal minor gums may be obtained from t h e following approximate percentages: Pontianak, 7 5 ; chicle, 6 0 ; g u t t a percha, 50; balata, 40; guayule, 2 0 . One of t h e principal properties of t h e resin which affects t h e chewing quality of the gum is its melting point so t h a t this should be determined in most cases. METHOD-If t h e acetone extraction is carried out without regard t o t h e moisture content of t h e chicle, t h e material is granulated so t h a t it will pass through a wire screen of ‘/s-in. mesh. Five grams of the material are accurately weighed out and placed in a folded filter fitted for a Soxhlet siphon cup. The apparatus used is t h e Soxhlet extractor of the Joint Rubber Committee.’ Acetone having a boiling point not higher t h a n 65’ C. is used and t h e extraction is continued for j hours. The acetone in t h e flask may be evaporated by placing t h e flask on a hot plate or it may be distilled off and t h e flask then dried t o constant weight in the oven a t a temperature not above 105’ C. It is finally cooled in a desiccator and weighed. The residue is dried a t 8j0 C. in t h e oven. The sum of t h e extract and t h e residue is now subtracted from t h e weight of t h e original sample. The difference is the moisture in t h e sample. If t h e acetone solution in t h e flask is allowed t o cool before i t is distilled off, it will be noticed t h a t a large part of t h e resins has separated out in t h e form of a wax-like incrustation. After all t h e acetone in t h e flask is expelled and t h e temperature reaches 105’ C. t h e residual resins appear amber-colored and quite clear. These resins are brittle a t room temperature. The residue of g u t t a on t h e filter should be dried a t temperatures not above 85’ C., as it otherwise readily carbonizes. This is apparently due t o t h e low “ignition temperature” of this gutta. I n 30 samples of chicle from Mexico, t h e resin cont e n t varied from 59.0 t o 6 3 . 3 per cent with a grand average of 60.8 per cent based on t h e dry chicle. Twelve specimens of dried chicle which had an aver1LOG
Ctt.
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T H E J O U R N A L OF I X D U S T R I A L A N D ENGINEERING CHEMISTRY
age resin content of 6 1 . 8 per cent were tested for viscosity according t o t h e method previously described. The results showed a n average of 276 revolutions per minute. Twelve other specimens which were examined showed a n average resin content of 6 0 . 0 per cent a n d a n average of 284 revolutions per minute. T h e rule then would seem t o be t h a t t h e R. P. M. is inversely proportional t o t h e resin content, or rather t h a t t h e viscosity is directly proportional t o t h e resin content. This was in fact found t o be t h e case for t h e particular conditions under which these determinations were carried out. PROTEINS-The peculiar character of vegetable proteins, their complex chemical constitution and t h e fact t h a t they do not crystallize all have combined t o retard t h e investigation of this constituent. Spence has given considerable attention t o these bodies so f a r as they occur in t h e rubbers prepared from Hevea, Funtumia a n d Ficus. I n a recent paper Spence a n d Kratz’ have proposed a method for t h e determination of proteins in washed a n d dried rubber and i t is planned by t h e present author t o a d a p t this method, if possible, t o t h e estimation of proteins in chicle.2 CARBOHYDRATES-PreViOUS investigators have SUggested t h a t t h e sugars contained in chicle may be related t o hexa-hydroxy-hexa-methylene. T h e monomethyl derivative of this sugar has a melting point of 192 O C. and is found in t h e latex of Hevea brasiliensis. Plantation crepe Hevea rubber contains from 2 . 0 t o 3 . 0 per cent of this substance. An investigation on t h e sugar content of various chicles is now in progress a t this laboratory. A paper on this subject was published b y Pickles and Whitfield3 as early as 1911. M I N E R A L MATTER
This determination is carried out with a sample of one gram, a n d in a n y case not more t h a n two grams of d r y chicle. An asbestos shield is used a n d a hole inserted so t h a t t h e crucible bottom is exposed t o t h e flame. At first a low flame is used so t h a t t h e organic matter can volatilize without catching fire. After all t h e carbon has been burnt off, t h e crucible is dried a n d weighed in t h e usual manner. Of 2 5 specimens examined, t h e lowest value obtained was 3 . 9 per cent a n d t h e highest was 5 . 9 5 per cent of ash. T h e grand average was 4 . 5 3 per cent of ash. I t will be noted t h a t this figure is much higher t h a n t h a t usuallykiven for t h e ash content of washed a n d dried rubber. The highest values recorded for rubber are I . o per cent for Funtumia. FERMEKTATIOS O F CRUDE C H I C I E
Mention should be made of t h e influence of fungi on crude chicle. These low forms of plant life do not a t tack t h e gum if it is kept in d r y air, b u t if a small amount of moisture is present, t h e molds begin t o flourish. Their nourishment is derived from t h e proteids, resins, a n d sugar which t h e gum contains. This results in a discoloration of t h e chicle, turning it 3
Spence and Kratz, Kolloid Z.,1914, 262. Beadle and Stevens, Analyst, January, 1912. Pickles and Whitfield, Proc. Chem. Sac., 27 (1911). 54.
681
pink or light buff in color, b u t i t is not materially altered thereby. On t h e other hand, certain species of Actinomyces which occur in garden earth a n d canals are capable of assimilating t h e chicle-hydrocarbon with t h e result t h a t its properties are so modified as t o alter its chewing quality very decidedly. T h e principal varieties thus far recognized are A . elastica a n d A . fustus. The fermentation of chicle is also induced by t h e presence of uncoagulated milk in t h e pores of t h e block. I n fact a piece of crude wet chicle, if chewed, will be found t o taste quite acid. IKDUSTRIAL RESEARCH
T h e methods of t h e chewing gum industry have up t o t h e present time been based largely on experience, b u t there is a distinct tendency toward a scientific study of t h e technical problems which arise. Some of these problems have already been successfully a t tacked a n d solved while others are still in a state of investigation. A review of these will be of value t o those interested in these gums: I-How can brittleness in the finished chewing gum be prevented? 2-HOW can the absorption of moisture by the finished gum be prevented? 3-What properties are most desired in a substitute for chicle? 4-Which is the best method for introducing flavors into a batch of gum? g--U’hat influence has heat on the chicle dough in the kettle? 6-What influence has the duration of the “cooking” on the dough in the kettle? 7--What influence have substitutes on the “keeping” qualities of the finished gum? %-What influence have temperature and moisture on the finished gum during storage? 9-What are the advantages of drying or moistening the air in chewing gum factories? Io-What relation has the resin content to the chewing qualities of the chicle? II-HOW can crude chicles be axeraged in order to secure a finished gum of uniform characteristics? Iz-What influence has the coagulation method on the quality of the crude chicle produced by th’e Sapoteros? 13-How can “stiff” chicles be softened and how can “soft” chicles be stiffened? 14-What influence have the several constituents of a chewing gum compound on the chewing quality of the finished gum? IS-HOW can the dirt and the bark be removed from crude chicle without destroying the desirable qualities of the gum? 16-How can low-grade chicles be improved? 17-K’hat relation has the viscosity of chicle solution to the chewing properties of the gum? 18-How can rubbers and related gums be converted into plastic gums suited for chewing? 19-Can chicle he strained while in a molten condition without altering the chewing properties of the chicle? 20-1s the protein content of chicle a detriment or an asset? APPENDIX
The Custom House statistics of the United States show that the gross imports of chicle and balata in 1 9 1 2 to 1916 were as follows : Year Lbs. chicle 1 9 1 2 . . , , , , , . . . . 7,782,005 1 9 1 3 . . , , , . , . , , , 13,758,592 1 9 1 4 . . . , , . , , , . , . 8,040,891 1 9 1 5 . . , , , . , , , , . , 6,499,664 1916 . . . . . . . . . . . . 7,346.969
.
.
Lbs. balata 1,517,066 1,318,598 1,533,024 2,472,224
....
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In order to obtain a more correct idea of the importations it is suggested that the figures for these two gums be added and classed together. The present Tariff Act went into effect October 3, 1913, so that it was natural that large quantities of chicle should he imported before that time. The new act pro-
vided for a duty of 1.5 c. per pound on crude chicle and 2 0 c. per pound on refined chicle while balata was admitted free. This no doubt resulted in the importation of some chicle under the name “Balata” and caused the drop in the chicle imports from 1914 to the year 1915. A t this point it is also interesting to note that exports of finished chewing gum to foreign countries have risen from $179,000 in 1914 to $574,400 in 1916. This has been shipped principally to England and Australia. A t a valuation of $o.do per lb. this would represent approximately 718,000 lbs. of chewing gum or x;g,ooo lbs. of dry chicle. The amount of chicle imported, manufactured and consumed in the United States in 1916 was approximately 7,031,000 lbs., equal to over 28,124,000 lbs. of chewing gum. This represents a national consumption of over 844 million packages per annum. THERUBBERTRADELABORATORY 325 ACADEMY STREET NEWARK,NEWJERSEY
REVERSION OF ACID PHOSPHATE B y CARLTONC. JAMES Received March 3, 1917
There seems t o be a n inclination of late among fertilizer a n d S t a t e control chemists t o d o more investigating of phosphates, their properties, a n d their effect upon soils a n d growing crops. Where State laws call for water-soluble phosphoric acid, careful investigation a n d attention is necessary, particularly in order t h a t t h e different brands may not fall below guarantee. A recent article in THISJ O U R N A L b y Mr. E. W. hiagruder’ recalled some work which was done by t h e writer in 1910, upon t h e reversion of acid phosphate by lime, a matter which has claimed t h e attention of chemists in t h e Southeastern states for t h e last two or three years. After having his attention called t o a fertilizer from San Francisco, which h a d evidently undergone reversion during transit t o t h e Hawaiian Islands, t h e writer undertook several experiments with different materials t o find t h e effect these had upon t h e acid phosphate of lime. T o 4 7 5 g. of acid phosphate in three separate bottles were added 2 5 g. lime (CaO), 2 5 g. unground coral sand a n d 2 5 e. unground brown guano, respectively; t h a t is, in each experiment there was added 5 per cent of t h e reverting agent t o t h e superphosphate, which we may consider a maximum amount t o use in practice. It should be explained t h a t t h e unground coral sand is carbonate of lime of 95 t o 98 per cent purity, a n d coarsely granular. T h e brown guano is a low-grade sandy phosphate from Laysan Island, formed b y t h e action of bird droppings upon coral sand with which it is intimately mixed. These mixtures were allowed t o stand 2 0 days, analyses being made of t h e water-soluble phosphoric acid from time t o time as other work permitted. T h e following table shows t h e water-soluble phosphoric acid found i n t h e mixtures at intervals after mixing. 1
THISJOURNAL, 9 (1917). 155.
TABLEI-PER
Vol. 9 , No. 7
WATER-SOLUBLE PHOSPHORIC ACID I N MIXTURES OF ACID PHOSPHATE WITH . . . . . . . .Lime (CaO) Coral Sand Brown Guano
CENT
... . . . . .. . .... . . .
5 Per c e n t . . On mixing., . . , , . . . . . . . . . After 2 d a y s . . . , , . . . . . . . . . . After 5 d a y s . . . . . , . . . . . . , , Aiter 12 d a y s . . ..... . . . . , . After 20 d a y s . . , , . , . . . . . .
21.37 20.83 20.18 19.69 19.12
21.37 21.08 20.75 20.59 20.51
21.37 21.24 21.16 21.00 21.00
This table shows t h a t superphosphate in which there is j per cent coral sand reverts 0 . 6 2 per cent in 5 days or 0 . 8 6 per cent in 2 0 days. With brown guano t h e reversion is not as great, while with lime it is 3 . 75 times as much. If then in a fertilizer guaranteed t o contain I O per cent of phosphoric acid water-soluble, we should have jo per cent acid phosphate of lime a n d 5 per cent calcium carbonate (coral sand), we should expect t o find after j days t h a t instead of I O per cent water-soluble phosphoric acid i t would contain only 1o-(o.62 X 0 .jo) = 9 . 6 9 per cent, t h e difference being caused by coral sand alone. I n order t h a t this fertilizer might show a I O per cent water-soluble phosphoric acid content after 5 days, 5 1 . 5 per cent acid phosphate would have t o be used originally. This example gives t h e effect of b u t one reverting agent, b u t i t is sufficient t o show t h a t quite a material allowance has t o be made in certain fertilizers t o cover reversion during transit. THE PACIFICGUANOAND FERTILIZER COMPANY HONOLULU, HAWAII
A RAPID METHOD FOR THE DETERMINATION OF WATER-SOLUBLE ARSENIC 1N LEAD ARSENATE B y H. A. SCHOLZ AND P. J. WALDSTEIN Received March 5, 1917
The method for t h e determination of water-soluble arsenic in commercial lead arsenate described b y Gray a n d Christie’ is very similar t o t h e method used by t h e writers for factory control during t h e past three years. T h e procedure follows: Weigh 0 . 5 g. of t h e dried and pulverized sample, or I g. of paste, into a 250-cc. volumetric flask. Add 2 0 0 cc. of recently boiled, distilled water and boil vigorously for 3 t o 5 min. Allow t o stand I O or ~j min., cool, make t o volume a n d filter through a dry paper. Ordinary, quickfiltering qualitative paper is‘used and there is rarely any difficulty in obtaining a clear filtrate. Measure zoo cc. into a 500-cc. Erlenmeyer flask, add a few crystals of potassium iodide a n d 7 cc. concentrated sulfuric acid, a n d boil down t o about 50 cc. Dilute with cold water, make alkaline t o methyl orange with sodium hydroxide, acidify with dilute sulfuric acid, and add a n excess of sodium bicarbonate. Titrate with N/20 iodine solution. This method was checked many times on lead arsenates of different compositions against t h e A. 0. A. C. method2 (24 hrs. digestion a t 32’ C.), a n d a few times against t h e Io-day method.3 T h e results always either agreed or came higher by t h e boiling method. Table I gives a few typical results. The arsenates of lead used included t h e products of several other manufacturers a n d represent practically every known commercial method of manufacture. 1 2 8
THISJOURNAL, 8 (1916), 1109. J . of A . 0. A . C.,1918, Nos. 1 and 2. Bureau of Chemistry, Bull. 107, Revised, p. 240.
