T H E JOL’RNAL 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 is a most e f f e c t u a l retardant, w h e n e m p l o y e d in t h e abs e n c e of z i n c o x i d e . When these two substances were both present in t h e mixture, however, t h e sulfur coefficient obtained was practically t h a t of its control. W i t h p-toluidine, t h e same excess coefficient was obtained in t h e presence a n d absence of zinc oxide, a characteristic similar t o t h a t noted i n t h e case of aniline, a n d t o be discussed in a subsequent paper. I n fact, p-toluidine hydrochloride did not greatly retard t h e vulcanization even when employed i n a rubber-sulfur mixture, a fact which we a t t r i b u t e t o t h e strong basic nature of t h e @-toluidine. When used i n t h e presence of zinc oxide, @-toluidinehydrochloride markedly accelerated t h e vulcanization. T h e physical t e s t results confirmed t h e sulfur coefficients. Entirely different results were obtained, however, with methylaniline hydrochloride.’ This substance, although almost inactive i n a mixture which contained zinc oxide, acted as a r e t a r d a n t i n a mixture of rubber a n d sulfur only. I n this instance, owing t o t h e weakly basic n a t u r e of t h e methylaniline, t h e effect of t h e hydrochloric acid predominated. Here, again, t h e physical properties of t h e mixtures were roughly i n accord with their sulfur coefficients. T h e results show t h a t t h e tendency of certain substances t o decompose or dissociate into other substances with acid properties, or with acid properties predominating, m a y cause t h e substance originally added t o be classed a s inactive or as a retardant. I n such cases, t h e primary function of zinc oxide is t o neutralize t h e acidic constituents a n d permit t h e predominance of t h e accelerator, which is very probably basic. EXPT. m--Many years ago, Gerard2 noted t h a t vulcanization could be effected by boiling rubber i n a concentrated aqueous solution of “liver of sulfur,” a reaction which m a y possibly be represented i n t h e following manner:
’
* KzS04 + 3KzS3 f 4coz + H20 +zKOH + HzS 3. S
4KzC03 f Si0 KzS3
T h e second reaction, which represents t h a t found by Gerard capable of effecting vulcanization, is analogous t o t h e decomposition of ammonium polysulfide :
+
Z“3 f HzS Sx - 1 (NHJzSx I n neither of t h e above instances is t h e possibility of t h e formation of t h e hydrosulfide ( K S H or NHdSH) excluded, b u t i t is regarded as an intermediate reaction. I n t h e present case, where t h e a m m o n i u m sulfides3 were used, t h e resultant system can hardly be acid, no m a t t e r how t h e decomposition or dissociation of t h e sulfide is effected. 1 When heated t o 3.50’ C., methylaniline hydrochloride dissociates into aniline and methyl halide, with the formation of tHe isomeric $-toluidine. Methylaniline hydrochloride was chosen for comparison with $-toluidine hydrochloride, in order t o observe if such a rearrangement took place during the vulcanization reaction. From the sulfur coefficients obtained, i t is obvious t h a t this transformation did not occur. 2 LOC. cit. T h e first use of alkaline sulfides, and particularly potassium pentasulfide, for vulcanization, is often attributed t o Gerard (compare Charles Hancock, Brit. Patent 11,874 (1847), and Moulton. Brit. Patent 13,721 (1851)) 8 Compare the process of Moureley of .Manchester, England, 1884.
Vol. 13, No,
I
A small sample of t h e rubber was sheeted t h i n o n t h e mill a n d cut into two j-g. portions. E a c h portion. was placed i n a glass b o m b tube, a n d a concentrated aqueous solution of ammonium polysulfide was a d d e d t o one, a n d ammonium hydrosulfide t o t h e other. E a c h solution contained approximately 0.5 g. of sulfide sulfur. T h e tubes were sealed a n d heated for 6 hrs. i n a n oil b a t h of 147’ C. B o t h samples appeared t o be vulcanized t o a slight extent. T h e sample heated with ammonium polysulfide was dark i n color a n d quite sticky. T h e o t h e r was lighter in color a n d not so sticky. Both samples were extracted with acetone for 24 hrs., dried, a n d t h e combined sulfur estimated. T h e samples heated with a m m o n i u m polysulfide a n d ammonium hydrosulfide were found t o h a v e sulfur coefficients of I . 933 a n d 4.366, respectively. CONCLUSIONS
I-The activity of synthetic nitrogenous organic substances as accelerators is n o t proportional t o t h e dissociation constants of t h e original substances and, with t h e exception of members of a closely related series, no definite relationship exists between t h e activities and t h e dissociation constants of t h e original substances. 2-Substances which decompose or dissociate i n t o other substances of acid character, or r e a c t with o t h e r components of t h e mixture t o form substances of acid character, do n o t accelerate unless a neutralizing base or salt is present. 3-Vulcanization is effected b y heating rubber i n a closed system with concentrated aqueous solution o f a m m o n i u m sulfides. ELECTRIC OVEN FOR RAPID MOISTURE TESTS1,Z By Guilford L. Spencer TEE CUBAN-AMERICAN SUGAR co., N E W YOKKA N D CUBA
T h e appreciation of t h e role of t h e moisture of r a w sugars in determining their storage qualities, a n d t h e need of very p r o m p t results of moisture tests in sugarcane bagasse, in controlling t h e mill work, led t h e a u t h o r t o devise a n oven for rapid tests. T h e ordinary types of ovens are of great value in these tests, b u t unfortunately t h e results in their use cannot be reported with sufficient promptness t o meet t h e needs of thorough factory control. If r a w sugar contains more moisture t h a n a certain safety factor indicates is desirable, i t m a y break down before i t reaches t h e market or refiner and serious loss of sucrose result. If t h e residue of cane milling, t h e bagasse, contains excessive moisture, this necessitates a waste of fuel a n d a loss of sugar. T h e oven here described is t h e result of several years’ experimenting and t h e construction of several models. As indicative of t h e rapidity t h a t has been achieved i n t h e present model, r a w sugar m a y be dried i n i t in I O min., a n d cane bagasse i n about 3 0 min. It was hoped t o present comparative tests of several’ materials a n d more systematic experiments with sugars, U. S. Patent 1,348,757. Presented before the Section of Sugar Chemistry a t the 60th Meeting of the American Chemical Society, Chicago, Ill., September 6 t o 10, 1920. 1 2
Jan.,
1921
T H E JOURNAL OF INDUSTRIAL A N D ENGINEERING CHEMISTRY
but t h e pressure of manufacturing duties prevented t h e laboratories from doing more extended experimenting. D E S C K I P T I O S O F OVEN
Briefly, t h e oven is a convenient device for conveying a large volume of heated air through a capsule containing t h e material t o be dried. T h e current of air is induced by a steam ejector or a n air p u m p . Connection is made with t h e vacuum system i n sugar factories. T h e heated air is carried against t h e cover of t h e oven t o promote mixing. T h e drying capsule m a y be of metal or other construction, b u t , for sugar work and a large proportion of general tests, metal is most suitable. T h e bottom of t h e capsule is closed with monel metal filter cloth, which freely passes air b u t retains very fine powders. T h e capsule makes a joint with its seat in t h e oven, over a n annular channel which connects several capsule openings, and leads t o t h e vacuum p u m p or ejector connection. T h e air inlet t o t h e oven m a y be regulated, if desired, for operating under a partial vacuum. T h e air is drawn over a heating element consisting of spiraled resistance wire wound over a core. T h e travel of t h e air is directed through a very narrow annular space, occupied b y t h e resistance wire, which forces i t into intimate contact with t h e resistor. T h e element is housed inside t h e oven's drying chamber, t h u s reducing radiation loss. T h e air pressure o n t h e material in t h e capsule forces t h e latter t o a good seat and prevents air leakage. T h e oven is made in two sizes, small for general use and large for bulky materials. T h e service wires are connected in series with a sliding contact rheostat for temperature control, a n electric time switch or interval timer, and t h e heating element. T h e time switch opens t h e circuit a n d rings a bell at t h e termination of t h e drying period. T h e heating element is housed conveniently for renewal.
placed in a capsule in t h e cold oven and heated a t I0j0
c.
Dry weight of cotton. ................................ 0.8888 Weight after 5 min. drying.. ......................... 0.9858 Weight after an additional 5 min. drying.. . . . . . . . . . . . . . 0.8889 COMPARATIVE TESTS W I T H OLD T Y P E OVEN
A t intervals, this company distributes control samples among its laboratories, through i t s central control, laboratory. These samples are tested independently by t h e chemists conducting t h e routine factory control, and t h e results are reported t o t h e author's office for tabulation and comparison. 'The figures quoted below are from such tests. A number of individual tests are given t o call attention t o variations. I n t h e tests of raw sugar (Series I), t h e drying period was 2 0 min. a t 105' C. with t h e new t y p e of oven, starting with t h e oven cold. I n t h e usual types of electric oven, t h e drying period was t h e customary 3 . j hrs. a t 1 0 j O C. SERIESI
New Oven
Chemist., . . . . . . . . . . . . . A B Per cent moisture.. . . . . 0.72 0.73 Average per cent moisture = 0.74
C
D1
E'
F
0.72
0.78
0.78
0 70
Usual T y p e Electric Oven J K Control Laboratory 0.72 0.75 0.76 0.79 0.77
Chemist . . . . . . . . . . G H I Per cent moisture.. 0.68 0.74 0.69 Average of factory laboratories 0.72 Average of control laboratory = 0.77 Average of all tests = 0.74 1 Effluent air temperature, 95' C.
-
A second sample was sent t o t h e various factory laboratories, in which every precaution was observed t o assure thorough mixing of t h e sugar, and complete filling and proper sealing of t h e bottles. A sugar of very high moisture test was purposely selected. Four heating periods were specified for t h e new oven, a capsule of sugar for each, and t h e customary period of 3.5 hrs. for t h e ordinary oven. T h e temperature in each test was I O j o C. T h e results are tabulated in Series 11: SERIESI1 Arezo~ &en
O P E R A T I O N OF O V E N
T h e time switch is adjusted for t h e desired drying period; t h e capsule, with t h e sample, is placed on its seat in t h e oven and t h e unused openings are closed; t h e vacuum or p u m p connection is opened; t h e time switch is closed and t h e clock is s t a r t e d ; t h e resistance is rapidly cut out with t h e rheostat slide, and t h e temperature is regulated. T h e drying now proceeds until t h e time switch opens t h e circuit a n d rings a bell, signaling t h e termination of t h e operation. -1ny material t h a t will freely pass a current of air m a y be dried in this oven. Refinery press-cake, consisting almost entirely of kieselguhr ("filter-cel") is successfully dried. Liquids must be absorbed by a suitable carrier and this be placed in a capsule. T h e thermometer bulb must be located immediately over t h e capsule. Owing t o t h e short drying period, i t has not been found necessary t o use a thermostat, though provision is made for one. About one minute is required t o heat t h e oven t o t h e drying temperature. T h e following experiment with absorbent cotton indicates t h e r a t e of drying t h a t may be attained: a sample of cotton was dried t o constant weight, t h e n s a t u r a t e d with distilled water, and in this condition
71
Chemist ,-----A----Drying period min. 3 Per cent moist'ure.. 1.36 Chemist P Drying period, min. 3 Per cent moisture.. 1.28 Average = 1.45 (20 m i n )
---A 5 15 1.40 1.45
B 5 15 1.33 1.39
20
1.47
.
20 1.42
3 1.35
(retests)-----
5 15 1.40 1.45
20 1.47
r -DL--------. -
3 1.38
Usual T y p e Electric O w n Chemist H I L M N Per cent moisture.. 1.52 1.43 1.52 1.43 1 .SO Average of 17 factory tests = 1.48 1 Effluent air temperature, 95' C.
5 1.42
15 1.44
20
1.44
Control Chemists Av., 1.50
T h e tests b y Chemists D and E were made in an early model of t h e oven i n which t h e heating element is immediately over t h e capsule. For this reason t h e temperature of t h e air after passing through t h e capsule is given. There is always danger of overheating with this arrangement a n d i t has been abandoned. Most of these tests, except in t h e central control laboratory, were made by young men with very little laboratory experience. This applies t o both ovens, so these conditions were alike. Apparently t h e conditions t h a t lead t o irregularities are no more in evidence in t h e new t h a n i n t h e usual ovens. There is probably less danger of decomposition of t h e material during desiccation in t h e new t h a n in other ovens.
72
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
b y reason of t h e very short heating period a n d t h e p r o m p t removal of t h e vapors. Cane bagasse apparently withstands high temperatures and is usually dried in t h e ordinary ovens at 110' t o 115' C. It m a y be dried in the new oven at 130' or even 140' C. without decomposition t h a t introduces an appreciable error. A sample weighing I O O
Vol. 13, No.
I
g. a n d containing j o per cent moisture m a y be dried in t h e large oven at 130' C. i n 3 0 min., t h e drying period depending somewhat upon t h e mechanical s t a t e of t h e material. Samples h a v e been dried at t h e high temperature, during various periods ranging from 30 min. t o 90 min., without increase in t h e indicated moisture.
ADDRESSES AND CONTRIBUTED ARTICLES THE CHEMISTRY OF VITAMINES' By Atherton Seidell HYGIENIC LABORATORY, U. S . PUBLIC HEALTH SERVICE, WASHINGTON. D. C
The first indication of the existence of the substances now designated by the term vitamine was obtained some twelve years ago during the investigation of the cause of beri beri, a disease prevalent among people who consume rice as their chief article of diet. This disease originated after the introduction of modern milling methods in which the surface layers of the rice are removed by a polishing process. It was found that the disease could be prevented by adding to the diet rice polishings or extracts of these. In 191I Casimir Funk, who was engaged in attempts to isolate, by chemical means, the constituent of rice polishings responsible for the remarkable curative effects, proposed that this hitherto unrecognized substance be called vitamine. He also developed the conception of deficiency diseases and collected much evidence to prove that the absence of these previously unrecognized substances from an otherwise adequate diet is the cause of serious nutritional disturbances, resulting in characteristic abnormal conditions. Among such diseases he included beri beri, polyneuritis in pigeons, scurvy, and pellagra. The term vitamine, therefore, refers t o one or more substances of unknown composition, extremely small amounts of which are necessary for normal nutrition. Although many attempts have been made to isolate vitamine, none have so far been successful, and our knowledge of this class of substances is, therefore, still limited almost entirely to the physiological effects they produce. Since it has not been possible to determine the vitamine content of foods by chemical methods, feeding experiments for this purpose have been developed and extensively applied. The principle on which these are based is the feeding of diets which contain adequate amounts of the hitherto recognized essential dietary constituents, namely, carbohydrates, protein, fats, and inorganic salts, highly purified to insure that they contain no vitamine, and simultaneously giving measured amounts of the sample being tested for its vitamine content. On the basis of such experiments tables have been constructed which show the comparative amount of vitamine in a large number of foodstuffs. Furthermore, this work has led to the differentiation of a t least three well-characterized vitamines. These are the water-soluble antineuritic vitamine, the fat-soluble, growthpromoting vitamine, and the antiscorbutic vitamine. Of these, the first appears to be the most stable towards the chemical manipulations required for its separation from the substances with which it occurs naturally. It is this one, therefore, which has received most attention a t the hands of chemists. Although the results which have been obtained so far have not greatly clarified the problem as to the chemical nature of this unknown essential dietary constituent, it is believed that a brief review of the experiments along this line may prove of general interest. 1 Address of the retiring president of the ChernicalSociety of Washington, November 11, 1920.
EXPERIMENTAL PROCEDURES
A t the time Funk began work on the problem the following
facts had been qualitatively established in regard to the antineuritic vitamine. It is neither a salt nor a protein. It is soluble in water and in alcohol. It is dialyzable. and is destroyed by heating t o 130' C. Funk and others have since shown that it is not destroyed by hydrolysis for 24 hrs. with 2 0 per cent sulfuric acid. It has also been found that phosphotungstic acid precipitates this vitamine completely from aqueous solution. Funk's method for its isolation is, accordingly, based upon the use of this reagent. I n general, the procedure consists in extracting the raw material with acidified alcohol, evaporating the extract to a small volume, acidifying the aqueous solution with about I O per cent of sulfuric acid, and precipitating with phosphotungstic acid. This precipitate is decomposed with excess of barium hydroxide, and after removal of the excess of the latter, the solution is acidified with hydrochloric acid and evaporated. The residue is extracted with alcohol and the alcoholic solution further purified by precipitating with various reagents, such as lead acetate, mercuric chloride, silver nitrate alone and followed by barium hydroxide, phosphotungstic acid, silicotungstic acid, etc. Funk at first ,reported that the crystalline material he succeeded in isolating from rice polishings, yeast, milk, bran, and other materials, by means OIphosphotungstic acid precipitation and subsequent decomposition of this precipitate, was the antineuritic vitamine. Later, in collaboration with Drummond, he was forced to abandon this position since the compound he originally thought was vitamine proved to be nearly pure nicotinic acid. Retraction was therefore made of the claim that isolation of the curative substance had been effected. A number of other investigators have followed this general procedure and have reported the isolation of crystalline compounds with antineuritic properties. Thus, Suzuki, Shimamora, and Odake have given the name oryzanin to an active product they obtained from rice polishings by alcoholic extraction followed by phosphotungstic acid precipitation. Their experiments were repeated by Drummond and Funk but their results were not confirmed. Edie and his co-workers isolated a crystalline product from yeast by methyl alcohol extraction and silver nitrate-baryta precipitation to which they gave the name torulin, but for which further evidence is lacking that it is pure vitamine. Numerous modifications of the general plan of extracting and precipitating have been tried without success and many novel procedures have been introduced. Thus, Sugiura recently made use of air dialysis to obtain crystalline vitamine from water extracts of dried yeast. The yield was very minute and physiological tests of the product did not indicate that it possessed an exceptionally high degree of activity. McCollum reported that although organic solvents, such as ether, benzene, and acetone, do not extract the antineuritic vitamine directly, if the alcohol extract of the vitamine-containing material is evaporated on dextrin, and this extracted with the organic solvent, benzene appears to dissolve the vitamine, but acetone does soTtozonly a very slight extent.
