July, 1929
IXDCSTRIAL ALVDENGINEERING CHEMISTRY
hide. These facts would indicate that the organic matter in the syntan solution acts in a manner similar to certain organic non-taris. I n a previous publication from this laboratory- (3) . _it was shown that pyrogallol in low concentrations increases rate of tanning by tannic acid solutions a t pH = 2, while it inhibits the tanning a t high concentrations. This is similar to the action of the syntan reported in this paper. Within the limited scope of the experiments reported a t this time, it may be stated that a syntan increases rate of tanning of a vegetable extract due to its acid reaction, but with the advantage over the mere effect of lowered p H residing in some as yet-unexplainable qualities of the organic
701
matter present, the latter inhibiting "dead tanning" and producing a lighter colored tanned hide powder. Acknowledgment
The authon are pleased to express their appreciation for aid in this investigation received from A, F, Gallun of Milwaukee. Literature Cited (l) Bambergerp C h e m . - Z t g . , '1 318 (1919). (2) Kohn, Breeds, and Crede, J. Am. Leather Chew. Assocn., 11, I73 (1922). (3) Thomas and Kelly, IXD. END. CHEM..11, 41 (1925).
Effect of Pretreatment upon Hydrolysis of Hide Powder b y Saturated Calcium Hydroxide Solutions'" Arthur W. Thomas and Margaret W. Kelly DEPARTMENT OF
CHEhfISl'RY.
COLWlrBI.4 UNIVERSITY.
BSERVATIOSS in this laboratory on the behavior of gelatin have shown that when small blocks of gelatin jelly are thoroughly dried they will subsequently swell when placed in acid or alkaline solutions, provided the blocks have not been stored in the dried state for too long a time. Blocks a year old, or older, disintegrate when placed in acid or alkaline solutions. The strong forces of compression resulting from the attractive forces of the gelatin molecules in the dried bulk seem, therefore, to result in disruptive strains in the course of time. Since hides as received by the tanner may he fresh, wet ("green"), salted, or thoroughly dried, and in view of the gelatin phenomenon mentioned, i t was considered of value to find out whether desiccation or humidification of hide powder has any influence upon the loss of hide substance during subsequent soaking in limewater. Incidentally, since hide powder is preserved better in sodium sulfate than in sodium chloride solutions (@,* hide powder that had been soaked in saturated solutions of these salts was included in this study.
0
Pretreatment
Specimens of hide powder were subjected to the action of atmospheres of varying degrees of humidity until the protein had reached equilibrium with the moisture content of the atmosphere. Fifteen-gram portions of American standard hide powder were placed in dishes in the upper compartments of desiccators. The desired humidity was obtained by means of sulfuric acid solutions in the bottom of each desiccator. A small portion of hide powder in an open weighing bottle was also placed alongside of the 15-gram portion in order t o determine attainment of equilibrium as revealed by constancy of weight of the small sample. The pretreatments were carried out a t 0 and 50 per cent humidity I Presented before the Division of Leather and Gelatin Chemistry a t the 74th Meeting of the American Chemical Society, Detroit, Mich., September 5 to 10, 1927. Received March 6, 1929. 2 Contribution from the Chemical Laboratories, Columbia University.
KO.600.
* Italic numbers in parenthesis refrr t o literature cited a t end of article.
NEW
YORK,
N. Y
a t 37.5" C., and a t 0, 50, and 100 per cent humidity at room temperature and a t approximately 4' C. The hide powder exposed to an atmosphere saturated with water vapor a t room temperature underwent slight bacterid decomposition in 20 weeks, as evidenced by an unpleasant odor. A small amount of mold also appeared. At 37.5" C. and 100 per cent humidity the same sort of decomposition took place so rapidly and to such an extent that the sample was discarded a t the end of 8 weeks. I n each case, together with the foul odor, the weights of the small "pilot" samples showed a sudden decrease, thus further indicating decomposition into volatile products. At 4" C. slight evidence of this sort appeared a t 190 days. For the attainment of moisture equilibrium a t 50 per cent humidity the following time intervals were required-at 37.5" C. 50 days, a t room temperature 60 days, and a t 4" C. 190 days. At 0 per cent humidity the equilibrium times were a t 60 days 37.5" C., 90 days a t room temperature, and 150 days a t 4" C. All were kept under the conditions described, however, for 190 days. In the case of pretreatment with saturated salt solutions, samples of hide powder after 84 weeks' contact a t room temperature with the solutions were filtered off, washed thoroughly t o remove salt and soluble nitrogenous products, squeezed as dry as possible, and analyzed for water and ash content. Treatment with Limewater
After the specified pretreatment the samples of hide powder were transferred to stoppered bottles containing 300 cc. of saturated limewater. I n all cases this volume (300 cc.) was corrected for gain or loss in water content of the original 15-gram sample of hide powder. The limewater digestions were done a t room temperature. At the intervals noted in Table I portions of the liquids were pipetted out, filtered through a dry filter paper, and samples of the clear filtrates analyzed for nitrogen content by the Kjeldahl method. From the nitrogen content of the filtrate and the nitrogen content (2.346 grams) of the original 15-gram sample of hide powder, the per cent of hydrolysis
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I N D U S T R I A L ALVDENGIL\INEERINGCHEIMISTR Y
Vol. 21, No. 7
T a b l e I-Influence of P r e t r e a t m e n t upon Hydrolysis of H i d e Powder in Sat1 t e d L i m e w a t e r PRETREATMENT O F HIDE POWDER Temperature
Humidity
c.
%
Storage for 190 days at: 4 (approx.)
A T R O O M TEMP.
%
6 days
5
10 days
6
%
25 24 20
32 31 27
34 34 30
0
17 10 19
25 20 22
33 28 22
34 26 20
7.7
9.7
17 17
27 28
30 30
3 1 2.0 4 6
6.3 4.2 14
14 8 21
13
0 50
Soaking for 84 weeks a t room temperature in: Saturated NatSOd Saturated NaC1 Distilled H20
P R ET R E ATM E NT
70
3 days
12 11
50 100
37.5
1 day
0 50
100
Room
HYDROLYSIS I N LIXEWATER AFTER:
..
"
.,
was calculated, correction being made in each case for volume of solution previously removed for analysis.
The hydrolysis of the samples previously exposed to solutions of sodium chloride and sodium sulfate shows that the sulfate-treated hide powder decomposes more readily in limewater than that treated with the chloride. There is the possibility that more readily hydrolyzed parts of the hide powder were removed in the saturated sodium chloride solution previous to treatment mith limewater, while the preservative action of the sodium sulfate kept such materials in the hide powder intact until it was exposed to the action of the limewater. It is permissible to speculate on the fact that since sulfate ion is a t the extreme precipitating or dehydrating end of the Hofmeister series, it may provoke a stringent effect similar to that of exposure to zero per cent humidity followed by more ready disruption of the protein in limewater, just as old dried gelatin blocks disintegrate in acid or alkaline solutions. The data given in this paper are a repetition of experiments performed previously (1).
Results
Acknowledgment
Table I and Figures 1 t o 4 show the results obtained. With the exception of the data a t 37.5" C., the results reveal that previous thorough desiccation of hide powder causes perceptibly greater hydrolysis in limewater. The values for per cent hydrolysis are valuable in a relative rather than an absolute sense, owing to the variation in the swelling of the hide powder in the saturated calcium hydroxide solutions, thus rendering the analysis of the outer solution a true aliquot of the total water present only provided the nitrogenous decomposition products are distributed in equal concentration in the free water and in the water held by imbibition in the swollen collagenous network. From unpublished results with the limewater hydrolysis of hide powder that had been previously soaked in saturated calcium chloride solution for 84 weeks, the authors know that this equality of concentration is not always established. I n this instance marked swelling of the hide powder occurred in the limewater, the nitrogen figures on an aliquot of the outer solution showing almost 50 per cent hydrolysis in one day's contact with the limewater, which then abruptly fell to a figure indicating 35 per cent hydrolysis a t the end of 10 days. Concomitantly with this false indication of high degree of hydrolysis followed by a lower value for hydrolysis, there was a very marked swelling of the hide powder residue followed by a deflation of swelling and disintegration. The apparent anomaly of a falling off of the indicated degree of hydrolysis is thus explained. The results in Figure 1 have relative value for the purpose of showing that desiccation renders hide substance more susceptible to hydrolysis in limewater.
The authors are indebted to A. F. Gallun &- Sons Corporation, of Milwaukee, for aid in this investigation.
Y
0
5
lo 0
5
l0
T i m e in Days
Literature Cited (1) Kelly, paper presented before the Division of Leather and Gelatin Chemistry a t the 72nd Meeting of the American Chemical Society, Philadelphia, P a . , September 5 t o 11, 1926. (2) Thomas and Foster, IND. ENG. CHEM.,17, 1162 (1925).
Terms of Proposed Dead Sea Salts Concession The Secretary of State for the Colonies has issued the terms of the proposed agreement and draft concession for the development of the salt deposits in the Dead Sea. Under the proposed agreement the applicants will be required within twelve months of the date of signature to form a company, either in Great Britain or Palestine, with a nominal capital of not less than ElOO,OOO, the prospectus and organization of this company to be under the supervision of the crown agents for the Colonies and the governments of Palestine and Transjordania. Not less than one-half of any capital or debentures in excess of 2250,000 shall be offered for public subscription, and Palestinian citizens and Transjordanian nationals shall have a prior right to the allotment of not less than one-fifth of such public issue. The principal provisions of the proposed concession include the following: The concession shall be for a period of 75 years with an exclusive concession for the first 25 years. The company will be required to produce a minimum of 1000 tons of potassium chloride of 80 per cent purity, or its equivalent, during the third year, rising to 50,000 tons per year after the tenth year. Five per cent of the value in bulk a t the works of the potassium chloride, bromine, and magnesium chloride produced will be payable as royalty. The governments of Palestine and Transjordania will share in the profits of the company on an agreed sliding scale.
