Januaey 20, 1922] 



SCIENCE 



79 



meat. Hence, by the determination of the O. P. 

 of an unknown pigment it is possible to predict 

 what its practical compounding value will be in 

 relation to known pigments. 



The solubility of sulfur in rubber: C. S. 

 Venable and C. D. Green. Values have been 

 obtained for the solubility of sulfur in rubber 

 at 55°, 75°, 95° C. The procedure used was 

 essentially to pack thin rubber strips in sulfur, 

 maintain at the desired temperature until equi- 

 librium was reached, and then analyze for com- 

 bined and free sulfur. Various precautions were 

 adopted to insure that equilibrium was reached. 

 It was found that the solubility of sulfur in 

 rubber increases slowly with the vulcanization 

 coefficient, this increase being more rapid as the 

 temperature increases. It was found that when 

 this coefficient was greater than 7 per cent, com- 

 bined sulfur, it was impossible to obtain solu- 

 bility values by the method used due to the fact 

 that the rubber becomes almost impermeable to 

 free sulfur. This impermeability probably has 

 more to do with the non-blooming of hard rubber 

 stocks than the increased solubility of free 

 sulfur. By extrapolating the curves obtained, it 

 can be calculated that a stock having 4 per cent, 

 combined sulfur at 140° C will be saturated with 

 about 15 per cent, free sulfur. 



Beactions of accelerators during vulcanisation. 

 IV. Mechanism of the action of zinc compounds: 

 C. W. Bedford and L. B. Sebkell. Zinc sulphy- 

 drate vulcanizes rubber in the presence of sulfur 

 at ordinary temperatures. Zinc persulfides are 

 stable compounds and vulcanize rubber in heat 

 cures far more rapidly than ordinary sulfur. 

 Zinc salts of organic accelerators form polysul- 

 fldes without decomposition into zinc sulfide and 

 disulfides. Disulfides are changed to mercaptans 

 by hydrogen sulfide and in the presence of zinc 

 oxide they form zinc salts. (An answer to Bruni, 

 India Subber J., 62 [1921] 63.) 



The action of volatile organic solvents and 

 vulcanizing agents on organic compounding mate- 

 rials and resinous gums: Frederick Dannerth. 

 The purpose of this investigation has been to 

 obtain fundamental data for the industries which 

 use plastic masses. The amount of matter soluble 

 in certain liquids at stated temperatures has been 

 studied. We have also noted: The amount of a 

 given solvent which will mix with any other 

 given solvent at a given temperature; the swelling 

 action of certain solvents on stated organic mate- 

 rials; the action of certain vulcanizing agents 

 on pitches and oils as well as their action on 



chicle, balata, guttapercha and jelutong. The 

 influence of the product has been studied, first 

 using only organic compounding material and 

 secondly using only the resinous gums. 



The preparation and testing of crude rubber: 

 O. DE Vries. 



Section of Cellulose Chemistry 

 Harold Hibbert, chairman. 

 G. J. Esselen, Jr., secretary. 



Acetolysis of spruce pulp. Preliminary com- 

 munication: "Walter Btjssell and Louis E. 

 Wise. Acetolysis of spruce sulfite pulp, when 

 carried out as in the case of acetolysis of cotton, 

 yields appreciable amounts of cellobiose octa- 

 aeetate. The yield of cellobiose appears to de- 

 pend on the normal (Alpha) cellulose content of 

 the pulp, rather than on the so-called ' ' total 

 cellulose. ' ' The cellobiose reaction furnishes an- 

 other link in the chain of evidence that the 

 normal cellulose of spruce wood is chemically 

 similar, if not identical with that of cotton. 



Studies on cellulose chemistry. III. The con- 

 stitution of cellulose: Harold Hibbert. The 

 recent work of Karrer and of Freudenberg on 

 octacetylcellobiose confirms the view advanced 

 previously by the writer that the ratio of this 

 product to dextrose pentacetate obtained from 

 the decomposition of cellulose acetate is much 

 higher than corresponds to the pentaglucosidyl- 

 glucose formula for cellulose put forward by 

 Hess. The results cast considerable doubt on the 

 correctness of his formula, but, on the other 

 hand, are in no way in disagreement with that 

 advocated by the writer. Further evidence in 

 support of these is to be found in the recent 

 paper of Denliam on the methylation of cellulose. 



IV. The action of SBr on carbohydrates and 

 polysaccharides: Harold Hibbert and Harold 

 S. Hill. Cellobiose gives a yield of 27 per cent, 

 of bromomethylfurfuraldehyde while lactose 

 gives less than 7.0. These two derivatives are 

 structurally identical and there is thus the possi- 

 bility of utilizing this reaction for the deter- 

 mination of contiguration. The mechanism of the 

 reaction is being carefully studied in view of its 

 bearing on the constitution of cellulose. 



The condensation of citral, with certain Tcetones 

 and the synthesis of some new ionones: Harold 

 Hibbert and Laura G. Cannon. The best 

 method for purifying citral is the one developed 

 by Tiemann. Of the condensing agents hitherto 

 employed, sodium ethylate is the most satisfac- 

 tory, but metallic sodium is equally efficient. 

 Better yields of a purer product have been ob- 



