574 



SCIENCE 



[N. S. Vol. L. No. 1303 



obtained in the presence of leather. Leather, wood, 

 jute and cork are considered. These are broken 

 down by cresol at 185° C. For tliis reason it is 

 suggested that rubber be digested in cresol for 16 

 hours at 120° C. when the presence of these is 

 suspected. At this temperature the basic sub- 

 stance of these materials is retained intact. 

 Acetylation gives: 



95 per cent, of the wood, 

 90 per cent, of the jute, 

 70 per cent, of the leather, 

 21 per cent, of the cork. 



An approximation of the amount of cork present is 

 obtained by treating the residue after acetylation 

 with 2 per cent, solution of sodium hydroxide and 

 strong bromine water, in order to remove the un- 

 acetylated cork. The loss in weight represents 70 

 per cent, of the total amount of cork present. It 

 was found impossible to determine each of these 

 ingredients separately, and therefore it was de- 

 cided to determine them collectively by the acety- 

 lation method, and to test for the presence of each 

 by means of proper stains and microscopic ex- 

 amination. 



The variability of crude rubier: John B. 

 Tdttle. 



Symposium on the action of accelerators during 

 vulcanization: J. H. ScOTT. 



The action of certain organic accelerators in 

 the vulcanization of rubber: G. D. Keatz, A. H. 

 Flower and Cole Coolidge. The activity of the 

 following substances in accelerating the vulcaniza- 

 tion of a mixture of 92J parts rubber and li parts 

 sulfur was investigated: aniline, urea, thio-urea, 

 mono- and di-phenyl-thio-urea, mono-, di- and tri- 

 phenyl-guanidine, the formaldehyde condensation 

 products of aniline and p-phenylene-diamine, and 

 other substances, including those which produce 

 negative acceleration. Comparisons were made on 

 the above mixture; sulfur coefficients are given. 

 Certain substances were found to decompose into 

 simpler substances containing an active nitrogen 

 group which is responsible for the acceleration 

 effected. Molecularly equivalent quantities of sub- 

 stances which contain the same active nitrogen 

 group in their primary nucleus produced the same 

 accelerating activity. Certain nitrogen groups 

 probably function as sulfur carriers with a tem- 

 porary change from three to five in the valency of 

 the nitrogen. 



Beactions of accelerators during vulcanization: 

 C. W. Bedford and Winfield Scott. 



The effect of organic accelerators on the vulcani- 

 zation coefficient: A brief discussion of the al- 

 ready published work on the relationship of the 

 mechanical properties of vulcanized rubber to the 

 chemical composition, and a description of experi- 

 ments with certain powerful accelerators which 

 demonstrates that under certain conditions good 

 mechanical properties can be obtained in rubber 

 with a very low degree of chemical combination of 

 sulphur. 



The effect of ccmipounding ingredients on the 

 physical properties of rubber: C. Olin North. 



Some methods of testing the hardness of vul- 

 canized rubier: H. P. Gurnet. 



Symposium on the testing of pigments. Led by 

 Geo. Oenslager. Contributions from M. M. Har- 

 rison and M. M. Kahn. 



The manufacture and use of crimson antimony: 



J. M. BlERER. 



Laboratory aprons: C. P. Fox. 



Tlie value of a library to the rubber laboratory : 

 H. E. Simmons. 



Sesearch on sine products for the rubber indus- 

 try : P. R. Croll and I. E. Eubt. 



DYE SECTION 



Charles L. Keese, Chairman . 

 K. Norris Shreve, Secretary 



Introductory remarTcs: Charles L. Eeese. 



Present condition of German dyestuff plants: 

 T. W. Sill. 



Review of the dye situation: J. Meeritt Mat- 

 thews. 



The progress of the American dye industry as 

 shoxon by the census of the Tariff Commission: 

 Grinnell Jones. 



Photosensitizing Dyes: E. Q. Adams. 



The color laboratory of the Bureau of Chemis- 

 try: H. D. GiBBS. 



Alkali fusions: H. D. Gibbs and Max Phillips. 



The system: napthalene-phthalic anhydride: K. 

 P. Monroe. 



The melting point of pure phthalic-anhydride. 

 The system: phthalic anhydride-phthalic acid: K. 

 P. Monroe. 



Benzene sulphonic acids. (I.), benzene disulfonic 

 acid from benzene mono sulfonic add: C. E. Sen- 

 seman. 



Notes on testing dyed goods: W. P. Edwards. 

 During the war period established prejudice made 



