August 26, 1921] 



SCIENCE 



175 



found to reduce the time of cure by seven eighths, 

 and even at 130° to lead to curing in about one 

 third of the time required at 141° in its absence. 

 At the optimum cure rubber containing the base 

 showed (a) a noticeably lower sulfur coefficient, 

 (6) a very considerably higher breaking stress, 

 (c) a noticeably smaller elongation, and (d) a 

 lower position of the stress-strain curve (strains 

 as ordinates) than did rubber from which the 

 base was absent. On aging for 7 months, vulcaiii- 

 zates prepared with the base behaved in a manner 

 essentially similar to that shown by vulcanizates 

 prepared without it; the stress-strain curves com- 

 ing down the paper to a similar extent and the 

 breaking points altering in a similar way. 



A rapid homb method for the determination of 

 sulfur in rubber compounds: W. W. Evans and 

 Rdth E. Merling. 



The direct determination of the sulfur of vul- 

 canization: S. Collier and Michael Levin. The 

 sulphur actually combined with the rubber is de- 

 termined by dissolving the rubber and polyprene 

 sulphide in cymene. The solution is diluted with 

 petroleum ether and filtered after the fillers have 

 settled out. The filtrate containing the poly- 

 prene sulphide is evaporated to dryness by heat- 

 ing on the steam bath and by means of a gentle 

 current of air. The residue is dissolved in nitric 

 acid and the solution evaporated to dryness. 

 Three c.c. of nitric acid are added to the residue 

 and then 5 grams of sodium carbonate. The mix- 

 ture is fused and the amount of sulphur deter- 

 mined. 



Volume increase of compounded rubber under 

 strain. (Lantern.) (With comments on the work 

 of H. F. Schippel.) : Henry Green. 



A general round table discussion followed on 

 the topics of factory control of vulcanization, 

 testing of crude rubber as received at the factory, 

 reactions between sulfur and various softeners, 

 and others. 



DIVISION or BIOLOGICAL CHEMISTRY 



A. W. Dox, chairman. 

 H. B. Lewis, secretary. 



A study of the highly unsaturated fatty adds 

 occurring in fish oils: G. D. Beal and J. B. 

 Brown. A proximate determination of the com- 

 position of five commercial fish oils was made by 

 converting a kilo of each of the oils into its 

 methyl esters by a modified Haller methanolysis, 

 distilling these into ten-degree fractions under 



reduced pressure and analyzing these fractions. 

 Evidence for the presence of myristic, palmitic 

 and clupanodonic acids was given, and also for 

 acids more highly unsaturated and of greater 

 molecular weight than clupanodonic acid. When 

 the refractive indices of the fractions were plotted 

 against the corresponding iodine numbers and 

 mean molecular weights of the acids, curves which 

 were nearly straight lines were produced. The 

 analytical data showed a decided similarity for 

 the oils examined, which included salmon, men- 

 haden, herring, cod and sardine oils. The pure 

 highly unsaturated acids were prepared in more 

 than 50 per cent, yield by reduction of their 

 methyl ester polybromides in methyl alcohol with 

 zinc dust. The mean molecular weight of these 

 acids by titration was over three hundred, a value 

 much too high for clupanodonic acid. Distilla- 

 tion of the methyl esters of these acids and analy- 

 sis of the fractions gave good evidence for the 

 presence of the following acids — hexadecatrienoie, 

 CmHjoO., clupanodonic, CmHjsO;, arachidonio, 

 CkHjoO;, eicosapentenoic, C20H30O,, docosapentenoic, 

 CijHa^O., and docosahexenoic, C^HjoO;. 



Further studies on the mosaic disease of spinach : 

 S. L. JODIDI. Mosaic disease affects many crops 

 of vast economic importance such as the Irish 

 potato, tobacco, corn, sugar beet, sugar cane, 

 spinach, cabbage, lettuce, tomato, cucumber, and 

 others. It seemed quite desirable to study the 

 mosaic disease of at least one crop — in this ease 

 spinach — from various angles and by various 

 methods. The results of the investigation have led 

 to the following conclusions: (1) The physical 

 and chemical properties of the soil taken from 

 under diseased spinach plants were found to ap- 

 proach very closely those of the soil taken from 

 under healthy plants. (2) The differences in the 

 biological behavior of the two soils under con- 

 sideration, as shown by their ability to ammonify 

 various organic nitrogenous compounds, were so 

 small as to be negligible. (3) The mosaic disease 

 of spinach does not seem to be due to malnutrition, 

 since in the experiments reported the diseased con- 

 dition of the plants can not be ascribed to phys- 

 ical, chemical and biological conditions obtaining 

 in the soil. 



Chemical, physical and insecticidal studies of ar- 

 senicals: F. 0. Cook and N. E. McIndoo. 



Cysteine as a product of the intermediary metab- 

 olism of cystine : H. B. Lewis and Lucie E. Root. 

 After the administration either orally or sub- 

 cutaneously of 1-phenyluraminocystine to rabbits, 



