June 24, 1921] 



SCIENCE 



581 



homologs of ibenzene and in halogenated deriva- 

 tives of ibenzene and its homologs. The silver 

 salts form gels at a lower point in the series of 

 saturated fatty acids than do the albali-metal 

 salts; gels being obtained with silver caproate. 

 A number of regularities were discernible. The 

 sUver salts of the higher members of the saturated 

 fatty acid series show a greater solvation capacity 

 than those of the lower ones. None of the satu- 

 rated fatty acid sOver salts gave a gel in benzene ; 

 but silver oleate did. Speaking generally, in the 

 case of solvents of the same general chemical char- 

 acter, the higher the boUing point of the solvent, 

 the greater appeared to be the solvation capacity 

 of a given salt, and the smaller the extent to which 

 the gel from a given salt suffered syneresis. 



Catalytic effect in the reaction between Icetones 

 and halogens in aqueons solutions: P. O. EiCE. 

 The velocity constant of the reaction between ace- 

 tone and bromine is independent of the bromine 

 concentration and Lapworth {J. C. S. Trans., 1904, 

 p. 30) explained this iby saying that the acetone 

 slowly enolized and the addition of bromine and 

 splitting off of hydrobromic acid were practically 

 instantaneous. This is probably incorrect since 

 higher ketones have the same velocity constant as 

 acetone, and an explanation based on the radia- 

 tion theory was offered. The reaction is acceler- 

 ated by neutral salts contrary to Lapworth 's state- 

 ment. 



The transference numbers of sulfuric acid by the 

 concentration cell method: A. L. Pergusox and 

 W. G. France. A cell combination was used which 

 permitted the measurement of all the required po- 

 tentials from one set-up. The value obtained for 

 the transference number for the anion in concen- 

 trations between M/IQ and M/lOO at 25° C. was 

 .1868 ± .0007. The method was shown to be 

 highly reliaible. In all of the calculations it was 

 assumed that sulfuric acid dissociates into two 

 hydrogen and one sulfate ion. This assumption 

 was substantiated by the results obtained. A 

 formula for iboundary potential was developed in 

 which boundary potential may be obtained from 

 potential measurements alone. 



The influence of gelatin on the transference num- 

 bers of sulfuric acid: Alfred L. Ferguson and 

 W. G. France. The transference numbers were 

 determined by the concentration cell method. So- 

 lutions of sulfuric acid containing from 0.5 per 

 cent, to 20 per cent, gelatin were used. The trans- 

 ference numbers of the anion increased from .187 

 for pure acid to .685 for acid containing 20 per 



cent, gelatin. In the 20 per cent, gelatin solu- 

 tion the boundary potential of both concentration 

 cells became zero. The decrease in conductivity 

 was approximately proportional to the gelatin 

 added. The results are probably best explained 

 on the assumption that there is a chemical action 

 (between the gelatin and sulfuric acid in which a 

 single compound is formed. In this compound the 

 hydrogen of the acid loses its identity and when 

 the compound dissociates there is formed a com- 

 plex gelatin hydrogen positive ion and a negative 

 sulfate ion. 



The entropy of monatomio gases: Gilbert N. 

 Lewis. 



The electrometric titration of uranium with 

 potassium diohromate and potassium permanga- 

 nate: D. T. EwiNG and E. F. Eldridge. 



The heat of coagulation of ferric oxide hydrosol 

 by electrolytes: Frederick L. Brown and J. H. 

 Mathews. 



Some quantitative experiments on coagulation of 

 colloids: Eat V. Murphy and J. H. Mathews. 

 The lowest concentration (limiting concentration) 

 of electrolytes necessary to coagulate hydrous 

 ferric oxide sol has been studied as a function of 

 the purity of the sol (ratio of gram-equivalents 

 of Fe to gram-equivalents of CI) and of the 

 concentration of Fe^Os. Chloride, chromate and 

 ferricyanide ions were used in the form of the 

 potassium salts. The conclusions dravra are: (1) 

 The limiting concentration decreases with increas- 

 ing purity in the case of all three ions, the mech- 

 anism of the process being evidently similar for 

 the three ions; (2) The limiting concentration 

 decreases markedly with decreasing concentration 

 of the sol in the case of all three ions, but the 

 relation indicated by Burton and Bishop, Jour. 

 Phys. Chem., 24, 701 (1920), for mastic, A.sSa 

 and Cu sols, holds for Fe^Oa hydrosol only in the 

 case of the trivaleut ion. 



The alkalinity of Searles Lake brine: Roger C. 

 Wells. The title may mean either the titration 

 alkalinity or the hydrogen ion concentrations. The 

 latter may be considered as determined by certain 

 proportions of the four buffer substances Na-COs, 

 NaHCOa, Na3407, and Na^BA- The writer has 

 found for the brine Pjj = 9.48. By determining 

 the Ph values of artificial brines containing each 

 pair of buffers separately it is possible to draw 

 curves from which by interpolation the proper pro- 

 portions of the buffers to yield Pg = 9.48 may be 

 read. This method serves as a cheek of the analyti- 



