June 26, 1908] 



SCIENCE 



985 



The conductivity measurements have 

 brought to light a bewildering range of be- 

 havior on the part of the solutions studied. 

 In the first place, it appears that in practically 

 all mixtures into which water enters as one 

 of the constituents of the solvent, the mole- 

 cular conductivities show a minimum value 

 for a certain composition of the solvent. In 

 the second place it is shown that in mixtures 

 of the alcohols, the conductivity follows the 

 law of averages, that is, the conductivity of 

 solutions in such mixtures is usually approxi- 

 mately the mean calculated from the con- 

 ductivities of equimolecular solutions in the 

 pure solvents. Finally, in mixtures of the 

 alcohols with acetone, the molecular con- 

 ductivities generally show a maximum value 

 for certain mixtures. 



These relations, however, hold only in 

 broadest outline; so complex indeed are the 

 observations that it would be useless to at- 

 tempt an account of them in the limits of a 

 review. 



As the result of a long series of measure- 

 ments of viscosity of mixed solvents and their 

 solutions, there has been shown to exist a 

 parallelism between the fluidity — that is, the 

 reciprocal of the viscosity — of a solvent and 

 the conductivity of its solutions, whence it 

 is concluded that electrical conductivity is 

 largely dependent upon the fluidity of the 

 solvent. The parallelism between fluidity and 

 conductivity is shown to be only approximate, 

 however, for upon the effect of fluidity on 

 conductivity is superimposed the effect of the 

 degree of dissociation of the solute and also 

 the size of the sphere of solute which is 

 assumed to be in combination with the ion 

 and to affect the speed with which it travels 

 through the solution. 



The experimental results are discussed at 

 length and hypotheses are offered in ex- 

 planation of the diminished fluidity of the 

 solvent mixtures containing water; of the in- 

 creased fluidity of certain mixtures of the 

 alcohols and acetone; of the approximately 

 normal behavior of mixtures of the alcohols 

 with respect to fluidity; of the obvious de- 

 pendence of electrical conductivity on 



fluidity; of the observed deviations of the con- 

 ductivity curves from the fluidity curves; of 

 the effect of temperature on the conditions 

 prevailing in solutions in mixed solvents; of 

 the effect of the presence of ions of high 

 atomic volume on the viscosity of solvents; 

 and of what seems to be the greater ionizing 

 power of certain mixed solvents over that of 

 either constituent of the mixture. 



Altogether a very extended series of rela- 

 tionships have been discovered and a num- 

 ber of ingenious hypotheses have been offered 

 which are certainly of the greatest importance 

 as contributions to our knowledge of solu- 

 tions. E. C. Franklin 



Elementary Experiments in Psychology. By 

 Gael F. Seashore, of the University of 

 Iowa. Pp. 218. New York, Henry Holt 

 & Co. 1908. 



Had this very valuable manual appeared a 

 few weeks earlier, a notice of it would have 

 been incorporated in the review of Professor 

 Judd's handbooks of psychology (Science, 

 May 15, 1908). Like the Judd volumes it 

 testifies to the increasing need of serviceable 

 handbooks for the presentation of the experi- 

 mental attitude to students of mental 

 processes. Like the Witmer handbook. Pro- 

 fessor Seashore's manual contains within its 

 own covers (with the aid of a few simple 

 properties to be found in every household) a 

 considerable range of experiments illustrative 

 of psychological principles. Unlike the Wit- 

 mer volume, it is not at the same time a 

 text, but merely a companion manual to any 

 text or course. It should be said with the 

 brevity as well as with the emphasis char- 

 acteristic of the book itself that it accom- 

 plishes its purpose with exceptional skill. Its 

 appeal is to a very general clientele. There is 

 hardly a course in psychology so brief or ele- 

 mentary as not to make possible the intro- 

 duction of the experimental method on ths 

 scale provided by Professor Seashore. Let 

 it also be said that while the scope of the 

 work is elementary, its spirit and discernment 

 are sufficiently advanced to arouse in all dis- 

 posed thereto a proper " student " psycho- 



