ArousT 16, 1907] 



SCIENCE 



213 



so well known to electro-chemists, that but a 

 brief allusion to the contents as a whole is 

 necessary here. The well-balanced chapters 

 deal with the fundamental principles, his- 

 torical development, theory of electrolytic dis- 

 sociation, migration of ions, conductance of 

 electrolytes, electrical endosmose and electro- 

 stenolysis, electromotive force, electrolysis and 

 polarization, a supplement on accumulators 

 and an appendix describing' the scheme of 

 notation employed. 



As to the way in which these are handled, 

 the English is above criticism and the pre- 

 sentation is lucid and comprehensible to the 

 last degree. There is nowhere the slightest 

 chance for misunderstanding the writer's 

 ideas, whether one accepts them as a finality 

 or not. As a presentation of the funda- 

 mental facts and the prevalent theories of 

 electrochemistry, the work is probably with- 

 out an equal, certainly without a superior. 

 As prices go, the book is much cheaper than 

 usual — an additional recommendation, prob- 

 ably ascribable to the broad views and sound 

 commercial instincts of the translators and 

 publishers. 



As to the plan of the work, the theory of 

 electrolytic dissociation is followed con- 

 sistently throughout. We regret to say, how- 

 ever, that although so praiseworthy in other 

 respects, the form of statement in terms of 

 the theory is not always free from objection, 

 and to give the student an unbiased, abso- 

 lutely unobjectionable idea, would need revi- 

 sion by the teacher. To illustrate: "The 

 value 13,700 calories then really represents 

 the heat of dissociation of water" (p. 134). 

 The statement should certainly have been 

 qualified by saying electrolytic dissociation, or 

 even ionization, for dissociation; otherwise, 

 the statement as it stands, is certainly in- 

 correct. 



A series of inconsistencies is caused by fol- 

 lowing in too uncritical a spirit the teachings 

 of the dissociation theory. Thus, on page 94 

 we have: 



The degree of dissociation of a substance in 

 solution is equal to the ratio of its equivalent 



conductance in that solution to its equivalent con- 

 ductance in a solution of infinite volume. 



But on page 148, discussing the di-electric 

 constants of solvents, we have: 



From this fact it follows that it is inadmissible 

 to draw a conclusion, as often has been done, re- 

 garding the degree of dissociation from the value 

 of the equivalent conductance alone. 



Such inconsistencies (and there are others 

 of analogous character) are the chief defects 

 of the book. The tenets of the dissociation 

 theory are laid down with emphasis, usually 

 in italics, as above, and then later the experi- 

 mental facts which negative some of those 

 statements are either not mentioned, or 

 mentioned with very slight emphasis, or else 

 freely admitted, and yet their full import and 

 effect glossed over. There is in many cases 

 an apparent willingness to admit facts con- 

 trary to the tenets of the dissociation theory, 

 and yet such facts are not pushed to their 

 full, legitimate conclusion. 



All of this shows that the theories of 

 electrochemistry are in a state of transition; 

 even the teachers with the best of purposes 

 to see all sides are sometimes staring at one 

 side and blinking at the other. The perfectly 

 judicial attitude of mind is, at present, dif- 

 ficult if not impossible to preserve. A few 

 years will see a new era of electrochemical 

 theory and teaching, wherein the student is 

 nurtured as a plain eclectic, keen to see and 

 quick to admit the truth wherever and in 

 whatever guise he finds it. 



Are we speaking of an unattainable mil- 

 lennium? We hope not. 



Joseph W. Eichards 



Tropical Medicine. By Thomas W. Jackson, 



M.D. 



The acquisition by this government within 

 the last few years of the Philippine Islands, 

 Puerto Rico and the Panama Canal District, 

 and its necessary sanitary supervision over 

 Cuba in its relation to yellow fever, have made 

 the study of tropical diseases one of great in- 

 terest and, especially for the physicians of the 

 southern states, one of practical necessity, for 

 as our knowledge of these so-called tropical 



