904 



SCIENCE. 



[N. S. Vol. XI. No, 284. 



thor's own work. Here also is given Thom- 

 son's tlieory of the cause of electrolytic dissocia- 

 tion which while offering a simple explanation of 

 the phenomena, has not as yet been fairly tested 

 experimentally. The nest section treats of the 

 application of the theory to a physical problem, 

 that of the seat of electromotive force in pri- 

 mary cells, and closely connected with this is a 

 review of Ostwald's work on ' Chemische Ferue- 

 wirkung.' Then folio v>'S the closing section on 

 the application of the theory to biological prob- 

 lems with especial reference to the toxic action 

 of ions. 



Such is an outline of the book, whose perusal 

 will well repay anyone who desires to become 

 familiar with the most important phase of mod- 

 ern physical chemistry. It seems ungracious to 

 offer any criticism of a book which limits itself 

 to a definite field and so well carries out its aim, 

 but after reaching the end of the book, one can 

 hardly help feeling that he would like to hear 

 the other side. The author's position is practi- 

 cally that of an advocate, and he makes the 

 best of his ease. It is true that he speaks of 

 diiBculties, but he does not discuss them or 

 even allude to many of them. He says, indeed, 

 "It has already been mentioned, and stress 

 should be laid upon it, that there are facts to 

 which the theory, as we now conceive it, does 

 not seem to apply. But the evidence in favor 

 of the theory is so overwhelming, in compari- 

 son with the few apparent exceptions, that we 

 should examine the latter very closely before 

 concluding finally that they are real excep- 

 tions. Without for a moment ignoring the facts 

 for which the theory does not seem to en- 

 tirely account, the writer believes that the evi- 

 dence in favor of a great generalization being 

 expressed by the theory of electrolytic dissocia- 

 tion is as strong as in the case of many of 

 our so-called laws of nature. For how many 

 of these apply under all conditions, and are 

 entirely free from exceptions." But we wish 

 the author had added a short chapter on these 

 apparent exceptions, for if one reads his book 

 to gain a knowledge of the theory, one desires 

 to hear at least something of objections raised 

 to it. As far as concerns aqueous solutions the 

 theory seems to present an important and very 

 useful generalization and yet it is not even here 



free from difficulties. It is also limited in its 

 field in that it does not account for the fact of 

 solubility, nor answer the questions why this 

 salt is soluble, that insoluble ; and in that it ap- 

 plies only to electrolytes. Again, as soon as we 

 leave the field of aqueous solutions we realize 

 that the present statement of the theory is too 

 narrow. The work of Franklin on liquid 

 ammonia as a solvent presents many phe- 

 nomena wholly inexplicable on the theory of 

 electrolytic dissociation, and work with other 

 solvents raises other difficulties. 



That such advances have been made along 

 the line of this theory, as yet hardly in its 

 teens, is a source of wonder ; but much more 

 remains to be done. The greatest proportion 

 of this work has been confined to aqueous solu- 

 tions, but it is only by extending it to all man- 

 ner of solvents that any comprehensive theory 

 of solutions will be reached. This no one real- 

 izes more than Dr. Jones, who is applying his 

 work to the alcohols and other solvents, and 

 the same is true of other American chemists. 

 Perhaps after all Dr. Jones' book is the more 

 attractive, and even more useful, because its 

 author has posed less as judge than as advo- 

 cate. 



The typography of the book and its general 

 make-up are excellent, the proof has been very 

 carefully read. One excellent innovation has 

 been partially adopted, that of giving the year 

 in addition to the volume in the references to 

 periodical literature. This, while entailing little 

 additional work upon the author, not only 

 lightens materially the labor of one who is 

 looking up the original literature, but it gives 

 the reader a much more definite chronological 

 idea of the subject-matter. The custom should 

 be uniformly adopted in scientific literature. 



The book is provided with a satisfactory 

 index. Jas. Lewis Howe. 



Washington and Lee University. 



An Introduction to Physical Chemistry. By James 

 Walker, D.Sc, Ph.D. London, Macmillan 

 & Co., Limited; New York, The Macmillan 

 Co. 1900. Pp. X + 3-55. Price, $2.50. 

 The author states in the preface that his main 

 object in writing this new work on physical 

 chemistry is to emphasize the important bear- 



