902 



SCIENCE. 



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



SCIENTIFIC BOOKS. 

 The Theory of Electrolytic Dissociation and some 

 of its Applications. By Harry C. Jones, 

 Associate in Physical Chemistry in Johns 

 Hopkins University. New York, The Mac- 

 millau Company. 1900. Pp. xii + 289. 

 Price, $1.60. 



For several decades the dominant field in 

 chemistry has been the study of organic com- 

 pounds, and it is only within the last ten years 

 or so that the tide has given evidence of turn- 

 ing in other directions. Chemical theory has 

 been developed very largely in its application 

 to organic chemistry and it is partly at least 

 because these theories have proved inadequate 

 in their wider and more general application that 

 attention is being turned more strongly to inor- 

 ganic chemistry and physical chemistry. There 

 has always been a limited number of chemists 

 who have confined themselves largely to inor- 

 ganic chemistry, but the great impetus in this 

 direction has come from Mendeleef's generaliza- 

 tion of the periodic law, and the consequent 

 necessity of studying closely the relations which 

 subsist between the different elements. So, 

 too, physical chemistry, that is, the study 

 of the physical properties of chemical sub- 

 stances, has always attracted a few investi- 

 gators. Perhaps the most notable workers 

 have been Kopp, who determined and compared 

 large numbers of physical constants of organic 

 substances, and the founders of thermo-chemis- 

 try, Berthelot and Julius Thomsen. But with the 

 work of van't Hoff and Arrhenius was called into 

 being a new physical chemistry, one of the most 

 important fundamental doctrines of which is the 

 theory of electrolytic dissociation, and whose 

 most influential teacher has been Ostwald. The 

 Zeitschrift filr anorganische Chemie and the Zeit- 

 schrift filr physikalische Chemie, as well as the 

 Journal of Physical Chemistry in this country, 

 testify to the activity of the workers in these 

 two newer fields. 



The demands of teachers have also occasioned 

 the production in physical chemistry of a very 

 considerable text-book and reference book of 

 literature, much of it far from satisfactory, as 

 is naturally to be expected in a department of 

 science young as yet, and hence in a very im- 

 mature state. Some of these books attempt a sur- 



vey of the whole field of the older and the newer 

 physical chemistry, some dwell on the new 

 almost exclusively. The book before us is less 

 ambitious, aiming only to treat of a single, 

 though the most important theory of physical 

 chemistry of to- day. In doing this, however, 

 a view of the relation of this theory to the 

 whole field, and of the newer to the earlier 

 physical chemistry is given. Dr. Jones is to be 

 congratulated upon having written a book 

 which, while brief, is clear and is readable. 



The book is divided into four chapters : 

 Chapter I. The earlier physical chemistry, 70 

 pages ; Chapter II. The origin of the theory, 33 

 pages ; Chapter III. Evidence bearing upon 

 the theory, 67 pages ; Chapter IV. Some ap- 

 plications of the theory, 112 pages ; as far as 

 space goes an excellent balance. In the pre- 

 face the author states that these chapters seek 

 to answer respectively the questions: "What 

 was physical chemistry before the theory of elec- 

 trolytic dissociation arose ? How did the theory 

 arise? Is it true? What is its scientific use? " 



Chapter I. takes up first the work done upon 

 the relations between properties and com- 

 position, and properties and constitution. A 

 few pages then outline the development of 

 thermo-chemistry. The next topic is develop- 

 ment of electro-chemical theory ; the later 

 theories of electrolysis, Hittorf's work on the 

 migration velocity of the ions and Kohlrausch's 

 work on the conductivity of solutions, complete 

 the connection between the older and newer 

 physical chemistry, indeed, these last rather be- 

 long to the new. This chapter is completed by 

 the development of chemical dynamics and 

 chemical statics, including the law of mass 

 action, and the work of Willard Gibbs. The 

 treatment of these topics is necessarily brief, 

 but it suffices well to lead up to the main topic 

 of the book. 



Chapter II. It is a curious fact that the 

 origin of some of the great ideas of chemistry 

 must be credited to those who were not chem- 

 ists. The atomic theory, Avogadro's theory, 

 the discovery of the inert gases are examples ; 

 so also the theory of electrolytic dissociation 

 owes its origin to the osmotic investigations 

 of a botanist, W. Pfeffer, working in the field 

 of vegetable physiology. Pfeffer in 1877 



