774 ANNUAL REPORT SMITHSONIAN INSTITUTION, 1913. 



The scientific production of van't Hojff underwent at this time 

 a period of arrest, due, perhaps, to the loss of tune that the necessity 

 of adapting himself to new conditions of life and work imposed on 

 him, but certainly for the greater part to the intellectual need of 

 concentrating and orienting himself, before starting out again. 

 However that may be, it is certain that during a period of seven 

 years, from 1878 to 1884, he published no original papers worthy of 

 engaging our attention. He did publish, however, a ver}^ interest- 

 ing book, "Ansichten iiber die organische Chemie," now out of print 

 and almost completely unknown, but which has considerable im- 

 portance for one who wishes to follow the evolution of his scientific 

 thought. He described this evolution himself in an address given 

 in Berlin in 1892, which we shall have occasion to mention again 

 more than once. 



He pointed out in this the fact that even liis first works on the 

 asymmetric carbon atom must be considered, from one standpoint at 

 least, as an attempt to contribute to the solution of a problem which 

 had seemed to him from the first and which is in reality the funda- 

 mental problem of general chemistry' — to discover the relations be- 

 tween the chemical constitution of substances and their physical 

 properties and general behavior. 



This problem he set himself to treating in a more general and 

 systematic way in the book we have just mentioned, and then there 

 appeared to him suddenly the great gap which made impossible the 

 rational execution of his vast project; that is, the gap resulting from 

 the almost exclusively qualitative character of the data of organic 

 chemistry, as far as concerns the mechanism of the reactions * * *. 



One single branch w^as developed quantitatively, that of thermo- 

 chemistry; but at bottom the mass of data collected had not led to 

 the great results that had been hoped, and there had been manifested 

 in this field tendencies which were theoretically not rigorous. Besides 

 this there were but few serial relations regarding particular prop- 

 erties, one of the most abundant sources of illusive theories and con- 

 sequent deceptions; and, a much more promising nucleus, some spo- 

 radic instances of quantitative investigations as to the velocity of re- 

 actions and chemical equilibriums. 



Such appeared to van't Hoff the most immediate and the most 

 important goal — to fill up the great gap and try to fuse into one body 

 of knowledge the few and scattered ideas which were possessed up to 

 that time. It was with this intention that he quickly set himself 

 to work, theoretically as well as experimentally. The first results 

 of his researches were not put forth in simple detached monographs, 

 but collected in a harmonious and comprehensive manner in the form 

 of a book entitled " Etudes de dynamique chimique," which saw the 



