WOEK OF VAn't HOFF BRUNI. 783 



He was no ordinary collaborator; when, in 1896, he became asso- 

 ciated with the master in the founding of the little private laboratory 

 of Hollandstrasse he had already written, among others, a little book 

 on the phase rule, which is still one of the best on this question, and 

 had already carried out very important experimental work on the 

 affinities of reciprocal pairs of salts, a subject which for problems 

 that he was treating was of the greatest importance. In theoretic 

 questions he was an absolutely independent and original thinker 

 and not always in accord with the master. 



* * * The mother idea of the common work belongs in great 

 part to Meyerhoffer, as van't Hoff has always openly admitted. In 

 his work on reciprocal salt pairs, Meyerhoffer had expressed in 1895 

 the opinion that " the formation of the saline deposits of Stassf urt, 

 Wielicza, and other places, inasmuch as they are of marine origin, 

 can not be explained in a satisfactory manner until one has submitted 

 to a systematic research the solubility and the equilibric comiections 

 which occur among salts which are found in the water of the sea." 



Further, in 1889, in a rectoral discourse at the University of Ley- 

 den, van Bemmelen made allusion to the opportunity of applying 

 the methods in question to the solution of geologic problems. Can we 

 say on that account that van't Hoff brought to this question no origi- 

 nal contribution? Nothing would be more absurd. In 1887, before 

 the work of Meyerhoffer and the allusion of van Bemmelen, he had 

 established the conditions of formation of different salts existing in 

 the layers of oceanic origin, such as the astrakanite, the leonite, and 

 the schonite, and the method of research which has been used to clear 

 up the question is no other than that which he introduced. Meyer- 

 hoffer himself was inspired by his earlier works and had carried out 

 in his laboratory his inaugural work. 



The investigation lasted 10 years, and is set forth in 51 separate 

 . papers, which were all published between 1897 and 1906 in the Pro- 

 ceedings of the Academy of Sciences at Berlin. We should be car- 

 ried too far if we tried to give an idea of them, even a brief one. It 

 is known that the deposits at Stassfurt, which are considered as 

 having been produced by the evaporation of an inland sea, are com- 

 posed essentially of chlorides, sulphates, and borates of sodiimi, potas- 

 sium, magnesium, and calcium, and of all their possible double salts. 

 It was a question of determining the order in which they were depos- 

 ited, the possible interrelations of minerals (what is called paragene- 

 sis) , the limits of temperature and of concentration in which the dif- 

 ferent separations and the various types of paragenesis could take 

 place. In order to solve so complicated a problem, they worked by 

 preference, in determining the solubility at different temperatures, 

 first on pairs of salts, then on all the possible complex systems; to 



