WOEK OF VAnV HOFF BEUNI. 769 



physicochemical theories to the studies of geological phenomena. In 

 the meantime, in 1901, the Academy of Sciences at Stockholm gave 

 concrete form to the universal opinion of chemists by conferring on 

 him the first Nobel prize for chemistry. 



In the autumn of 190G there appeared the first symptoms of the 

 terrible disease to which he was destined to succomb; after a sojourn 

 in a sanatorium he apparently recovered * * * but a relapse soon 

 followed, and on the 1st of March, 1908, his life ended at Steglitz, 

 Berlin; a life which was too short, if one considers the number of 

 years passed; simple, if one thinks of the tranquility of exterior 

 events; great, as few others, if one reflects on the enormous amount 

 of work which it represents. 



After thus broadly tracing the general biography of this great 

 scientist, we may begin the examination of his life work. And this, 

 with the exception of his first researches in organic chemistry, a few 

 works of fragmentary character, occasional publications and resumes, 

 may be divided into four main divisions : Stereochemistry, the studies 

 of chemical equilibrium, the theory of dilute solutions, and investi- 

 gation on the saline deposits of Stassfurt. The second and third of 

 these chapters overlap in their chronological development and show 

 numerous logical connections with each other. 



The creative period of the stereochemical theory is exceedingly 

 short, lasting but three years, from 1874 to 1877. 



The Dutch paper of 1874 contains in its 14 pages all that is 

 essential. The author points out first that all substances then 

 known which, in a liquid or dissolved state, rotate the plane of 

 polarized light, contain in their formulas at least one " asymmetric " 

 carbon atom — that is, a carbon atom combined with four atoms or 

 groups differing from one another. In seeking the cause of this 

 relation, he remarks that if one imagines the four valences of the 

 carbon atom directed toward the vertices of a tetrahedron, of which 

 the atom itself forms the center, the presence of such an asymmetric 

 atom is the necessary and sufficient cause of the existence of two 

 figures in space, of which one is the mirror image of the other; 

 hence the presence of two isomers, one dextro-rotatory, the other levo- 

 rotatory, and of one inactive compound resulting from the union of 

 both, and capable, by separating, of forming them again. The ex- 

 istence of such isomers and the possibility of separating them had 

 been demonstrated for the first time by Pasteur, 10 years before, in 

 the case of tartaric and racemic acids. 



In this respect the considerations developed two months later by 

 Le Bel agree with those of the young Dutchman, except as to form. 

 But on one point, the latter pushed them further; he foresaw that 

 in unsaturated compounds in which two carbon atoms united by a 

 double bond have their two other valences united with two other 



44863°— sii 1913 40 



