360 A SHORT HISTORY OF SCIENCE 



MODERN CHEMISTRY. Main features in nineteenth century 

 chemistry are : the discovery of the fundamental quantitative 

 relations of chemical reactions ; the development of a consistent 

 and definite theory of atoms, molecules and valence; the 

 synthesis of organic substances; the discovery of periodic 

 relations and characteristics ; the development of ideas of chemical 

 structure ; the development of electro-chemistry ; the foundation 

 of physical chemistry. 



With Lavoisier, "the father of modern chemistry," the science, 

 heretofore descriptive and empirical, had become quantitative 

 and productive, seeking like the older sciences of astronomy and 

 physics to make itself mathematical an exact science. Postu- 

 lating the existence of indestructible elementary substances, 

 Lavoisier controlled and interpreted chemical reactions by careful 

 weighing. Until he entered the field there was no generalization 

 wide enough to entitle chemistry to be called a science. 



CHEMICAL LABORATORIES : LIEBIG. - - In the nineteenth 

 century chemical studies received a powerful impetus through the 

 establishment of teaching laboratories at the universities in 

 which Liebig at Giessen in 1826 was a pioneer. He writes : 



At Giessen all were concentrated in the work, and this was a passion- 

 ate enjoyment. . . . The necessity of an institute where the pupil 

 could instruct himself in the chemical art, . . . was then in the air, 

 and so it came about that on the opening of my laboratory . . . pupils 

 came to me from all sides. ... I saw very soon that all progress in 

 organic chemistry depended on its simplification. . . . The first 

 years of my residence at Giessen were almost exclusively devoted to 

 the improvement of organic analysis, and with the first successes 

 there began at the small university an activity such as the world had 

 not yet seen. ... A kindly fate had brought together in Giessen the 

 most talented youths from all countries of Europe. . . . Every one 

 was obliged to find his own way for himself. . . . We worked from 

 dawn to the fall of night. 



To investigate the essence of a natural phenomenon, three 

 conditions are necessarv. We must first studv and know the 



v v 



phenomenon itself, from all sides; we must then determine in what 

 relation it stands to other natural phenomena; and lastly, when we 



