THE CENTURY'S PROGRESS IN CHEMISTRY 



a given mass to a given degree) vary inversely as their 

 atomic weights. In the same year Eilhard Mitscherlich, 

 a German investigator, observed that compounds having 

 the same number of atoms to the molecule are disposed 

 to form the same angles of crystallization a property 

 which he called isomorphism. 



JOHAN JAKOB BERZEHUS 



Here, then, were two utterly novel and independent 

 sets of empirical facts which harmonize strangely with 

 the supposition that substances are composed of chemical 

 atoms of a determinate weight. This surely could not 

 be coincidence it tells of law. And so as soon as the 

 claims of Dulong and Petit and of Mitscherlich had 

 been substantiated by other observers, the laws of the 



261 



