310 PROCEEDINGS OF THE AMERICAN ACADEMY 



period he was actively engaged in profound scientific labors, the an- 

 nouncement of his latest memoirs scarcely preceding the intelligence 

 of his decease. Few more striking examples have occurred of the 

 preservation and the advantageous employment of intellectual pow- 

 ers of the highest order so far beyond the ordinary term of human 

 Hfe. 



The two renowned chemists, whose names are now removed from 

 our list, Mitscherhch and Rose, are naturally associated. They were 

 born nearly at the same time, studied together under the same master, 

 were Professors throughout the greater part of their lives at the same 

 University, and died within a few months of each other. But with all 

 these external coincidences in the character of their minds and in their 

 influence upon science, they were widely different ; so that, had either 

 been longer spared to us, he would in ho wise have made good the 

 loss of the other. 



EiLHARD MiTSCHERLicH died On the 28th of August, 1863. He 

 was born in 1794, in Neurede, a small town near the German Ocean, 

 in the Province of East Friesland, at that time belonging to Prussia. 

 He finished his chemical studies at Stockholm, in the laboratory of 

 Berzelius, and was shortly afterwards, in 1822, made Professor at the 

 University of Berlin. He here published, in 1829, a text-book upon 

 Chemistry, — a work of much originality, and which has retained its 

 reputation to the present day. 



Mitscherlich's attention was early directed to the connection between 

 crystalhne form and chemical composition; and he had the singular 

 fortune, in his twenty-fifth year, to discover the law which expresses 

 their relation. With this discovery his name has become identified ; 

 and in turn it seems to have given the direction to his thoughts and to 

 the more important of his works. As is usually the case, the way to 

 this discovery was already prepared by the labors of others. It had 

 been laid down by Haiiy as a law, that, with the exception of those 

 substances which crystalHze in the regular system, a difference in 

 chemical composition must necessarily be attended by a difference in 

 crystalline form; and it was thought impossible that the same body 

 could assume two distinct primitive forms. The truth of the former of 

 these views was contested by numerous observers about the beginning 

 of the present century. It was shown as early as 1787 by Leblanc, 

 that from a solution containing the sulphates of iron and of copper 

 crystals may be obtained which have precisely the same form, and yet 



