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The late Dr. Voelcker. 
The subject of this memoir, John Christopher Augustus 
Voelcker, was born on September 24th, 1822, at Frankfort-on- 
the-Maine. He was the fifth son, in a family of seven sons and 
one daughter, of Frederick Adolphus Voelcker, a merchant of 
that city, who died when his filth son was only eleven years 
old. During his years of boyhood, Augustus suffered from very 
delicate health, which greatly retarded his early education. 
This he obtained at a private school in the town. At the age of 
about 22 he went to the University of Gottingen, chiefly for 
the purpose of studying chemistry under Professor Wohler, and 
to work in his laboratory, where perhaps a greater number of able 
chemists have been trained than in any other chemical school, 
even in Germany. The pupils of Wohler, whose laboratory 
maintained its reputation until his death in 1882, are indeed to 
be found in responsible positions in every quarter of the globe, 
and in large numbers in the United States. 
At Gottingen young Voelcker took the degree of Doctor of 
Philosophy in 1846, the subject of his inaugural dissertation 
being the composition of tortoise-shell, which he had investigated 
in the laboratory. From (jiittingen he paid a short visit to 
Giessen ; where Liebig, who almost throughout his career 
carried on investigations conjointly with Wohler, had established 
a school of chemistry, which also brought pupils from all parts 
of the world. Liebig had too, at that time, ior some years paid 
special attention to tlie application of chemistry to agriculture, 
and had already published his two memorable works on that 
subject. 
Whilst Dr. \ oelcker was at Gottingen, he seems to have 
devoted his attention chiefly to the investigation of some of the 
compounds of manganese, nnd of some other metals, for in 1846 he 
published four paj)ers, in (ierman and Dutc:h scientific journals, 
on his experiments on those subjects. In the same year he also 
published, in German journals, a paper on the occurrence of 
mannite in the roots of Triticum repens ; and one oh the 
analysis of poppy-oil. 
It was also whilst he was still at Gottingen, that Professor 
Mulder, the distinguished Dutch chemist, paid a visit to Wohler 
at that place ; and, on Wohler's recommendation, Mulder 
engaged Voelcker as his principal assistant, and he accordingly 
returned with him to Utrecht, where he remained for some 
time. Mulder devoted much attention to certain branches of 
physiological chemistry, especially in their relations to vegetable 
and animal production, and lie embodied the results of his 
investigations in a work published about 1844, which was 
translated into English by Dr. From berg, and brought out in 
partSj commencing in 1845, and which appeared under the title 
