XVI . OBITUARY NOTICES. 



sion of the rational structure of these bases, considering them "as 

 conjugated compounds of sesquioxide, sesquichloride, etc., of 

 cobalt, the five or six equivalents of ammonia, or of ammonia and 

 deutoxide of nitrogen, forming the conjunct, and serving to give 

 to the sesqui-compound of cobalt the degree of stability which it 

 possesses in this class of bodies." This extended and elaborate 

 research has always ranked among the highest chemical investiga- 

 tions ever made in this country. Several years were required to 

 complete it, the analytical portion of the work being as difficult as 

 it was protracted. 



In 1858, in conjunction with Dr. Gibbs, Dr. Genth published a 

 preliminary notice of a new base containing osmium and the ele- 

 ments of ammonia; having been led by their previous work to the 

 study of the production of analogous compounds with other metals. 

 On studying the action of the mixed nitrogen oxides upon ammo- 

 niacal solutions of the platinum metals, they discovered a well 

 characterized base formed by osmium when thus treated, the salts 

 of which crystallize well. Though noticed by Fremy in 1844, he 

 was mistaken in its constitution, calling it osmiamide. The salts 

 of this new base have a beautiful orange- yellow color, are quite 

 insoluble in cold water, more soluble in hot. Their solutions 

 decompose easily, evolving osmic acid. 



Besides the admirable investigations made in pure chemistry, 

 Dr. Genth will ever be remembered for the valuable researches 

 which he made in chemical mineralogy. As early as 1842, while 

 yet a student, he published in Leonhard and Bronri 's Jahrbuch a 

 paper on " A Pseudomorph of Prehnite after Analcime." And in 

 1848, there appears in Liebigs Annalen a paper by him containing 

 analysis of baulite from Krabla, of phillipsite from Stempel, of 

 chabasite from Annerode, of iron-ochre from the Alta-Birke mine, 

 of speiss-cobalt from Reichelsdorf and of uranite from the Siebenge- 

 berge. In 1851, he announced in Keller and Tiedemanti' 's Monats- 

 bericht the discovery .of tetradymite in North Carolina, of traces of 

 platinum in Lancaster county, Pa., and of a magnetic pyrite in the 

 same locality which contained 2.9 per cent, of nickel and which 

 has since been made the basis of an important nickel industry. 

 The same year he described a mineral from Texas, Pa., which he 

 considered to be a gymnite, in which a portion of the magnesia is 

 replaced by nickelous oxide, isomorphous with it. To this mineral 



