2M 



Analysis of Graphite, 



Article VIL 

 Analysis of Graphite. By Apothecary Schrader.* 



That graphite is a combustible body, composed almost 

 entirely of charcoal, has been long known from the experiments 



Scheele, who first pointed out the method of distinguishing 

 it from molybdena. His experiments were confirmed by the 

 subsequent investigations of Berthollet, Monge, and Vander- 

 monde. These gentlemen put graphite into a glass jar, filled 

 with oxygen gas, and exposed in the focus of Tchirnhouse^s 

 burning-glass. The graphite was speedily consumed, and there 

 remained behind a quantity of iron which had been melted into 

 grains by the heat. Scheele had likewise obtained a residue of 

 iron when he burnt graphite with ten times its weight of salt- 

 petre. 



In these experiments it was observed that the graphite endured 

 a much higher temperature, and required more oxygen for its 

 complete combustion, than the same weight of common char- 

 coal. It was believed, in consequence of the experiments of 

 Guyton, that the carbon in graphite was less oxidized than the 

 charcoal of vegetable bodies. The three above-named French 

 chemists were of opinion tiiat graphite does not burn so easily as 

 charcoal, because it consists of carbon and iron chemically 

 combined together. They conceived that the iron was in the 

 metallic state, and that the carbon was completely saturated 

 with iron. Thus carbon and iron were considered as the 

 constituents of graphite; but it does not appear that any person 

 thought of carefully examining the nature of the ferruginous 

 residue that remains behind after the combustion of graphite. 



I had a particular reason for endeavouring to ascertain all the 

 substances that existed in Spanish graphite, and among other 

 substances I found copper in it. In order to determine wdiether 

 the English graphite would yield the same constituents I made 

 the following experiments : — - 



A. 



In the first place, I picked out of my own collection several 

 very pure specimens of English graphite. From these I obtained 

 the following results : — 



1. As the Spanish graphite had contained a good deal of 

 sulphate of iron and of copper, which could be separated by 

 boiling the mineral in water, I boiled 100 grains of English 



* Frora Der Gesellsdiaft Naturforschender Freunde 211 Berlin Magazine for 

 5810, 1). 205. 



