340 ACCOUNT AND DESCRIPTION 



each of the constituent parts of the stone. If circumstances 

 permit, this may be still done, but in the mean time, a few ob- 

 servations, perhaps of some utility, may be offered. 



II. Of the Pyrites. 



In the stones in our possession, very few masses of pyrites of 

 any considerable size are to be found, and they are generally so 

 friable, that it was only with great difficulty, and patience, that 

 20 grains could be collected from 200 or 300 pieces. Their 

 powder is blackish. I digested these 20 grains, tor 12 hours, 

 in muriatic acid, somewhat diluted, hoping to separate the sul- 

 phur, so as to collect it, as Mr. Howard had done. But in this 

 I was disappointed. Only a very few minute portions of sul- 

 phur appeared; they did not, as with Mr. Howard, float, but 

 subsided among the earthy sediment, and only enough of them 

 was collected to decide the existence of sulphur, by their burn- 

 ing with the peculiar smell of that substance. During the so- 

 lution, the smell of sulphureted hidrogen gas was emitted. 

 As the stone, or, at least some parts of it, emits the smell of sul- 

 phur, when heated, I attempted to procure the sulphur by sub- 

 limation. A portion of the powdered stone was placed in a 

 coated glass tube, the upper part of which was kept cold, while 

 the coated part was ignited for an hour, but no sulphur was 

 obtained. 



I caused the gas which arose from the solution of the metal- 

 lic part of the stone, in the sulphuric and muriatic acids, to 

 pass into a solution of caustic potash. Only a small portion of the 

 gas was absorbed ; the potash became slightly hidro-sulphureted, 

 since it precipitated the acitat oi lead, black, and deposited a 

 little sulphur, upon the addition of sulphuric acid. As I had 

 already robbed the specimens of almost every tangible mass of 

 pyrites, and injured them considerably by the extraction, I was 

 compelled to relinquish the idea of obtaining the exact propor- 

 tion of the sulphur. Mr Howard, in the analysis of the stone 

 of Benares, states the sulphur at 2 parts in 14 of pyrites, or 

 about 15 per ct. If we may suppose these pyrites to be of the 

 same composition (and their physical properties correspond with 

 Count Bournon's description)we might deduce the proportion 



