COMBUSTIBLE MINERALS, NOT GASEOUS. 187 



is said to be a mixture of talc and graphite, well suited for some of the uses to which this 

 mineral is applied.* 



Essex County. There is a vein of graphite at Rogers' rock, from which tolerable cabinet 

 specimens may be obtained ; and a locality of the massive variety has been found near Port 

 Henry, but its extent and value are still unknown. 



Putnam County. This mineral, largely mixed, however, with foreign matters, is found 

 associated with arsenical pyrites, near Brown's serpentine quarry, three and a half miles 

 northwest of the village of Carmel. 



Oeange County. Interesting specimens of graphite occur in the white limestone at Duck 

 Cedar pond, in the town of Monroe. The plates, which are often six-sided or rounded, are 

 stellar and radiated, resembling in their structure certain specimens of prehnite. 



New- York County. In the vicinity of the city, graphite has been noticed as occurring in 

 hexahedral prisms about four-tenths of an inch long, and sometimes truncated on their terminal 

 edges. The gangue is a brownish oxide of iron, embracing hornblende and mica.t 



Washigton County. A small vein of graphite occurs in the limestone about a mile and a 

 half from Fort-Ann, on the road to Whitehall. It is associated with rounded grains of quartz, 

 pyroxene and other minerals.| 



Artificial Graphite. A kind of graphite is artificially formed during the reduction of the 

 ores of iron. I have found it in the hearth of a furnace at Southfield in Orange county, and 

 at Rossie in St. Lawrence county. At the former, the magnetic, and at the latter, the specu- 

 lar, iron ore, is employed. The specimen from Southfield has the colour and lustre of gra- 

 phite. It usually breaks with a small conchoidal fracture. It is tougher and harder than 

 graphite, but every where, when broken, has the same lustre and gives the same trace as that 

 mineral. According to my analysis, it is composed of 20.39 carbon and 79.61 iron. On 

 the supposition that this substance contains an atom of each of these constituents, the ratio 

 would be 17.65 carbon and 82 . 35 iron. One of these artificial compounds, examined by 

 Berthier,§ consisted of 0.183 carbon and 0.819 iron, the proportions being quite near to those 

 in the specimen which I analyzed. 



It is known that compounds of carbon and iron in other proportions are thus artificially 

 formed ; and sometimes nearly pure graphite is also the result. 



• Mather. New-York Geological Reports, 1838. % Malher. New-York Geological Rejiorts, 1841. 



f Haiiy. Cleaveland^s Mineralogy. ^ Traite dea Essais par la Vote Seche, II. 210, 



