GEOLOGICAL SOCIETY OF PENNSYLVANIA. 223 



internal fracture is conchoidal, and the colour reddish 

 brown. The addition of an acid, when aided by a slight 

 heat, causes a lively effervescence, and like the preced- 

 ing variety, a black organic powder is left, which en- 

 tirely disappears when acted on by nitric acid. The 

 ferrocyanite of potash throws down from its solution, a 

 voluminous blue precipitate. 



Silidous Iron Ore, from Blossburg. 



This ore has a dark brown colour ; when pulverized, 

 its powder is dirty white. The fracture is rough and 

 uneven. The action of the acids upon this ore is fol- 

 lowed by effervescence, the precipitation of bituminous 

 matter, and an insoluble silicipus residuum. We should 

 here observe, that these iron ores, as well as others that 

 we have examined from different parts of the Pennsyl- 

 vania coal fields, contain little or no lime. It was ray 

 intention to have furnished a quantitive analysis of these 

 ores, as my friend Mr Taylor desired ; but my late visit 

 to the gold region of Virginia having detained me longer 

 than I expected, I am under the necessity of giving this 

 imperfect account, which, however vague, I hope will 

 suffice to give some idea of the nature of these iron ores. 



No. 6. 



Coal Mine, Coal run. 



Has a semivitreous lustre ; is black, and very brittle; 

 fracture uneven, and yielding a black powder. This 

 coal is very fat, burns with a long fuliginous flame, leav- 

 ing a voluminous coke, which, when incinerated, yields 

 a grey ash, free from lime. 



Carbon, ....... 75.4 



Volatile matter, 16.4 



Cinders, 8.2 



100.0 



