OF ARKANSAS. 



161 



remunerative. In England, the average quantity of silver contained in 

 the lead which is worked for silver, is 7 or 8 ounces per ton, or about G or 

 7 ounces per ton of galena.* The galena, from the mines of the ''Middle- 

 town Silver and Lead Mining and Manufacturing Company," in Connecti- 

 cut, contains from 25 to 75 oz. of silver to the ton (of 21 cwts) of lead. 

 The galena from the « Washington mine," North Carolina, contains only 

 7.5 oz. of silver in the ton (average of 200 assays). * 



ORES OF MANGANESE. 



Of the five specimens of ores of manganese, subjected to analysis, two 

 (Xos. 20 and 21) were collected on the spot; the other three, I received 

 from a gentleman in Batesville, who collected them at the localities below 

 mentioned. 



No. 20 Psilomelane, from the main manganese mine, two miles above 

 West fork of Lafferty creek, Independence county: 



Massive; lustre submetallic; color between dark steel-gray and iron- 

 black; hardness 5.5; fracture subcrystalline, hackly, somewhat resembling 

 the fracture of cast iron; brittle; strikes fire with steel; powder reddish* 

 brown. 



Before the blowpipe, infusible alone; on charcoal in reduction flame 

 becomes reddish-brown; in a matrass, yields water; with fluxes, gives the 

 manganese reactions. Dissolves in hydrochloric acid with evolution of 

 chlorine, leaving a small residue of silica. 



Occurs in veins traversing the encrinital beds of the cavernous limestone. 



Composition, dried at 250 deg. F: 



Manganoso-manganic oxide (Mn 3 4 ) 91.367 



Silica 2.845 



Bar yta 0.512 



Lime trace 



Water and oxygen, expelled by heat 5.931 



100.655 

 The air-dried mineral lost 0.53 per cent, of moisture at 250 deg. F, 



See J. D. Whitney's "Metallic W^lth of the United States." Philadelphia, 1854 

 11 



