OF JACKSON, NEW HAMPSHIRE. 321 



evident at our locality, that the oxide of tin was deposited in layers 

 on the sides of the fissured rocks, and that the veins were thus 

 filled up with the oxide by deposition from the sides to the 

 middle. 



This author refers to the sublimation of chloride of iron in the 

 crater of Vesuvius as presenting analogous phenomena. There, 

 as originally observed by M. Gay Lussac, the specular oxide of 

 iron which invests the fissures in the lava, and lines the walls of 

 the caverns, is produced by the sublimation of chloride of iron, 

 which is decomposed by the agency of steam, chlor-hydric acid 

 being formed, and peroxide of iron deposited. 



Remarks on Zinc, Lead, and Copper Ores of New Hamp- 

 shire. By C. T. Jackson. 



It is surprising that the rich veins of blende or sulphuret of 

 zinc, which occur so abundantly in this country should be wholly 

 neglected, when it is so easy to extract the metal from the ore. 

 By roasting the sulphuret of zinc at a dull red heat in a rever- 

 beratory furnace, it is readily converted into the oxide of zinc, 

 which, being mixed with charcoal and distilled, will yield forty 

 per cent, of the metal. A remarkably pure yellow blende occurs 

 in the town of Eaton, N. H. ; and several hundred tons of that 

 ore have been raised dm-ing the working of the mine for lead, and 

 it still remains around the mouth of the mine neglected. 



Black blende also occm-s in large veins in the town of War- 

 ren, N. H., and smaller ones are found at the lead mines of Shel- 

 burne, and in Lyman. 



Assays of Blende. 



Two thousand gi-ains of the Eaton blende having been roasted, 

 and thus converted into oxide of zinc, yielded on distillation 

 seven hundred and seventy-seven grains of pure zinc, or 3S.8 per 



