128 MEMOIR ON THE SCIENTIFIC CHARACTER 



troublesome processes, including filtration, washing and ig- 

 niting, which ordinarily consume much time, labor, and 

 minute attention. 



As the result of his careful inquiry into the truth of the 

 position assumed, it appears, by Hatiy, without a sufficient 

 examination, Smithson makes the following statement at the 

 conclusion of his paper : 



" No calamine has yet occurred to me which was a real uncombined calx 

 of zinc. If such, as a native product, should ever be met with in any of 

 the still unexplored parts of the earth, or exist among the unscrutinized 

 possessions of any cabinet, it will easily be known by producing a quantity 

 of arid vitriol (anhydrous sulphate) of zinc, exactly double of its own 

 weight ; while the hydrate of zinc, fhould it be found single or uncombined 

 with carbonate, will yield 1.5 times the weight of this arid salt." 



2. In the Phil. Transactions, vol. 96, p. 267, 1806, is an 

 " Account of a discovery of Native Minium" in a letter from 

 James Smithson, Esq., F. R. S., to the Right Hon. Sir Joseph 

 Banks, K B., P. R. S. Read April 24, 1806. 



This letter is dated at Cassel, in Hesse, March 2d, 1806. 

 He states that he has found minium native in the earth the 

 gangue, compact carbonate of zinc with a flaky, crystalline 

 appearance. He gives, in the course of his remarks, the 

 chemical reactions and modes of testing employed to detect 

 its nature. 



" This native minium," he remarks, "seems to be produced by the decay 

 of a galena, wbich I suspect to be itself a secondary production from the 

 metallization of the white carbonate of lead by hepatic gas. This is par- 

 ticularly evident in a specimen of this ore, in one part of which is a cluster 

 of large crystals. Having broken one of these it proved to be converted 

 into minium to a considerable thickness, while its centre is still galena." 



I may remark, in confirmation, that the mineral veins of 

 iron, copper, lead, and silver of the United States, afford 

 abundant evidences of the production of " secondary " 

 ores, such as hydrated peroxides of iron, from the argilla- 

 ceous carbonates, the protoxide and peroxide, and carbonate 

 of copper, from the yellow sulphuret ; the carbonate of lead 

 with its protoxide and peroxide, from galena ; this last be- 

 ing the reverse of the order of change conjectured by 

 Smithson. In the silver mines of North Carolina, now 

 worked with considerable activity, the metallic silver is at 

 the outcrop of the veins found mixed with carbonate of 

 lead and of copper, phosphate of lead, with other materials 

 much disintegrated, and offering great facilities for their 

 extraction, while at greater depths, below the reach of at- 

 mospheric and other surface influences, the body of ore 

 comes to be almost altogether a mass of galena intermixed 

 with metallic silver. 



