THE 

 LONDON, EDINBURGH and DUBLIN 



PHILOSOPHICAL MAGAZINE 



AND 



JOURNAL OF SCIENCE. 



[THIRD SERIES.] 



JANUARY 1850. 



I. Experiments on the Extraction of Gold and Silver from 

 their Ores hy the Wet Way. By John Percy, M.D., F.R.S* 



A TTENTION has of late been directed to the extraction 

 "^^ of silver by the wet way from many of its ores, of which 

 large quantities are now imported into this country, especially 

 from South America. Several processes have been pro- 

 jected; and one, the subject of a patent, is now extensively 

 practised. It consists in calcining the ore with chloride of 

 sodium, precisely as in the amalgamation process of Freiberg, 

 and then dissolving out the chloride of silver formed during 

 the calcination by a hot saturated solution of chloride of so- 

 dium. From this solution the silver is precipitated by me- 

 tallic copper, and then cupelled. I have examined many 

 South American silver ores, and have found them very vari- 

 able in respect to the proportion of silver, and the presence of 

 gold and other metals. In one ore I have found as much as 

 30^ per cent, of fine silver. Several smelting establishments 

 have, I know, attempted to work some of these ores in the 

 dry way, but the results have not been favourable. Hence 

 will appear the importance of directing attention to the ceco- 

 nomic extraction of the silver by the wet way. 



The ore which I subjected to experiment was an auri- 

 ferous silver ore, which contained a large proportion of 

 blende, with galena, iron pyrites and copper pyrites in 

 small quantity ; the non- metallic part of it consisted chiefly of 

 silica. The silver was present as sulphuret. By roasting, 

 the ore swelled up much, and sulphurous acid was copiously 

 disengaged. I received it in the state of coarse brownish- 

 gray powder. I made numerous experiments upon it, to 

 ascertain the best mode of extracting the precious metals by 



* Communicated by the Author, having been read before the Che- 

 mical Section of the British Association at Swansea, 1848. 



Phil, Mag. S. 3. Vol. 86. No. 240. Jan. 1850. B 



