GEOLOGICAL SOCIETY. 



137 



•ON THE CONVERSION OF SULPHURET OF SILVER INTO NA- 

 TIVE SILVER, AFTER THE METHOD OF BECQUEREL. By Pro* 

 fessor A. Del Rio. 



Read June 1834. 



Becquerel has obtained crystals of galena, similar to 

 those formed in the veins in the humid way,* by taking 

 a liquid and two substances capable of producing an 

 electric current by their mutual reaction. He put into 

 a tube, the calibre of which was five or six lines in dia- 

 meter, some sulphuret of mercury, poured upon it a so- 

 lution of chloride of magnesium, immersed in the liquid 

 a slip of lead to the bottom, and sealed the tube her- 

 metically. A month or six weeks after, he found on 

 the walls of the tube above the sulphuret, a very thin 

 layer of a metallic brilliant precipitate, formed of small 

 crystals, which, observed through the lens, were regu- 

 lar tetrahedrons, like those of the artificial galena, and 

 the mercury was reduced. 



I changed the method of the experiment of Becque- 

 rel, so far as to use sulphuret of silver instead of cinna- 

 bar, and in a month after I observed some reaction, be- 

 cause some magnesia was precipitated, and the border 

 of the slip of lead which touched the sulphuret of silver 

 was tinged red only to the depth of less than one line, 

 which prevented the use of the blow pipe. But as I 

 wished to hasten the process of reducing the silver, I 



* The aqueous formation might be already presumed, at least as far as i» 

 concerned, the galena, which occurs in secondary rocks, as Becquerel has very 

 justly remarked. 



Vol, I.— S 



