reduced to the Method of Becquerel. 2 IS 



cess nature invests silver glance and red silver ores with native 

 silver in the mines, is a question which I do not pretend to 

 solve. 



In operating upon the fragments of silver glance, which 

 were coated in the preceding experiments with metallic silver, 

 I added a little quicksilver. In fifteen days the ore was trans- 

 formed into an amalgam of silver. The brittle sulphuret and 

 the red silver ore required nearly three weeks for their com- 

 plete amalgamation. According to M. Wohler the carburet 

 of sulphur is decomposable in the same way by diluted nitric 

 acid. I did not succeed in decomposing the dark red silver 

 ore by nitric acid, until after a subsequent saturation of the 

 acid with copper. 



These experiments afford us instances of the reduction 

 of silver ores without common salt, and sulphuret of iron 

 and copper (the magistral of the Mexicans.) I always sus- 

 pected that the "latter substance was very mischievous in the 

 process of amalgamation, occasioning the great loss of silver 

 and mercury which are daily experienced. The silver being- 

 oxidized at the expence of the sulphuric acid, retains its oxy- 

 gen with more tenacity, as lias been shown by M. Berthier, 

 than had been previously admitted; and especially when in con- 

 tact with the oxide of copper, which possesses this property to a 

 high degree. The same probably happens with the mercury ; 

 and the sulphates, bisulphates, and subsuiphates, which arc- 

 thus formed, are lost for ever in the process of washing. 

 Hence, I think, they roast their silver ores in Saxony with 

 common salt alone ; and they treat the chloride of silver by 

 mercury. By this means the loss of mercury amounts only to 

 four ounces per five marcs of silver obtained in the working 

 of ores that contain two ounces per quintal. (See Note A.) 

 How satisfied would we be in Mexico if our loss were no greater.'' 

 I trust that the pupils of the College of Mines of Mexico 

 may derive some advantage from these small experiments of 

 mine. Perhaps I have thus approximated to the discovery 

 made by my lamented pupil Valencia, and which he unfortu- 

 nately carried with him to the grave. I ean state as a fact, 

 that by his genius he had discovered the means of avoiding 

 the loss of mercury termed the cunsiim'ido. Such are the fruits 

 NEW sKiirt's, vol.. v. no. n. OCTOBER HV.il. i 



