276 MmiNG INBFSTET. 



Mefcal-bearing minerals of common occurrence: blende, galena, argentite, 

 silver, gold, iron pyrites, copper pyrites. 



Minerals of much more rare occurrence : stephanite, polybasite. 



The following experiments were undertaken to ascertain, as far as possi- 

 ble, the action upon the minerals of the Comstock ores, just enumerated, of 

 mercury, and such chemical agents as are employed in the amalgamation pro- 

 cess, or may be formed during the operation in the pan. 



Mercury and native silver, when rubbed together, unite easily. 



Mercury and chloride of silver, the latter prepared in the wet way, when 

 brought in contact, form amalgam and chloride of mercury. 



Mercury and argentite : The mineral was first pulverized and mixed 

 with a little fine sand, the metal added, and the mass allowed to stand for some 

 time; occasionally rubbed together in a mortar. Amalgamation ensued; it 

 was, however, imperfect, much of the mineral being unacted upon. 



Mercury with stephanite and polybasite, under the same conditions as the 

 last experiment, gave similar results ; the decomposition, however, appeared to 

 be more complete, probably owing to the more finely divided state of these 

 minerals than the more sectile argentite. 



The above experiments With native silver, chloride of silver, argentite, 

 and polybasite, were repeated with mercury containing a small quantity of 

 copper-amalgam in solution. In the case of the two former there was the 

 same action as when the pure metal was used; with the two latter the decom- 

 position was more perfect and satisfactory. 



Chloride of silver, argentite, and stephanite were each subjected to the 

 action of mercury and fine metallic iron, with a constant application of 

 heat. The energy displayed by the mercury was much more marked than 

 when employed separately. In the case of the chloride, the decomposition 

 was quite rapid, and the surface of the metal remained bright and clean. 



Chloride of copper and pulverized argentite were allowed to stand 

 together for ten days, in the cold, with an occasional application of heat, at 

 the end of which time, a small quantity of chloride of silver was formed. A 

 trace of sulphuric acid was found in the filtrate. 



Two grammes of the pulverized mineral were also treated with a mod- 

 erately concentrated solution of chloride of copper placed in a bottle, with a 



