220 On the Principles Involved in the 



re-smeltings. The slags of the first fusion are usually thrown away, 

 while those of the other two operations contain silver enough to render 

 them worth re-smelting. 



2. Amalgamation of Silver Ores. 



There are two principal methods of amalgamation employed to ex- 

 tract silver from its ores. 



1. The Saxon method, or amalgamation cold, by means of iron. 



2. The Mexican method, or amalgamation cold, by means of a 



mixture of salts. 



There is another method in use in Mexico, but not extensively, it 



is the amalgamation hot, by means of copper. 



The Saxon method, as it is called, was first discovered by a Pe- 

 ruvian miner, Corsa de Leca in 1586, but it was not much employed 

 in Europe until about 1790. The two most important considera- 

 tions in this method are, 



1. To detach the silver from its various combinations in the ore, 

 and bring it to the state of a chloride. 



2. To reduce this chloride to the metallic state by means of me- 

 tallic iron in contact with mercury, so that the silver in its nascent 

 state may combine with the mercury. 



The first operation, after the ore has been properly picked and 

 sorted, is, to form a suitable mixture of the ores, w T ith reference to 

 the quantity of silver and sulphurets contained in them. The amal- 

 gamation succeeds best, when the silver is at the rate of about seventy 

 five ounces to the ton of ore, and the sulphurets amount to about 

 thirty five per cent. The ores after having been assayed, can be 

 mixed so as to give the above proportions. The ore is now powder- 

 ed, and undergoes various mechanical operations with screens, sieves, 

 bolts, &c. until reduced to a very minute state of division. It is now 

 mixed with about ten per cent, of common salt, and roasted in a re- 

 verberatory furnace. The object of the roasting is to change the 

 states of combination of the various substances. Some of the sul- 

 phur of the pyrites burns off, and some combines with the sodium of 

 the common salt. The metals set free by the combination of the 

 sulphur with sodium, combine with the chlorine of the decomposed 

 salt, and form chlorides. Some of the sulphurets are also, perhaps, 

 converted into sulphates and oxides, but the silver, if the operation 

 has been properly performed, is entirely converted to a chloride. 

 During the roasting, the ore must be frequently stirred, and the heat 



