CHEMISTRY OF THE WASHOE PEOCESS. 291 



tidn, causing a local electric current, which renders the amalgamating energy 

 of the mercury much more intense. 



Mercury, when perfectly pure, does not apparently possess to so great an 

 extent the power of taking up other metals, or of decomposing mineral com- 

 binations, as when it holds a minute quantity of some foreign metal in solution. 

 The experience among amalgamators in Mexico is that the yield of gold is in- 

 creased by the presence of silver ; also, that the latter metal is extracted with 

 greater facility if a considerable proportion of the amalgam is already present. 

 This opinion is held by most mill-men in Washoe. 



It is stated by some writers upon the question that silver is absorbed 

 with increased activity when copper is employed, and as the former is amal- 

 gamated the latter will be expelled. Both iron and copper cause the forma- 

 tion of copper-amalgam. On the other hand sulphate of copper exhibits a 

 tendency to drive out lead. 



Karsten mentions the property of this salt to purify the mercury from 

 both zinc and antimony. Any one who has witnessed the intensity which 

 sodium-amalgam exerts cannot fail to have been impressed with the rapidity 

 with which it attacks gold, silver, and silver compounds ; yet its application in 

 Washoe in practical operations did not give such results as would warrant its 

 general introduction in the process. 



Although the presence of a small quantity of several metallic bodies en- 

 hances the amalgamating energy of the mercury, yet a slight excess "sickens" 

 it ; that is, it loses its fluidity and becomes dull and inactive. The pecuHar 

 phenomena attending the mercury, by which both electro-positive and electro- 

 negative metals are absorbed, and the efiects which they produce in increasing 

 or neutralizing its action, are very little understood. 



The loss in quicksilver during the operation arises from tvv^o sources ; the 

 one mechanical, the other chemical. The former depends largely upon the 

 manner in which the final washing from the pulp is conducted ; the separa- 

 tion being more or less perfect according to the skill and care with which it 

 is executed. A considerable quantity of the metal, however, is so cut up and 

 ground to such a fine state of division that it is impossible to save it. The 

 chemical loss is occasioned by the formation of the chlorides of mercury, 

 which escape with the tailings. 



