•Ji; The ratio and Cazo Process. 



pile would become too cold. Tails, or any other sand free from 

 soluble substances, can be used ; but these are open to the ob- 

 jection that they increase the bulk without increasing the yield 

 of the torta. When the heat is not too great, it can sometimes 

 be cured by the application of cold water; but care must be 

 taken not to add so much as to thin the pulp. Cold working- 

 means simply that the operation does not proceed quickly enough, 

 and that an insufficient quantity of magistral has been added to 

 the pile. If left in this state, a large quantity of mercury would 

 be lost as oxide of mercury. To ascertain exactly what is to be 

 done with the torta when in this state, assays of from 1 to 3 

 kilos., ijaclas, are taken, and what is required added according 

 to the indications which they give. 



Many amalgamators prefer to work the 'torta rather hot. 

 When it is manifestly too hot, they allow it to remain per- 

 fectly idle for a few days, taking assays all the time to ascer- 

 tain when it gets back to the proper condition. They add 

 nothing to the pile in the meantime, and when it has come 

 back to its normal condition, go on as if nothing had happened. 

 They think that they gain time and do not lose any more quick- 

 silver than if they worked faster, and that they get a larger yield 

 of the precious metals. In the winter season a little less sulphate 

 of copper is required than during the summer. They generally 

 begin to diminish the quantity of the reagent in September. 



There have been a great many theories in regard to the action 

 of these reagents, and a great many investigations of them, 

 which can hardly be said to have cleared up many of the obscure 

 points. A resume of what has been done is given below, which, 

 however, is not very satisfactory, and does not throw much light 

 on the subject. Some of the j^ublished reactions, after careful 

 trial, could not be obtained. The reactions given below have 

 been compiled in the hope that some one may be led to make a 

 more careful examination of the whole subject. 



The amalgamators suppose that the chloride of sodium cleans 

 the silver and the sulphate of copper heats it, and that the amal- 

 gam of silver and mercury results. The mercury lost is counted 

 as lost mechanically ; the amount of loss being about equal in 

 weight to that of the silver extracted. 



The generally received theory is, that the salt and the sulphate 



