1892-93.] NOTES ON THE AMALGAMATION PROCESS. 3s& 



another ; into opposite ends of the cross fit fork-like prongs which are 

 attached to a spindle, at the top of which is a pinion to which a rotatory- 

 motion is given by a horizontal crown wheel, as many as eighteen being 

 driven in this manner — the power employed being water — by one crown 

 wheel, althouijh there were also small ones in use which a man could 

 work. The front portion of the tub was pierced by two or three holes, 

 in the same line on different levels, through which the sludge at different 

 periods might be withdrawn from within. The substance was ground, if 

 coarser than sand, and concentrated as much as possible ; about two 

 troge (according to Dr. Percy=to from 40 to 50 lbs.) are thrown into 

 the mill and water added, then 40 lbs. of mercury. Grinding now is 

 started, but should the mill be able to take more it is added with suffi- 

 cient water to prevent stiffness. Grinding is continued until the whole 

 is brought to a state of mud, when the top plug in the top hole above- 

 mentioned is now removed and the mud allowed to run off to this level,, 

 when another charge is added ; this is continued until the mercury has 

 absorbed sufficient gold or silver to make it stiff, thus impeding the 

 rotatory motion of the cross, when the tub is emptied of slime and the 

 amalgam taken out, cleaned and dried, and squeezed through a calf- 

 skin bag and distilled ; the distilled mercury always retaining a certain 

 quantity of gold or silver, the retort broken and the silver taken out and 

 melted. The amalgamation process as applied to silver had its primal 

 demonstration on a large scale in Mexico, Chili, and Peru. Dr. Percy,, 

 in his Metallurgy of Gold and Silver, says that Bartolome Medina was 

 generally admitted to be the inventor of the present " Patio proce-ss,'" 

 having invented it in 1557 while a miner at Pachuca in Mexico; the 

 authority for this statement being two documents, one, a report addressed 

 to the Viceroy of Mexico, by Luis Berria de Montalvo, printed in the 

 city of Mexico in 1643, and the other a memoir by Diaz de La Calle to 

 Philip IV., printed in Madrid, 1646, both giving Medina the honour and 

 credit of the invention. Dr. Percy then adds that this statement is not 

 correct, as Don Jose Garces y Kguia, says that the first treatise on 

 amalgamation as then conducted was that of Barba, published in Peru, 

 1639, the process being introduced into Peru by Don Pedro Fernandez 

 de Velasco in 1571. Dr. Percy does not mention when the process was 

 introduced into Mexico, but I have found by consulting the work before 

 mentioned as in my possession, that the process was introduced into- 

 Mexico by the same person (Don Pedro de Velasco) five years before 

 his introduction of it into Peru, namely, in 1566. Now, whether the 

 Patio process was ever introduced into Mexico is a point that might be 

 raised. The enormous amount of gold and silver that had been col- 

 lected and stored by the Caciques that ruled the Aztecs, which was 



