GOLD EXTRACTION PROCESSES. 489 



parts of the world, including Wales, Central America, the 

 Pyrenees, and Transylvania. The stamp mill has no doubt 

 been evolved from the pestle and mortar, but was not used 

 for crushing ores until about the year 15 19 when the process 

 of wet stamping and sifting was introduced by Paul Grom- 

 mestetter in Joachimsthal, the two operations, however, 

 being at first kept distinct. 



Agricola has given an exact description of the treatment 

 of auriferous quartz in Germany in 1556, 1 from which it 

 appears that the methods in use at that time were strikingly 

 similar to those still employed in Transylvania and the 

 Tyrol, which were among the districts of which he wrote. 

 Doubtless in these districts the methods have been handed 

 down from generation to generation with little change, while 

 in other countries where they were introduced hundreds of 

 years later the changes have been rapid and striking. In 

 those points in which the older Tyrolean practice differed 

 from the modern one, it resembled the procedure of the old 

 Egyptians. The wooden stamps, shod with hard stone or 

 iron, were arranged in sets of three, and raised by cams to 

 fall by gravity when released. The rock was shovelled dry 

 into the mortar, and coarsely crushed by the blows of the 

 stamps. 



Next it was ground as fine as flour in a stone mill sup- 

 plied with water, and carried by the stream of water into 

 the uppermost of three wooden tubs, whence it overflowed 

 in succession into the other two. Revolving mechanical 

 stirrers furnished with six paddles kept in agitation the 

 contents of the tubs, and "separate even very minute flakes 

 of gold from the crushed ore. These flakes, settling to the 

 bottom, are drawn to itself and cleansed by the quicksilver 

 (lying in the tubs), but the water carries off the dross." 2 

 Agricola here expounds the theory of amalgamation still 

 adhered to in Austria, where mercury is regarded merely 

 as a useful means of collecting particles of gold which have 

 already been separated from the crushed ore by their great 



1 Agricola. De Re Metallica, p. 233. Basel, 1556. 



2 Agricola, loc cit. 



