1826.] as carried on in German]/. 267 



the smelting-work take place at the end of each fortnight. 

 The contents of each delivery in fine silver is generally from 

 1100 to 1 200 marks. 



I shall now proceed to describe the washing process, or that 

 practised on the residuum in the barrels after the silver-holding 

 mercury is removed. This body of stuff, as 1 before observed, 

 is passed down into large vats on the ground floor of the build- 

 ing. It consists of the earthy parts of the ore, in which are 

 some small particles of mercury intermixed, and water holding 

 sulphate of soda, and other salts in solution. The main object 

 here is to collect the metallic particles from the mass of ore ; 

 and to effect this, fresh portions of water are added to the stuff 

 discharged from the barrels, and then worked about in large vats 

 or tubs. In each vat works an upright spindle with arms, and 

 attached to the latter by several plates or bars of iron. These 

 vats are furnished with eight plugs one above the other ; so that 

 as the heavier metallic particles subside, the waste or earthy 

 matter may be drawn off at the different plugs in succession, 

 beginning with the top. Those near the bottom are not opened 

 until the mercury there collected is removed, which only takes 

 place once in three or four weeks. The vats are about six feet 

 in diameter at the top, and from five tu six feet in depth. One 

 of these vats is attached to each ranoe of five barrels. The time 

 allotted for the washing process is twelve hours. 



The principal points to which the attention of those conduct- 

 ing this operation is to be directed are, first, the careful exami- 

 nation of the stuff, previous to its being let off at each plug, for 

 particles of mercury : this may be done by diluting a small 

 quantity in a wooden trough. Secondly, so to regulate the 

 quantity of water in the mixture, that the coarser particles of the 

 ore may not subside with the mercury, which will be the case if 

 the stuff be too much diluted ; and at the same time to avoid 

 having the mercury kept in suspension in the mass, which must 

 happen if it be not diluted in a sufficient degree ; for it is 

 evident that unless the particles of mercury be disentangled from 

 the earthy matters, they will not subside by their greater specific 

 gravity, which is the object of the operation. Thirdly, to regu- 

 late properly the velocity of the- machinery; for too quick a 

 motion will prevent the particles of mercury from subsiding ; 

 whilst, if the motion be too slow, the heavier particles of the 

 ore will fall to the bottom with those of the mercury. The 

 reason for having the rods which connect the cross bars of the 

 revolving machine in the vat of iron is, that any mercury which 

 may have been oxidized during the anialaamation process may 

 be reduced to the metallic state, the oxygen possessing a great 

 affinity for iron. A portion of mercury occasionally appears in 

 this last-described process, and the other processes in which it 

 is brought in contact with water, in the form of a white foana 

 floating on the surface. This may arise either from a portion of 



