SILVER 



815 



place ; h, the ash-pit ; i, the tap-hole ; k, k, the flue, which is divided by partitions 

 into several channels ; I, the chimney ; in, a damper-plate for regulating the draught ; 

 n, a back valve, for admitting air to cool the furnace, and brushes to sweep the 

 flues ; o, tuyere of copper, which by means of an iron wedge may be sloped more 

 or less towards the hearth ; p, the Schnepper, a round piece of sheet iron, hung 

 before the eye of the tuyere, to break and spread the blast ; q, outlet for the glassy 

 litharge. 



Lime-marl has been found to answer well for making the body of the hearth-sole as 

 it absorbs litharge freely, without combining with it. A basin-shaped hollow is 

 formed in the centre, for receiving the silver at the end of 

 the process ; and a gutter is made across the hearth for 

 running off the Gl'dtte or fluid litharge. 



Figs. 1812 to 1814 represent the eliquation hearth of 

 Neustadt. Fig. 1812 is a cr oss -section ; jig. 1813 is a 

 front view; and fig. 1814 a longitudinal section. It is 

 formed by two walls, a, a, 3J feet high, placed from '- to 1 

 foot apart, sloped off at top with iron-plates, 3 inches 



1813 



thick and 18 inches broad, called Saigerscharten, or refining plates, b, b, inclined 

 3 inches towards each other in the middle, so as to leave at the lowest point a slit 

 2% inches wide between them, through which the lead, as it sweats out by the heat, 

 is allowed to fall into the space between the two walls c, called the Saigergasse 

 (sweating-gutter). The sole of this channel slopes down towards the front, so that 

 the liquefied metal may run off into a crucible or pot. Upon one of the long sides, 

 and each of the shorter ones, of the hearth the walls d, d, are raised 2 feet high, 

 and upon these the liquidation lumps rest ; upon the other long side, where there 

 is no wall, there is an opening for admitting these lumps into the hearth. The 

 openings are then shut with a sheet- or cast-iron plate e, which, by means of a chain, 

 pulley, and counter-weight, may be easily raised and lowered. / is a passage for 

 increasing the draught of air. 



Figs. 1815 and 1816 represent the refining furnaces of Friedhricshutte, near Tar- 

 nowitz : a, is the fire-door ; b, the grate ; c, the door for introducing the silver ; d, 

 the moveable test, resting upon a couple of iron rods, e, e, which are let at their ends 

 into the brickwork. They lie lower than would seem to be necessary ;' but this is 



1815 



done in order to be able to place the surface of the test at any desired level, by 

 placing tiles,/,/, under it; g, the flue, leading to a chimney 18 feet high. For the 

 refining of 100 marks of Blicksilber, of the fineness of 15 loths (half-ounces) per 

 cwt., 3 cubic feet of pit-coal are required. The test or cupel must be heated before 

 the impure silver and soft lead are put into it.' 



At these smelting-houses from 150 to 160 cwts. of WerJcblei or work-lead (lead con- 

 taining silver), are operated on at a time. 



Extraction of Silver by Wet Processes. Of late years several wet methods of ex- 

 tracting silver from its ores and from metallurgical products have been so successfully 



