Zinc Desilverization. 99 



graphite retorts in fixed furnaces, as was formerly the case at 

 Bloomfield and Cheltenham, or in Faber dn Faur's tilting 

 furnace. 



At the Germania Avorks, the Flack process was formerly used, 

 but this was abandoned, and they now charge all the zinc scums 

 in a shaft-furnace Avith the drosses from refining and ores of all 

 kinds. The result of this treatment is a rich silver lead, 

 but the greater part of the zinc is lost. From a metallurgical 

 standpoint, this treatment is very objectionable, and should not 

 be imitated ; but the commercial conditions in Utah are so 

 peculiar that it has proved financially successful, owing probably 

 to the great skill with which the process is managed; for a bad 

 process well conducted may sometimes be made successful. In 

 almost every other establishment in the country, the zinc scums 

 are retorted. The retorts used at Bloomfield, N. J., Philadel- 

 phia, Cheltenhnm, and the Germania works, are shown in Figs. 

 8, 9, and 11. They vary but little in different works, and gene- 

 rally are I inch thick on the sides and nearly twice that on the 

 bottom ; the neck is 7 inches long and the body of the retort is 2 

 feet. The diameter at the extremity of the neck is 5J inches, 

 but where it joins the body it is 8 inches. The body in its widest 

 part is 14 inches, but it is only 9 inches at the end. These 

 retorts are made of New Jersey clay and chamotte with 25 per 

 cent, of graphite. They were formerly one of the largest items 

 of cost in the condiict of the operation. 



One of the first furnaces used for the distillation of the zinc, 

 was invented by Mr. "VV. M. -Brodie, and has been constructed 

 in several works. It consists of a large chamber, in Avhich six 

 retorts are placed in two levels, as shown in Fig. 8. These are 

 heated by a fire-place, 2 feet 10 inches long and 16 inches wide, 

 Avith cast-iron grate-bars, which is blown by a forced blast which 

 enters the ash-pit at c, having first been heated in the two hot- 

 air pipes which are placed in compartments above and behind 

 the furnace. The rctoits are protectad fr( m the direct action 

 of the fire by the arches, d. The he.it escapes by the flues aboA'e 

 the retort-chamber, passes into the chamber above, doAvn at the 

 back, and out of the furnace by an underground flue. The re- 

 torts are the ordinary graphite retorts, holding from 450 to 500 

 lbs., so that the furnace would hold from 2,600 to 3,000 lbs. of 



