Ziiir Deailccri/jd ion. 



107 



DISTILLATION OF THE ZINC KICII IN SILVEK. 



Weight of alloy per charge with \ lbs. of fine 

 charcoal, ----- 



No. of charges, ----- 



No. of distillations in 24 hours in each retort. 



Total amount of liquated zinc-crusts charged, 

 Charcoal, - - - . - 



Result: Rich lead, - - - 



Metallic scraps, - - - 



Charcoal with little metal. 



Metallic zinc, - - - - 



Blue powder and oxide, 



Coke used, in bushels of 40 lbs., 



Quantity of coke per lbs. of zinc-crust. 



No. 1. 



358 lbs. 

 27 

 2 

 9,525 lbs. 



108 " 

 7,609 " 

 390 " 

 not weighed. 

 770 lbs. 

 not weighed. 

 410.4 

 1.7 



No. 2. 



not 



353 lbs 



20 



2 



6,362 lbs 



80 " 



5,221 " 



weighed 



276 



1.73 



M. Faber du Faur has proposed another furnace, shown in 

 Fig. 14, constructed on the tilting principle, and destined to 

 receive a charge of one ton at a time. The retort, i, is made of 

 fire-clay, lined on the inside with graphite. It is G feet 6 inches 

 long on the outside, 5 feet 10 inches long on the inside, and 

 7 inches high. It is placed on a cast-iron frame, e, protected by- 

 fire-brick, and connects with a condenser, a, 12 inches in diameter 

 and 2 feet 3 inches high on the inside, which is placed on wheels 

 so as to be moved when the retort is to be tilted. The retort is 

 moved mechanically from the fire-place end at /. The fttrnace 

 may be constructed for solid fuel, as in the drawing, but it was in- 

 vented exclusively for the use of gas and hot air. The object in 

 the construction of the retort was, to have the laigest possible 

 surface for distillation, with the shallowest depth of metal, which 

 Avill not exceed 2.^ to 3 inches. It was proposed to make the re- 

 tort in two parts if necessary. This fttrnace has never yet been 

 built, on account of the commercial depression. Contracts for 

 its construction were once prejoared, but not completed. It seems 

 to have the advantage of being able to treat a large quantity ex- 

 peditiously, and thus economize in labor and material. 



The silver lead is cu^Delled in an English cupelle furnace. 



At the Germania works, there are two of these furnaces ; at 

 Cheltenham only one. They are blown with a steam jet in both 

 places. They are usually at work one week, during which time 

 they treat 35 bars of ^h lbs. each per day. The silver is then 

 tapped, and the test changed, or the other furnace used. The 



