168 New Apparatus for Reducing Chloride of Silver. 



Aet. XII. — On a New Apparatus for reducing Chloride of Silver, 

 by A. Leilius, Esq., Ph. D., Assayer to the Sydney Branch of 

 the Royal Mint. 



[Read before the Society, 1st December, 1869.] 



In the refinage of gold bullion by Miller's new chlorine process, 

 the silver contained in the alloy thus treated is eliminated from 

 the latter in the state of argentic chloride, which, by a subse- 

 quent process, is reduced to metallic silver. 



This reduction has always been effected in the usual manner, 

 viz., by placing the slabs of fused argentic chloride between 

 plates of wrought iron or zinc, with the addition of acidulated 

 water. Although a perfect reduction to metallic silver has 

 always been achieved, yet it required a considerable amount of 

 time and manipulation, since the thick slabs of fused argentic 

 chloride were, after two or three days, only partially converted 

 into metallic silver, and had to be rearranged in order to expe- 

 dite their complete reduction. Such manipulations, however, 

 were not only found to be very objectionable on account of the 

 time they required, but more so on account of the very disagree- 

 able work which they caused to the operator. The reduced 

 spongy silver was broken up by hand into small pieces, in order 

 to ascertain its complete reduction, and was then boiled in 

 acidulated water to free it from iron or zinc. 



It remained, therefore, a desideratum to effect the reduction 

 of the fused masses of argentic chloride in a manner which 

 would, at the same time, be quicker in its execution, and also 

 obviate the just alluded to manipulations. 



In 1868, Messrs. De la Rue, and Hugo Mueller, in London, 

 constructed a galvanic battery, one pole of which consisted of 

 fused agentic chloride, the thickness of a goose quill ; the other 

 pole of cylinders of zinc. Adopting this principle, I have 

 endeavoured to construct an apparatus which should fulfil the 

 requirements before referred to. 



After operating successfully with a small model, which I have 

 brought here to-night, and which allows the reduction of about 

 250 ounces of argentic chloride in [one operation, I have, with 

 slight modifications, constructed an apparatus which will reduce 

 from 1400 to 1500 ounces of argentic chloride in twenty-four 

 hours. The apparatus and its dimensions are as follows : — 



Two thick boards, 15 inches long, are joined together on both 

 ends by three strong battens, &o as to form an open box without 

 a bottom, 13 inches long by 14 inches wide, and 15 inches high 

 (inside measurement). The two boards forming the length of 

 the box or frame contain seven vertical grooves, half an inch 

 wide and half an inch deep, at intervals of 1^ inch from each 

 other. These grooves are cut down to a length of 12 inches, 



