300 PROCEEDINGS OF SECTION B. 
and, roughly, 100 gallons were used for each ton of ore roasted. 
The cost of chemicals made up 2s. 64d. per ton of the total cost. 
The sodium sulphide was prepared in the works, being made of 
two parts caustic soda and one of sulphur, boiled with steam to 
assist chemical union. 
The following represents approximately where the silver was 
recovered in the different operations performed in the leaching 
department :— 
In the sulphide precipitate ... 75°78 per cent. of the whole. 
5) Sacarbonatesof lead = "15. 26-31. = 
5,  Wwash-water ... os LOAt =~, 5p 
» vat bottoms ... soe AS te i 
100-00 
The total men employed in the leaching works were as fojlows 
for each day of twenty-four hours :— 
3 chemical mixers. 
3 ore-vat men. 
9 men at filter presses. 
3 precipitating men, 
3 shift bosses. 
20 men removing leached ore. 
Total ee lemen: 
Salt cost 36s. 8d.aton; coal, 34s.; and wood, 14s. a ton. The 
plant cost, on completion, a little over £15,000. 
The Russell extra solution was used some years ago, but no 
apparent benefit was obtained by its use, and it has been discon- 
tinued since about 1893. Taking the hyposulphite process, as a 
whole, it has not been very successful, due to the character of the 
ore and the particular form the silver is found combined in. 
Usually the latter consists of native silver, iodides, and chloro- 
bromides. I do not think pure silver chloride exists in Broken 
Hill ores. Until the chloridising furnaces were built, the process 
had given rather disappointing results. Better results were 
obtained when these furnaces began to work; but then the 
percentage of lead began to rise in the available ores. The car- 
bonate of soda addition to the vat seems to have conquered all 
difficulties until fresh ones turn up. 
Of all the bye-products made from the leaching plant, that from 
the wash-water precipitate has been the most troublesome. As 
the hot wash-water cools, it deposits chloride of lead that is not 
wholly decomposed by the iron scraps, and, when the precipitate 
from the tanks is cleaned up and sent to the smelting plant, heavy 
losses in volatilised chloride of lead is experienced. The most 
