CHEMICAL SCIENCE IN AUSTRALASIA. 291 
Corner the first system adopted has given place to smelting to a 
regulus in the first place, and from this the silver is subsequently 
recovered with lead. There are, however, no new adaptations of 
well-known processes to chronicle. As regards the refractory 
silver ores at Webb’s Mine, New England, an ore is being raised 
which consists of a mixture of fahlore, galena, zinc blende, and 
copper pyrites, and this has been subjected to a leaching process, 
modified from Von Patera’s. There are many other localities, 
notably in Northern Queensland, where very refractory ores are 
met with, and which are generally shipped for sale. 
The leaching process does not appear to have been worked 
satisfactorily at Webb’s—at least, operations were suspended, and 
a good deal of discussion ensued as to what was the best method 
to adopt for dealing with the ore. Amalgamation was advocated 
by some, but this has been overruled, and the process about to be 
employed is stated to be Russell’s modification of the Von Patera 
process, in which sodium hyposulphite takes the place of the 
corresponding calcium salt, and sodium sulphide is used asa 
precipitant. There are many advantages in this change, the 
principal, perhaps, of which is that the lead can be precipitated 
as a carbonate, leaving the silver in solution, and although the 
sodium hyposulphite solution is more expensive than the calcium 
hyposulphite one, it can be used in a more concentrated form, and 
the sodium sulphide precipitates a larger proportion of the silver 
than the corresponding calcium salt. This process is about to be 
introduced at the Broken Hill Proprietary Mine to treat some of 
their ores, but the “extra solution,” a double cuprous and sodium 
hyposulphite, which forms one of the features of the Russell process, 
is to be used weaker than specified in Russell’s patent. We believe 
this process to be admirably adapted for the treatment of many of 
the more complex ores in the colonies, and may quote Mr. Stetefelt’s 
resumé of the advantages of this system over pan amalgamation, 
set forth in a paper read before the American Institute of Mining 
Engineers. These are as follows :— 
1. In amalgamation the fineness to which the ore has to be 
crushed is determined by the capacity of the settler to work off 
coarse sands without loss of quicksilver. It is not practicable to 
use a coarser screen than No. 30 if the crushing is done by 
stamps. This is almost equivalent to sifting through a No. 40 
revolving screen, if the crushing is done by rolls. In lixiviation, 
pulverising as coarse as possible is desirable. The limit of coarse- 
ness is determined by the roasting process. It depends upon the 
character of the ore, and, principally, upon the manner in which 
the silver-bearing minerals are distributed in the gangue. 
2. The original cost of the lixiviation plant is much lower than 
that of pans and settlers. A further saving is effected by a 
reduction in the size of the engines and boilers. 
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