1884.] 
421 
The Extraction of Gold. 
of mercury, it meets a strong blast of air which blows it 
across the concentrating chamber. “ The particles of sand 
fall in different parts thereof in accordance with their spe- 
cific gravity, the light waste being conveyed by the air- 
current to a waste-pipe which conduces it away.” 
It will, of course, be evident that as any particle of gold 
combines with the mercury to form an amalgam its specific 
gravity is increased, and it falls down to a conical receptacle 
in the bottom, where it can be let off from time to time as 
convenient. 
It is scarcely necessary to insist on the vast advantages 
of this method of amalgamation over the old wet process. 
The mercury, hot and dry, comes into immediate and close 
contaa with every particle of gold or silver present, which 
can hence scarcely escape without amalgamation. The 
watei is no longer there to interfere or to carry away 
fine films of gold upon its surface, the mercury does not 
become sick, and the whole process is completely under 
control. 
We must, however, beg leave to make one suggestion : 
so far, as we perceive, the inventors purpose using pure 
mercury. We submit that, especially in cases where 
antimony sulphides, &c., are present, they would find it 
advantageous to use the sodium-amalgam, first proposed by 
Mr. W. Crookes, F.R.S., and which has done good service 
in the hands of metallurgists in various parts of the world. 
The quantity of sodium which has to be added is so minute 
that it would neither appreciably increase the working cost 
nor modify the specific gravity, the fluidity, &c., of the 
mercury. Consequently the mechanical arrangements for 
distributing the ground ore through the mercurial column 
would remain the same. 
Passing, however, from considerations of what should or 
must be, to the records of adtual experience, we find the 
teachings of theory fully borne out in practice. In con- 
junction with Messrs. Jordan, Son, and Commans, the 
mining engineers, of 52, Gracechurch Street, the gentlemen 
previously named have had an extensive plant for the 
extraaion of gold ereaea at Stratford Market, and have 
there put their process to the test of work. It has been 
found that the “ Disraeli pyrites,” mentioned above as 
yielding in Queensland, by the old process, i£ ozs. of gold, 
or 30 per cent of the contents as per assay, gives by the 
new process 4 ozs. 5 dwts. 11 grains, or 91 per cent a 
clear gain of nearly 3 ounces. Mr. Joske’s “ Ravenswood ” 
