852 REPORT—1905. 
control over the forces of Nature might have been delayed for centuries, or perhaps 
for ages. For iron has been man’s chief material instrument in the conquest of 
Nature; without it the energy alike of the waterfall and of the coalfield would 
have remained uncontrolled and unused. In this conquest of the resources of 
Nature for the service of man are we not entitled to say that the intellectual 
and social gains have equalled, if they have not exceeded, in value the purely 
material gains; and may we not then regard iron as the symbol of a beneficent 
conquest of Nature ? 
With the advent of the Industrial Age gold was destined to take a new place 
in the world’s history as the great medium of exchange, the great promoter of 
industry and commerce. While individual gain still remained the propelling 
power towards its discovery and acquisition, every fresh discovery led directly or 
indirectly to the freer interchange of the products of industry, and thus reacted 
favourably on the industrial and social conditions of the time. 
So long as the chief supplies of gold were obtained from alluvial deposits by 
the simple process of washing, the winning of gold almost necessarily continued 
to be pursued by individuals, or by small groups of workers, who were mainly 
attracted by the highly speculative nature of the occupation. These workers 
endured the greatest hardships and ran the most serious personal risks, drawn on 
from day to day by the hope that some special stroke of good fortune would be 
theirs. This condition prevailed also in fields in which the reef gold occurred 
near the surface, where it was easily accessible without costly mining appliances, 
and where the precious metal was loosely associated with a weathered matrix. 
These free-milling ores could be readily handled by ctushing and amalgamation 
with mercury, so that here also no elaborate organisation and no great expenditure 
of capital were necessary. A third stage was reached when the more easily 
worked deposits above the water-line had been worked out. Not only were more 
costly appliances and more elaborately organised efforts required to bring the ore 
to the surface, but the ore when obtained contained less of its gold in the easily 
recovered, and more in the refractory or combined form. The problem of 
recovery had now to be attacked by improved mechanical and chemical methods. 
The sulphides or tellurides with which the gold was associated or combined had 
to be reduced to a state of minute subdivision by more perfect stamping or grind- 
ing, and elaborate precautions were necessary to ensure metallic contact between 
the particles of gold and the solvent mercury. In many cases the amalgamation 
process failed to extract mcre than a very moderate proportion of the gold, and 
the quartz sand or ‘ tailings’ which still contained the remainder found its way 
into creeks and rivers or remained in heaps on the ground around the batteries, 
In neighbourhoods where fuel was available a preliminary roasting of the ore was 
resorted to, to oxidise or volatilise the baser metals and set free the gold; or the 
sulphides, tellurides, &c., were concentrated by washing, and the concentrates 
were taken to smelting or chlorinating works in some favourable situation where 
the more elaborate metallurgical methods could be economically applied. Many 
efforts were also made to apply the solvent action of chlorine directly to the 
unconcentrated unroasted ores ; but unfortunately chlorine is an excellent solvent 
for other substances besides gold, and in practice it was found that its solvent 
energy was mainly exercised on the base metals and metalloids, and on the 
materials of which the apparatus itself was constructed. 
This to the best of my knowledge is a correct, if rather sketchy, description 
of the state of matters in 1889 when the use of a dilute solution of cyanide of 
potassium was first seriously proposed for the extraction of gold from its ores. 
Those of us who can recall the time will remember that the proposal was 
far from favourably regarded from a chemical point of view. The cost of the 
reagent, its extremely poisonous nature, the instability of its solutions, its slow 
action—such were the difliculties that naturally presented themselves to our 
minds, And, even granting that these difficulties might be overcome, there 
still remained the serious problem of how to recover the gold in metallic form 
from the extremely dilute solutions of the cyanide of gold and potassium. How 
each and all of these difficulties have been swept aside, how within little more 
