480 Proceedings. 
sixteen days, and in winter twenty-five days. The way in which the thorough 
amalgamation and separation were afterwards carried on, by means of certain 
machinery, was fully explained by the speaker. Then there was another 
process, by which ores were roasted, and mixed with salt, and placed in 
barrels having certain machinery, for separation and amalgamation. So per- 
fect was this system that a very minute portion of metal was left in the ore. 
"The heat, dews, wet, and the magnetic state of the atmosphere, all played 
a part towards the extraction of the metal from the ore. They might say 
this process was very rough, but if it saved the gold, what mattered it? At 
present, at the Thames, a great part—he might say the greater part—of the 
gold was lost, even with the best machinery. One reason of which, he believed, 
was because the process was gone through far too quickly; and another 
thing that militated against the thorough saving of gold was the immense 
quantity of undecomposed sulphurets that pass through the mills. Speaking 
of the amount of gold that might be extracted from these iron pyrites, Dr. 
Purchas said that in Australia as much as forty ounces to the ton had been 
obtained. 
Captain Hutton said ninety in some places. 
Dr. Purchas said that, if that were the case, there must be an enormous 
quantity of gold lost at the Thames. He was much struck, in reading over 
a book on the subject of gold separating and amalgamating, to find that in 
one mine in California a shaft had been sunk 1,300 feet, and yet, notwith- 
standing the immense depth, the shareholders said that it paid better than 
everit had done before. Even then it was only yielding an ounce to the ton; 
and if this could be done in California, surely it could be done here where 
there was a yield of three or four ounces. Another thing he wished to say 
about the Thames, and that was, that a great deal of the soil that was thrown 
away, in fact, in the majority of cases, contained a large percentage of gold. 
Captain Hutton asked whether the earth was meant, or the casing of the 
veins. 
Dr. Purchas said it would be the casing he was referring to. With regard 
to the processes he had mentioned of getting the gold from the stone, many 
people would grumble at the time taken, but everything of this sort required 
to be done by companies. He thought it was a mistake to attempt to mine 
at the Thames as diggers were doing at the present time ; the right way to 
do it was to mine with companies, and with large areas of ground and proper 
machinery. He believed an immense amount of labour was wasted; cer- 
tainly a large amount of gold was. 
Mr. Gillies said he would not discuss the question of gold saving, but 
= there was one thing which he would ak the Society and the people at large 
` Tot to " large publie companies were always the best. 
