Page 7 Advertisements Column 1

Bruce Herald, Volume VIII, Issue 701, 18 May 1875, Page 7

# A good practical experiment for determining the quantity of gold in pyrites is the following : Weigh a g'ocd average sample of the dry ore— -say about 2lbs — and roast it perfectly siveet (on a shovel over a fire will do), i.e., till no more smell of oreenious and sulphurous acids is perceptible on stirring. Place the roasted mass into an iron mortar, mix it with so much. water that it iust packs or forms a very stiff paste, and add a tablespoonful of quicksilver. The mass has now to be rubbed with, the pestle for so long till all the quicksilver has disappeared, i.e., has been broken up into nearly microscopical particles, which are evenly distributed all throughout. A second similar amount of quicksilver may he worked through in the same way, and then hot water, a, little soda, and a larger amount of quicksilver— about 5 or 6 tablespoonfuls — are added, and the mass gently stirred for some Jime, in order to allow the fine particles of the quicksilver to settle down and unite with the large lot at the bottom just put in. Now follows the careful washing uway of the red oxide of iron-slime in an enamelled iron dish, and ultimately the retorting — at not too Etrong heat — of the whole of tbe auick.oilfei' collected. From the weight of ths gofel left behind — if any— the contents of gold per ton of tho ore can of course easily be calculated. This experiment closely imitates the process to be adopted on tho large scale, and, if carefully executed, gives within go to over 90 per cent, of the fire assay,