A Manual Of Assaying PDF Download

This historic book may have numerous typos and missing text. Purchasers can usually download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1905 edition. Excerpt: ...height about 4.5 cen Transactions of the American Institute of Mining Engineers, October, 1898. Mr. Chism claims as original the use of silver for receiving mercury (though this was suggested before), and the use of a separate vessel to cool the receiving surface by contact. t See Fig. 39. A, base of retort-stand. B, spirit-lamp. G, retort or annealing-cup. D D, retort stand ring, which serves as support to the apparatus. E E, tin shields. F F, silver-foil for receiving the mercury. O, cooling-cup. tinieters. The mouth of the crucible should have an even surface. Shield.--To prevent the direct heating of the upper part of the crucible and silver-foil, use a circular tin shield about 13 centimeters in diameter, with a hole in the center large enough to pass the crucible partly through, leaving about 1 centimeter of the crucible above the shield. The Recipient.--Use a piece of pure silverfoil (rolled silver) about 5 centimeters square, and about 0.02 millimeters in thickness, on which to receive the mercury. It should be large enough to cover the crucible and leave a margin all round of about one-half centimeter. Cooling-aip.--For cooling the silver-foil, use a silver dish of a wide pattern like an evaporating-dish. Silver is a good heat-conductor. A copper dish could be used. The bottom of the dish should be a little larger than the mouth of the crucible. Keep the bottom of the dish polished to enable you to discover any mercury that might soak through the silver-foil. Should this happen, drive off the mercury from the dish by heat, and repeat the assay with new silver-foil and less ore. Flux.--Use iron filings, the finer the better. They should pass a 60-mesh sieve. Remove most of the grease with strong alcohol, and then heat them to...