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Author: Admin | 2025-04-28
On these upturned portions place the needle ends. Should the beam not balance properly, trim either end by shaving off very thin pieces until it does. Now divide the strip into twenty equal parts, i.e. ten on each side of the middle, and mark them 1, 2, 3, so that the 1 marks may be nearest the middle and the 10 marks at the ends.Three weights are required:One grain: Can be obtained by weighing out a piece of thin brass wire (ends bent together) on a chemist’s balanceOne tenth grain: To obtain this, place the one-grain weight on the 1 mark of the wooden balance and place such a smaller pieceof wire, bent at the ends on the 10 mark on the opposite side, as will cause the beam to balance properly.One-hundredth grain: To obtain this, place the one-tenth grain weight on the 1 mark, and a piece of thread or such like material on the 10 mark on the other side as will cause the beam to balance properly.To weigh the Button of Gold or SilverPlace it on the 10 mark and see if 1 grain on 10 mark (opposite side) exactly balances it ; if it does, the button weighs 1 grain. If the wire weight be too much, move it towards the middle of the beam to a division, until it is a little lighter than the button. Leave it on this mark. Then take the one-tenth grain, and, commencing from the end of the beam, move it towards the middle until the division reached is that one where this weight together with the first weight is just lighter than the button. Then proceed with the one-hundredth grain in the same way.Suppose, now, that the one grain weight be at 8, the one- tenth grain at 7, and the one-hundredth at 3, the weight of the button is .873 grains, that is, a little more than eight- tenths of a grain. A rule of three sum then determines the amount of precious metal per ton of ore.If a certain weight of ore yields eight-tenths of a grain, how many grains will there be in a ton of similar ore ? (N.B. There are 32 666 troy ounces in one ton.) The number of ounces of precious metal in a ton will be known.DRY ASSAY FOR SILVER AND GOLDIn a gold and silver assay, the precious metals in the sample, either by the scorification or “fusion in a crucible” method, have to be absorbed by lead, and the resulting button of lead containing the gold and silver has to be cupelled in the muffle; the final result being that the precious metals are left on the top of
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