
Troemner Assay Ton Weight Set  WEIGHT SET V  Set of 7 assay ton weights with tweezers, includes 4, 2, 1, .5, .2, .1, and .05 A.T. in wooden box 3 3/4 in. L x 1 3/4 in. D x 1 3/4 in. H, marked on box end HENRY TROEMNER PHILA, mahogany wooden box with lid [In the United States, assay offices commonly use troy ounces of precious metals per ton of sample for the unit of measure. To simplify the mathematics of various conversions to calculate this unit, the assay ton is used. The assay ton (abbreviated A.T.) is not a unit of measurement but rather a standard quantity of mass or weight used in the assaying of precious metals. The assay ton contains as many milligrams as a ton contains troy ounces. Since there are 2000 pounds avoirdupois per ton, 7000 grains per pound and 480 grains per troy ounce, then there are 29166.7 troy ounces in a ton. If the amount of ore used for a fire assay is a one assay ton sample, then the weight of the sample in grams is 29.1667 or 29166.7 milligrams. The resulting precious metal bead after fluxing, and cupelling to remove the lead, copper and other impurities, is weighed on an assay balance with accuracy to tenths or hundreds of milligrams. Each milligram of weight is equal to one troy ounce of precious metal per ton of sample. For example, if one assay ton sample of gold ore (29.1667 grams) is processed resulting in a bead that weighs 3 milligrams, then the ore would assay at 3 troy ounces per ton.]  Original Image 
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