~Determination of Silver in Copper.~--The silver is best separated in the wet way before cupelling, but if the proportion is not too small, it can be found by cupellation. Weigh up 3 grams of the metal, wrap in 30 grams of sheet lead, and cupel; when the cupellation has proceeded for fifteen minutes, add 20 grams more lead, and continue till finished. Weigh the button of silver. The cupellation loss will be five or six per cent. of the silver present. Determine it by powdering the saturated portion of the cupel and fusing in a large Cornish crucible with 30 grams each of soda and borax, 10 grams of fluor spar, and 1-1/2 gram of charcoal. Cupel the resulting button of lead, and add 10 grams more of lead towards the close of the operation. Deduct the weight of silver contained in the lead used from the weight of the two buttons, and calculate to ounces to the ton. In an experiment in which 0.1975 gram of silver was present, the weight of the button from the first cupellation was 0.1867, and that of the button from the second, after correcting for the lead added, was 0.0110 gram. ~Determination of Silver in Galena.~ _By Pot Assay._--Mix 20 grams of the powdered ore with 30 grams of red lead, 20 grams of soda, and 5 grams of borax, as also with from 7 to 10 grams of nitre. Fuse and pour. Clean the slag if the ore is rich. Cupel the buttons of lead. Make the usual corrections and calculate in ounces to the ton. _By Scorification._--Take 10 grams of the ore, 30 grams of lead, and 0.5 gram of borax. Scorify, clean the slag by adding anthracite after the "eye" has closed in: cupel the button of lead. Weigh the button of silver, make the necessary corrections, and calculate to ounces to the ton. The determination may also be made by cupelling the button of lead got in the dry lead assay. A sample of galena determined by the three methods gave the following results:-- By pot assay 7.18 ozs. per ton. " scorification 7.02 " " lead assay 6.72 " ~Determination of Silver in an Ore.~ _By Pot Assay._--Take 20 grams of the powdered ore and mix with 30 grams of soda, 40 grams of red lead, and 5 grams of borax, as also with from 2 to 3 grams of flour. Fuse: pour. Clean the slag by fusing with 20 grams of red lead and two grams of flour. Cupel the buttons of lead; weigh; make the necessary corrections, and calculate to ounces to the ton. _By Scorification._--Take 5 grams of the powdered ore, 50 grams of lead, and 0.5 gram of "soda" or borax. Scorify. Clean the slag by fusing in a crucible as in the pot assay. Cupel, &c. _Examples._--_By Pot Assay._--Ore taken 20 grams. Silver got 0.2893 gram Silver from slag 0.0060 " Silver lost in cupellation 0.0100 " ------ 0.3053 " Deduct silver in red lead 0.0017 " ------ Silver in ore 0.3036 " = 495.9 ozs. per ton.