pyrites, 182 Malachite, 100 Manganese, 246-256 carbide, preparation of, from pyro- gravimetric assay of, 248-252 of Fresenius-Will for, 249–251 commercial value of, 248 removal of, in zinc assays, 211 Mascazzini's process of assay of lead Matt, determination of nickel in, 194 Measuring and weighing samples, 29- 31 assay liquid, 45-47 Mechanical assay of gold by washing, Nickel and cobalt- 160 manipulations, 19-32 Mechernich, treatment of lead matt in, ores, sulphurized and arsen- ores, 182 arsenizing, 183 and fusing, in one opera- colorimetric assay, 198 compounds of, containing an- difficult of solution, 189 containing sulphates not de- de-arsenizing of, by volatiliza- electrolytic assay, 190 reducing and solvent fusion rich in cobalt and refractory, separation of cobalt in, 198 Nickel ores, separation- of nickel and cobalt in, the cobalt arsenide, 186 184 various assays of, 195 wet assay of, 190-198 Patera's process for separating bismuth Peat, composition of, 262 volumetric assay of copper, 124 with small percentage of cop- Perrot's furnace, heat attainable by, 60 per, 187 with zinc, 193 Plattner's assay of, 182-190 solutions, ammoniacal, resistance sulphide (millerite), 182 pyrrhotine, 188 solution from the assay with sul- phocyanide for determining cop- Nitric acid, boiling argentiferous gold decomposition of lead assay. in copper solution, precipita- Nitro-muriatic acid (aqua regia) for Object of the art of assaying, 17, 18 Oker assay laboratory, methods of, 279- 282 Ore balance, 70 Organic combustion furnaces, 63 substances in presence of nitric native yellow, 238 red and yellow, assays for determi- nation of, 238 Orsat's apparatus for examination of furnace gases, 269–272 Oxidized copper ores, 100 substances (lend), 95–97 Oxidizing agents, 78 fusion, 36, 37 or reducing by means of standard Palladium passing with silver into solu gas muffle-furnace, 54, 55 Petroleum, furnaces using the vapors Phosphates of copper, 100 Platiniferous ores, assay of, 179, 180 percentage of platinum in, 179, Pyrites and matt, determination of Riche's process of assay of lead by gravimetric analysis, 100 Richter's mode of determination of the coking quality of coal, 264 Roasting, 32, 33 process for bismuth ores, 226 Rössler, on the loss of gold in cupel- Rothenbach smelting works, process of and solvent fusion of copper ores, Ruby silver, 131 102 fusion, 37 power, estimation of, 77, 78 of various agents, 78 Refining alloys of copper, 109 copper by cupellation, 107 in Mansfeld, 107 on the dish, with borax, 104 with lead and borax (Müsen 1 Rumford, 266 Salt, common, 82 of phosphorus, 79 Saltpetre, 78-81 Salts of lead oxide, 96 preparation of the, 25-29 Samples by rasping, 20 from the heap, 19 measuring and weighing, 29-31 Scheibler's steam apparatus, 26 Schober's volumetric assay of zinc, Schulze's washing apparatus, 28 Schwarz's volumetric assay of copper, Scorification assay for gold, 161 of silver, 132–137 or calcining vessels, 65 Scorifying, small losses in assaying sil- Sefström's furnace, 61 Selenium, precipitation of, by galvanic Separation of auriferous silver grains Silbermann's investigations in regard to alloys, dry assays of, 146-150 wet assays for, 150-158 method for, 146 sweepings, crucible assay of, 139, 140 with platinum, cupellation of, 181, 182 and lead assay combined, 140, 141 determination of percent- nge of, 227 antimonial, 131 assays, accuracy of, 143, 144 bromide, 131 charges for scorification assay in crucible assay of, 137-140 assay of, 147-150 determination of percentage of, by preliminary assay, 147 fine, 147 fire assays for, 132-144 gravimetric analysis for, 158 iodide, 131 loss in assaying, 144 Lower Harz working assay of, 281 non-alloys of, assays for, 131-145 tion assay, 133 ores, 131 precipitation of, by galvanic action, 116 preparation of pure, 82 removal of, in zinc assay, 211 scorification assay of, 132-137 assay, 133-135 telluride, 131 Upper Harz, 23 wet assays for, 144, 145 with lead, collecting, 132-141 Slags, rich and poor, refining of, 109 silver, crucible assay of, 140 |