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II. Assay of Silver Ores by Heat-Cupellation 39
III. A Table to rectify the Loss in the Silver
X. Assay of Gold Coins, or Alloys of Gold,
XI. To find the Proportion of Gold in a Mixture
XVII. Assay of Iron Ores by Heat................ 103
XVIII. Fuchs's Process for Iron Ores and Iron... 108
XIX. Assay of Ores of Mercury................................................ 111
XX. Assay of Sulphurets in Ores................ 119
TECHNICAL AND SCIENTIFIC TERMS USED.
Alkaline, containing an alkali, viz. potash, soda, or am monia.
Ammoniacal, containing ammonia or hartshorn.
Assays by Heat, or processes by the sole means of fire. Black flux. See Copper Assays.
Carats fine, a term used in designating the value of gold alloys.
Carbonate, applied to oxides, where carbonic acid is united with them.
Chlorides are combinations of chlorine with metals, &c Crucible. See Utensils, &c.
Cupel. See Utensils, &c.
Fluxes, ingredients added to produce slags.
Fuming nitric acid, the strongest kind, emitting red
Galena, a lead ore.
Hygroscopic water, the moisture bodies attract from the atmosphere.
Muffle. See Utensils, &c.
Oil-baths, heated oil, to warm solutions, &c.
Oxidation, the combining with oxygen (rusting, &c.) Peroxide, the oxide containing the greatest amount of oxygen.
Phosphates, combinations of phosphoric acid with metals earths, (earthy,) &c.
Precipitation, the production of insoluble compositions, &c. in wet processes.
Protoxide, containing the least amount of oxygen.
Sand-bath, heated sand, to warm solutions, &c.
Sulphates, combined with sulphuric acid.
Sulphurets, combined with sulphur.
Test-glass, a glass tube closed at one end for chemical
Water-bath, heated water to warm solutions at 212° Fahrenheit.
Water of crystallization, the water contained in crystals, and by evaporating which, they crumble.
Wet processes are those in which acids and solutions are used, and where fire is never directly employed. White flux. See Copper Assay.
ASSAYING is the science which treats of the various methods of ascertaining the amount of one or of several ingredients of a chemical compound, such as an ore or alloy, but is solely intended for practical purposes. For this reason one of its main objects is to be able to attain to a very great accuracy with the smallest and cheapest means, and in the shortest possible time. In this it is contradistinguished from inorganic analytical chemistry, properly so called. The aim of the latter is to ascertain all the different composing elements of an inorganic compound, and also the exact amount of each,