On the Recent Improvements in the Chemical Arts (Paperback)

This historic book may have numerous typos and missing text. Purchasers can download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1851. Excerpt: ... III. METALLURGY. Metalluegy embraces those chemical processes by which metals are extracted from their ores, as well as those by which the crude metal is refined or purified, and may be extended to embrace further operations which have in view the production of alloys, or other modifications, which still present the metallic character. The extension of chemical technology has evolved new processes for extracting metals from their ores, and for producing metallic surfaces and other effects, without the employment of fire, which was an element in former metallurgic processes. These processes being chiefly due to the employment of chemical agents, or the metals themselves in aqueous solution, a distinct branch of metallurgy has arisen, which we term hydrometallurgy, in distinction from the more ancient pyrometallurgy. We have thrown the metals into groups, dependent on their similar mode of occurrence or similar treatment, beginning with iron, which is the most important, and which is exclusively obtained by the reduction of its oxide. Fuel affords heat for breaking up chemical affinities already existing in the native compounds of the ores, and is at the same time the reducing agent for oxides. As ores are never found in a pure state, but always accompanied by foreign matter, this matter is removed by the addition of a flux, which fuses with the foreign matter to a glass or slag (cinder), and is then removed from the metal. On ancient metallurgy and mining in Britain, see an article by J. Phillips, in Phil. Mag. April, 1849, and Amer. Journ. (2) viii. 96-102, 258-263. Carbonic Oxide.--Filhol gives a convenient and economical method of obtaining this gas (Journ. de Pharm. et de Ch. viii. 99), which consists in gently warming a mixture of 1 pt. sugar or starc...