Cooley's cyclopaedia of practical receipts and collateral information in the arts, manufactures, professions, and trades including medicine, pharmacy, hygiene, and domestic economy : designed as a comprehensive supplement to the Pharmacopoeia and general book of reference for the manufacturer, tradesman, amateur, and heads of families . re also annually collected at Cornwall,being principally a secondary product of theprocess of roasting grey copper ore and whitemundic. The British arsenic works in thatcounty are perhaps the finest in the usual plan is to roast the powdered ore inmuf
Cooley's cyclopaedia of practical receipts and collateral information in the arts, manufactures, professions, and trades including medicine, pharmacy, hygiene, and domestic economy : designed as a comprehensive supplement to the Pharmacopoeia and general book of reference for the manufacturer, tradesman, amateur, and heads of families . re also annually collected at Cornwall,being principally a secondary product of theprocess of roasting grey copper ore and whitemundic. The British arsenic works in thatcounty are perhaps the finest in the usual plan is to roast the powdered ore inmuffle-furnaces; by which its arsenic is con-verted into arsenious anhydride, which escapesas vapour (smelting-house smoke), and passinginto the conden sing-chambers, is depositedin a pulverulent state, forming the flowers ofarsenic, or rough white arsenic, of the smelters,(the giftmehl or poison-flour of the Germans).The crude article obtained in this way is puri-fied by re-sublimation in suitable iron pots orother iron vessels, before it is fit for sale. Itthen forms a semi-transparent vitreous cake,which gradually becomes opaque, and of snowywhiteness, by exposure to the air, and at lengthacquires a more or less pulverulent state on thesurface. In Silesia the crude arsenious anhydrideobtained from arsenical pyrites is refined by. 190 AESENIOUS ANHYDRIDE sublimation as follows :—For this purpose thecast-iron vessels (a) are employed. Upon theseare placed iron rings or collars {b, c, d) and ahood (e), communicating by means of tubes witha series of chambers, of which the first only isshown in i. The flanges of the cast-iron col-lars and all other joints having been tho-roughly luted, the fire is lighted and theheat so increased as to cause the semi-fusionof the arsenious anhydride, which, after cooling,exhibits a peculiarly porcelain-like appearance,at first being as transparent as glass. Prop, Crystals (obtained by careful sub-limation, or by cooling a boiling aqueous solu-tio
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