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. 1791 Excerpt: ...12.7; clay, 2; siliceous earth, 72; and calx of iron 7.3. $ xiv. The fibrous Schorl of Zilkrtbal. At 7.illerthal in Tyrol is sound a beautisul schorl of a green colour, with prismatic fibres, brittle, transparent, not quite parallel, but combined in several little bundles, diverging from a. centre. Small pieces of it ...
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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. 1791 Excerpt: ...12.7; clay, 2; siliceous earth, 72; and calx of iron 7.3. $ xiv. The fibrous Schorl of Zilkrtbal. At 7.illerthal in Tyrol is sound a beautisul schorl of a green colour, with prismatic fibres, brittle, transparent, not quite parallel, but combined in several little bundles, diverging from a. centre. Small pieces of it cut glass. Cronstedt, s Min. 74. b. Exi. 41. and 42. Whether tried by sire in the crucible, or by the blow-pipe, it discovers the usual qualities of lchorL Exp. 43. By analysis, the centenary produces of terra ponderosa, o; aerated chalk, 9,3; aerated magnesia, 20; clay, 2.7; siliceous earth 64; and calcined iron, 4, Having proceeded thus sar, it may perhaps be not altogether useless to describe more particularly the method by which the disicrent analyses were conducted. The stones intended sor examination being first reduced to the finest powder, and exactly weighed, were thoroughly mixed with fixed vegetable alkali and powdered charcoal, and then ignited sor two hours in a covered crucible; at which period the cover being removed, they were calcined until the charcoal was completely dephlogisticatcd. The steatites alone was not exposed to this process, as its solubility was sussciently proved by other experiments. The alkali employed was the pure salt of tartar. In all the trials, both the quantity and quality of the charcoal being the same, there was no reason to apprehend the admixture of any soreign substance. A centeiwy of this coal yielded no more than 1 j. of asiics. After the calcination, the powders became more or less blue or green, and communicated directly to a small quantity of water poured upon N 3 them them, a green, or bright red. If an acid was poured upon the green liquor, it was changed to a red; it' upon the red liquo...
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