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Of Simple Earths. 5 hence called aerial acid, or fixed air, from its having exifted in a fixed ftate before its expulfion. When this acid is expelled, the earth, uncom- bined with any other fubftance, is then called ltnie, or common or calcareous Urne, to diftinguilh it from othcr earths, which alfo form limes when free from all combinations, viz. the Barytic and Scottifh earths. Ltme, fimply fo called, or calcareous or com mon lime, when unmixed with any other fub ftance, is perfedtly white, and, if in lumps, mo- derately hard and brittle, its (pecific gravitv 2,3. It has a hot burning tafte, corrodes animal, and even vegetable, fubltances in fome degree. When in lumps it heats and burfts by the affufion of water. In the temperature of 6o° it requires between 6 and 700 times its weight of water to diflolve it, but in a boiling heat about \ lefs; but moft of this excefs falls as the water cools, fo that the ftrongeft lime-water contains no more than about one grain per ounce troy : it never cryftallizes while pure. It is combinable with all acids, particularly with the nitrous and marine: 100 parts ftandard nitrous acid take up, when faturated in the tem perature of 6o°, 38,68 of lime; and 100 parts \ me require for their folution 258,5 of ftandard nitrous acid : 100 parts ftandard marine acid are turated by 95,49 of limcj and 100 parts lime require for their folution 104,72 of ftandard marine acid in the temperature of 6o°. Thefe folutions are with difficulty broueht to cryftalhze ; the vitriolic acid fnatches the lime from both of them, and with it forms felenite or gypfum; which, if the folution be faturated, ^ 3 and