SALTS 0V LIME. 495 



residue in several processes ; a concentrated solution affords 

 crystals in large striated four-sided prisms, which contain 6 eq. of 

 water. Dried with stirring, at 300, it affords a crystalline pow- 

 der, containing 2 eq. water, which produces an intense degree of 

 cold when mixed with snow (page 44.) The crystals are very 

 soluble and exceedingly deliquescent. The salt is made anhydrous 

 by heat, and undergoes the igneous fusion at a red heat. The 

 liquid chloride is poured upon a slab, and the transparent cake 

 of solid salt immediately broken into pieces, and preserved in 

 a stopt bottle. It is much employed, from its great affinity for 

 water, to dry gases and absorb moisture. Chloride of calcium 

 always acquires by fusion a slight but sensible alkaline reaction, 

 from partial decomposition ; on which account Liebig prefers 

 the salt strongly dried, but not fused, as the hygrometric agent 

 in organic analysis. Ten parts of anhydrous alcohol dissolve 7 

 of chloride of calcium, at the boiling point, and the solution, 

 in cold weather, affords crystals in rectangular scales, which 

 are an alcoate, containing about 60 per cent of alcohol, instead 

 of water of crystallization. Anhydrous chloride of calcium 

 likewise absorbs 4 equivalents of ammoniacal gas. 



A solution of chloride of calcium when boiled with hydrate 

 of lime dissolves that substance, and the solution filtered hot, 

 deposits long flat and thin crystals, which contain 49 per cent 

 of water. The empirical formula of this salt is Ca Cl -j- 3Ca O + 

 15 HO. The salt is decomposed by water and alcohol. 



A compound of chloride of calcium with oxalate of lime, con- 

 taining water of crystallization is obtained in good crystals, which 

 are persistent in air, by dissolving oxalate of lime to saturation 

 in hot hydrochloric acid and allowing the solution to cool. It 

 consists of 1 eq. of each salt, with 7 eq. of water. Oxalate of 

 lime is known to combine with 2 eq. of water, of which 1 eq- 

 appears to remain in this double salt, while the other is re- 

 placed by chloride of calcium carrying its 6 atoms of water of 

 crystallization along with it. A similar replacement is ob- 

 served in the formation of quadroxalate of potash (page 172). 

 This salt becomes anhydrous without decomposition at 266 

 (130 cent). It is decomposed by pure water. 



Fluoride of calcium, fliwr spar ; CaF ; 489.8 or 39.25. This 

 salt occurs in nature, massive and in transparent crystals, which 

 are cubes or octohedrons. It is often of beautiful colours, ge- 

 nerally green or purple, and is cut into ornaments. When 



K K 



