156 METALS AND THEIR COMBINATIONS. 



of air), the organic matter suffers decomposition, many volatile 

 products escape, and most of the non-volatile carbon remains mixed 

 with the inorganic portion of the bones, which substance is known 

 as bone-black or animal charcoal. 



Calcium hypophosphite, Calcii hypophosphis, Ca(PH 2 O 2 ) 2 = 

 17O. Obtained by heating pieces of phosphorus with milk of lime 

 until hydrogen phosphide ceases to escape. From the filtered liquid 

 the excess of lime is removed by carbon dioxide, and the clear liquid 

 evaporated to dryness. (Great care must be taken during the whole 

 of the operation, which is somewhat dangerous on account of the 

 inflammable and explosive nature of the compounds.) 



8P + 6H 2 O + 3[Ca(OH) 2 ] = 3[Ca(PH 2 O 2 ) 2 ] + 2PH 3 . 



Calcium hypophosphite is generally met with as a white, crystal- 

 line powder wkh a pearly lustre ; it is soluble in 6 parts of water 

 and has a neutral reaction to litmus. 



Calcium chloride, Calcii chloridum, CaCl 2 = 11O.8, and 

 Calcium bromide, Calcii bromidum, CaBr 2 = 199.6, may both 

 be obtained by dissolving calcium carbonate in hydrochloric acid or 

 hydrobromic acid, until the acids are neutralized. Both salts are 

 highly deliquescent. 



Chlorinated lime, Calx chlorata (Bleaching -powder, incorrectly 

 called Chloride of lime). This is chiefly a mixture (according to some, 

 a compound) of calcium chloride with calcium hypochlorite, and is 

 manufactured on a very large scale by the action of chlorine upon 

 calcium hydroxide : 



2Ca(OH) 2 + 4C1 = 2H 2 O + Ca(ClO) 2 + CaCl 2 . 

 Calcium hydroxide. Chlorinated lime. 



Bleaching-powder is a white powder, having a feeble chlorine-like 

 odor ; exposed to the air it becomes damp from absorption of moist- 

 ure, undergoing decomposition at the same time; with dilute acids it 

 evolves chlorine, of which it should contain not less than 35 per cent. 

 in available form. The action of hydrochloric acid takes place thus : 



Ca(C10) 2 -f 2HC1 = CaCl 2 -f 2HC1O; 

 2HC10 + 2HC1 = 2H 2 + 4C1. 



Bleaching-powder is a powerful disinfecting and bleaching agent. 



Sulphurated lime, Calx sulphurata, is a mixture of calcium 

 sulphide and sulphate, obtained by heating to redness in a crucible a 



