CALCIUM. 135 



in the phosphatic rocks, is sold as acid phosphate or super- 

 phosphate. 



Bone-black and bone-ash. Phosphates enter the animal system 

 in the various kinds of food, and are to be found in every tissue 

 and fluid, but most abundantly in the bones and teeth. Bones 

 contain about 30 per cent, of organic and 70 per cent, of inor- 

 ganic matter, most of which is tricalcium phosphate. When 

 bones are burned until all the organic matter has been destroyed 

 and volatilized, the resulting product is known as bone-ash. 

 If, however, the bones are subjected to the process of destruc- 

 tive distillation (heating with exclusion of air), the organic 

 matter sufters decomposition, many ' volatile products escape, 

 and most of the non-volatije carbon remains mixed with the in- 

 organic portion of the bones, which substance is known as bone- 

 black or animal charcoal. 



Calcium hypophosphite, Calcii hypophosphis, Ca2(PH 2 2 ) = 170. 



Obtained by heating pieces of phosphorus with milk of lime 

 until phosphoretted hydrogen ceases to escape. From the fil- 

 tered 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 + 3(Ca2HO) = 3(Ca2PH 2 O 2 ) + 2PH 3 . 



Chlorinated lime, Calx chlorate (Bleaching-powder, incorrectly 

 called Chloride of lime}. This is chiefly a mixture (according to 

 some, a compound) of calcium chloride with calcium hypo- 

 chlorite, and is manufactured on a very large scale by the action 

 of chlorine upon calcium hydrate: 



2(Ca2HO) -f 4C1 = 2H 2 O + Ca2ClO -f CaCl 2 . 



Calcium hydrate. Chlorinated lime. 



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

 like odor; exposed to the air it becomes damp from absorption 

 of moisture, undergoing decomposition at the same time; with 

 dilute acids it evolves chlorine gas; it is a powerful disinfecting 

 and bleaching agent. 



