114 PHOSPHATE OF LIME. 



soil, in almost all plants, and in animal matters. It 

 never occurs free, or uncombined, but always in com- 

 bination with a base, and this is very commonly lime. 

 Thus we always find phosphate of lime in wheat, and 

 all these vegetable substances which constitute part 

 of the food of man and animals ; and we find it in a 

 very considerable quantity associated with carbonate 

 of lime, in the bones of all animals, who obtain from 

 it all the substances on which they feed. Phosphate 

 of lime is insoluble in water, but readily dissolves in 

 solutions containing a little free acid. 



244. Phosphate of lime is easily decomposed by 

 the more powerful acids, such as sulphuric acid and 

 muriatic acid ; in the former case an insoluble sul- 

 phate will be formed, and phosphoric acid left in 

 solution ; and in the latter, a clear solution will be 

 obtained containing phosphoric acid (195) and muriate 

 of lime, a salt which is also very easily soluble in 

 water. 



245. Sulphuric acid does not wholly decompose 

 phosphate of lime, though it takes from it the greater 

 part of the lime which it contains; the phosphoric acid 

 is still combined with a small quantity of lime, con- 

 stituting a bi-phosphate of lime (840) ; the results of 

 the action of sulphuric acid, therefore, are sulphate 

 of lime, a super or bi-phosphate of lime, and free 

 phosphoric acid; the two latter may be readily sepa- 

 rated from the gypsum by the addition of water, they 

 being very soluble, whilst the latter is very little so- 

 luble in that fluid. A mixture of phosphate of lime 



