30 



Chemical Composition and Commercial Value of 



the phosphoric acid is united with magnesia and with lime, and 

 the carbonic with lime. The traces of chlorine and sulphuric 

 acid, in all probability, are present as sulphate of soda and 

 chloride of sodium. 



By uniting together the analytical results in the same manner 

 in which the constituents occur in bone-ash, we obtain for the 

 ash of 



In perfectly pure bone-ash thus we find no more than 85-J to 

 86|r per cent, of phosphate of lime and magnesia (bone-earth). 

 It will be noticed that pure bone-ash is much richer in carbonate 

 of lime than the commercial articles, after deduction of sand and 

 other accidental impurities. There is no silica in pure bone- 

 ash, and it is the silica in the shape of fine sand which, driving 

 out carbonic acid from the carbonate of lime, causes the differ- 

 ence in the proportion of carbonate of lime found in pure and the 

 commercial bone-ash respectively. 



After uniting the lime and magnesia with phosphoric acid, and 

 the carbonic acid with lime, it will be seen a considerable quantity 

 of lime remains over. I do not think it probable that all this 

 lime is present in the shape of fluoride of calcium. 



The state of combination in which it may exist, is of com- 



