28 BONE-ASH. 



all the carbonic acid, and the phosphates of lime and 

 magnesia precipitated by ammonia. When the pre- 

 cipitate has separated, the solution, which contains the 

 lime previously in combination with carbonic acid, is 

 rapidly filtered, and the precipitate thoroughly washed 

 with ammoniacal water. 



From the filtrate, the lime is precipitated by oxalate 

 of ammonia, and the precipitate treated as in No. 12. 



The precipitate of phosphates of lime and magnesia 

 is dissolved in the smallest possible quantity of hydro- 

 chloric acid, and the lime precipitated by neutral oxa- 

 late of potassa. The mixture is digested for some 

 time at a gentle heat, to promote the separation of the 

 precipitate, and the clear supernatant fluid is then cau- 

 tiously neutralized with carbonate of potassa, in order 

 to precipitate the oxalate of lime dissolved by the 

 liberated oxalic acid ; as soon as it has completely 

 separated, the precipitate is filtered off'. From the fil- 

 trate, which contains all the phosphoric acid and mag- 

 nesia, the latter is precipitated by ammonia as phos- 

 phate of magnesia-ammonia, which is treated as in 

 No. 6. 



From the liquid filtered from this precipitate, which 

 must contain free ammonia, the phosphoric acid is 

 precipitated by sulphate of magnesia. 



The very small quantity of fluoride of calcium con- 

 tained in bones can only be detected qualitatively ; 

 in the precipitate obtained by saturating the solution of 

 bone-ash in nitric acid with ammonia. 



Bone-ash may also be analyzed in the following 

 manner : The finely-powdered substance is heated for 

 a long time, nearly to boiling, with an excess of dilute 

 sulphuric acid, the greater part of the water is then 

 evaporated, and the mass mixed with twice its volume 

 of absolute alcohol, which dissolves the phosphoric 

 acid. The mixture is filtered, and the sulphates washed 

 with alcohol. From these the sulphate of magnesia 



