BONE-ASH. 27 



nesia is precipitated by ammonia and phosphate of 

 soda, and from the other potassa by bichloride of pla- 

 tinum. 



12. DOLOMITE AND BITTER-SPAR. 

 CaO, C0 2 ; MgO, C0 2 . 



The mineral dried at 100 is dissolved in dilute nitric 

 acid, the solution afterwards heated, in order to oxidize 

 any protoxide of iron, neutralized with ammonia, heated 

 to ebullition till it no longer smells of ammonia, and 

 rapidly filtered from any precipitate of sesquioxide of 

 iron. The lime is then precipitated by oxalate of am- 

 monia. When the precipitate has subsided, after being 

 digested for some time, it is filtered off, washed, dried 

 and ignited ; it is then moistened with carbonate of 

 ammonia, again dried, and gently heated. It is weighed 

 as carbonate of lime. Or it may be moistened with 

 concentrated sulphuric acid, the excess of acid being 

 expelled by evaporation and subsequent ignition, and 

 weighed as sulphate of lime. 



After the filtered liquid has been mixed with excess 

 of ammonia, the magnesia is precipitated by phosphate 

 of soda, and the precipitate treated as in No. 6. 



The quantity of carbonic acid contained in the min- 

 eral may be determined by loss. It may also be ascer- 

 tained directly by means of the apparatus arranged for 

 the quantitative determination of carbonic acid. 



13. BONE-ASH. 

 3CaO,PO 5 with 3MgO,P0 5 and CaO,C0 2 . 



A mass of white burnt bone is dissolved in dilute 

 nitric acid, the solution digested for some time to expel 



