NEW EAUTFIY PHOSPHATE. 87 



thefe falts, wafii it in as liiile cold water as poffible, and boii Method of fe- 

 it in a fohition of polafh (o long, till the odour of ammonia is neSfroi^the 

 no further perceptible. The potaQi in this procefs decompofes bones of aai- 

 the phofphates of ammonia and magnelia^ leaving the latter "^^ 

 and phofphate of lime, Tofeparate thefe two, let the whole 

 be boiled in acetic acid, the magnefia u ;!! be ditfolved, and the 

 phofphate of lime remain untouched. 



To obtain the magnefia, let the folution of acetite of mag- 

 nefia be carefully evaporated to drynefs, re-diflblve the fait in 

 water, and decompofe the foIution by carbonate of foda; the 

 precipitate obtained is carbonate of magnefia. If it be pure 

 carbonate of magnefia, it will be completely foluble in ful- 

 phuricacid; if it contains lime, the folution will be cloudy, 

 and a precipitate will gradually be depofited. 



Such is the method we employed for dete6ting and feparat- 

 ing the magnefia contained in the bones of animals ; it is perr 

 haps tedious, but it is eafy and certain. 



The bones of the ox examined in this manner yielded fome- 

 thing lefs than ~ of its weight of fulphate of magnefia, which 

 is equal to about j-^o^ phofphate of magnefia, or in the burnt 

 bone to -'^. 



The bones of the horfe and flieep afforded -^-^ of phofphate 

 of magnefia. 



Thofe of fowls and fiQi yielded nearly the fame quantity as 

 thofe of the ox. 



The re fu Its of a general analyfis of the bones of the ojj: 

 were ; 



Dry gelatine , ,, - 

 Phofphate of lime. 

 Carb. of lime - - - 

 Phofphate of magnefia - 



JOO 

 The prefence of phofphate of magnefia in the bones of ani- 

 mals, and its total abfence in thofe of man, calls upon the phy- 

 fiologift to point out the fource whence this fait is derived in 

 (he former, and why it is not met with in the latter. Tiiat it 

 forms a confiituent part of the food of both, we have proved 

 clfewhere ; that phofphate of lime enters into the compofition 

 of wheat, barley, oats, peas, &c. Why then is it not to be 

 found in the bones of men? The nature of the human urine , 

 may perhaps affift in explaining this problem. We have prove4 



that 



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