DECOMPOSITION OF PHOSPHATES BY CHARCOAL gg^ 



b€ presumed therefore, that they failed either because they 

 did not deprive this salt of its water of crystallization, or 

 because they did not employ a degree of heat much beyond 

 what is necessary for obtaining phosphorus from free phos- 

 phoric acid. 



Sect. 4< DecompositUm of Phosphate of Lime by Charcoal, 



I mixed an aqueous solution of nitrate of lime with phos- Ph^sphatf of 

 pboric acid, and precipitated the solution with ammonia, ^""**^*^"^'"' 

 which separated from it the pl)osphate of lime. Of this coal. 

 salt, well washed, powdered, and dried at a red heat, 10 

 gram. [154 grs,] were mixed with twice their weight of 

 beech charcoal powder, which had previously been boiled 

 in a large quantity of water to deprive it of potash. 



The degree of heat employed in the preceding operations 

 was not sufficient to render the result of this very decisive. 

 I therefore gave up all thoughts of extracting the phospho- 

 rus by distillation in the furnace above described : and put 

 a similar mixture of charcoal and phosphate of lime into a 

 Hessian crucible, closed with a platina cover, and surrouad- 

 ed with charcoal powder in another crucible closed wiih an 

 earthen cover. This apparatus was exposed for two hours 

 to the action of a wind furnace, which produces the highebt 

 degree of heat, that Wedgwood's pyrometer wil! indicate. 

 The interior crucible was not altered, but its platina cover 

 was fused. The earthen cover remained entire. The resi- 

 duum of the mixture of phosphate with charcoal was di^ 

 gested in muriatic acid. The solution, filtered and precipi- 

 tated successively with ammonia and carbonate of ammonia, 

 yielded to the former 4'52 gram. [70 grs.] of pho. phate of 

 lime dried at a red heat, and to the second 5*22 gram. [80 

 grs.] of carbonate of lime. The result bhows, that about 

 half the phosphate of lime was decomposed by the charcoal, 



1 repeated the preceding experiment on native phosphate Native i>ho<». 

 of lime, the transparent Spanish chrysolite in regular crys- p'^ate mors 

 tah *. As the elements of this substance are niucli more j.Q,„p'.j^^„° ^*' 



* Mr. Vauqnelin has found, that lOO parts of cbrysolite contain 

 53-S of Ume, and 45-7 of phosphoric ariJ. 



condensed 



