b2'l PHILOSOPHICAL TRANSACTIONS. [ANNO 17Q9* 



ingly gave his assistance, and made some experiments, the results of which are as 

 follow. It is to be understood, that a complete analysis was never intended to be 

 made; as neither Mr. H.'s time admitted of it, nor did it appear necessary for the 

 object of the present inquiry. 



Eorper. 1. Some enamel, rasped into a fine powder, was put into a matrass, 

 and, pure muriatic acid being added, the whole was suffered to remain without the 

 application of heat during 1 hour; in the course of this time, the enamel was 

 completely dissolved, with a gentle effervescence. To this solution, some sulphuric 

 acid was gradually added, till all precipitation had ceased: the precipitate was sepa- 

 rated by a filter, and was found to be selenite. The filtrated liquor, by evapora- 

 tion, afforded a small additional quantity of selenite, which was also separated; after 

 which, the liquor, being evaporated, became thick and viscid. This, when diluted 

 with water, precipitated lime from lime-water, in the state of phosphate. To an- 

 other portion, solution of acetite of lead was added, and caused an immediate pre- 

 cipitation of a white matter, which, when dried and sprinkled on burning charcoal, 

 produced a light and smell like phosphorus; it was soluble in nitrous acid, and was 

 thus to be distinguished from muriate or sulphate of lead. 



Exper. 2. Some of the raspings of enamel were dissolved by digestion in nitric 

 acid, and when the solution had been diluted and filtrated, it was saturated with 

 carbonate of ammonia. The precipitate thus produced was collected, and edulco- 

 rated in a filter. The small excess of carbonate of ammonia, in the filtrated liquor, 

 was saturated with acetous acid; after which, the phosphoric acid was precipitated, 

 by solution of acetite of lead. On examining the first precipitate, or that produced 

 by the carbonate of ammonia, it was found that it was still composed of lime, com- 

 bined with a portion of phosphoric acid, instead of carbonic acid, which might 

 have been supposed. To effect therefore a complete separation of the 2 ingredients, 

 lime and phosphoric acid, acetous acid was poured on the precipitate, by which it 

 was immediately dissolved. The whole of the phosphoric acid was then separated 

 from this solution, by acetite of lead; after which, lest any lead should be present, 

 the liquor was saturated with pure or caustic ammonia, and the lead was separated 

 by a filter; lastly, the lime which remained dissolved was precipitated, in the state 

 of carbonate, by carbonate of ammonia. 



The enamel has been supposed, not a phosphate but a carbonate of lime. This 

 error may have arisen from its solubility in acetous acid or distilled vinegar; but 

 the effects of the acetous acid are, in every respect, the same on powdered bone as 

 on the enamel. Consequently, when enamel, or bone, is put into a glass matrass 

 containing acetous acid, placed in a sand bath, the portion which is dissolved, is 

 not, as has been supposed, carbonate but phosphate of lime; for if to the filtrated 

 solution nitrate or acetite of lead is added, a precipitate is produced, of phosphate 

 of lead, in the same manner as when nitrate or acetite of lead is added to urine. 

 This mode of treating substances supposed to contain phosphoric acid, as bone, 

 &c. Mr. Hatchett has found of great utility; because, by this means, he can detect 



