ON DR. JAMES'S POWDER. 



25 



Bat, be the ftaie, whether of mixture or of combination, 

 what it may, my purpofe is to endeavour to produce a fub- 

 ftance, which, from its more certain mode of preparation, 

 ftiay be more equal and conftant in its effects. 



Dilfolve, together or feparately, in the Ieaft poftible portion Newprocefs for 

 of muriatic acid, equal parts of the forementioned white [%££ffi ° f 

 oxide of antimony and of phofphate of lime. * Pour this more conftant 

 folutlon gradually into ,diitilled water, previoufly alkalizated effe£u 

 by a fufficient quantity of ammonia. A white and abundant 

 precipitate will take place, which, well warned and dried, 

 is the fubftitute I propofe for Dr. James's powder. 



The theory of this precipitation is fo clear and fimple, that Remarks, 

 it does not require any comment. It may be .ufeful, how- 

 ever, to thole who with to make this preparation, to remark, 

 that it is abfolutely neceflary that the folution of phofphate of 

 lime and of oxide of antimony, in muriatic acid, fliould, after 

 being well mixed; be poured into, the alkaline liquor, in order 

 to obtain a precipitate homogeneous throughout the opera- 

 tion. For, fliould the alkaline liquor be poured into the acid 

 folution, the water of the former would act upon the entire 

 mafs of oxide of antimony, while the alkali would precipitate 

 the phofphate of lime only as it faturated the acid which 

 held that fait in folution : thus, the precipitate would con- 

 tain more antimony in the beginning; and, towards the end, 

 the phofphate of lime would be predominant. For the fame 

 reafon too, a pure alkali is preferable to its carbonate; for 

 the carbonic acid difengaged, would retain in folution a por* 

 tion of phofphate of lime. 



* In order to procure the phofphate of lime, I diflblved in 

 muriatic acid, a quantity of calcined bone, and precipitated by am- 

 monia, in its flate of greateft caufticity. By this means, the ex- 

 cels of muriatic acid, which held in folution the phofphate cf lime, 

 is faturated, and the phofphate is precipitated; but no muriate of 

 lime is decompoftd, if the ammonia is quite free from carbonic 

 acid. This is the moft direct method of obtaining phofphate of 

 lime pure. This fait is not decompofed, as fome have aflerted, by 

 muriatic acid, but merely diffolved by it. I have been induced 

 to flate fully thefe particulars, becaule, from the beneficial effects 

 of this fait in the treatment of rachitis, as propofed by M. Bon- 

 homme, {Annates de Cbimie, Vol. XVI IT. p. 113,) it may be- 

 come of general ufe. The oxide of antimony, I obtained by pre- 

 cipitating, by water, the common butter of antimony of the (hops. 

 2 ? Whether 



