on ^bF.* james's powder. £3 



this procefs, it has been fuppofed, that the phofphoric acid of 

 the bone or hartfhorn will faturate, not only the lime with 

 which it was originally combined, but, in addition to it, a 

 new portion of metallic oxide, and a new portion of lime. 

 For, what little fulphuric acid might, during the procefs, have 

 been formed by the combuftion of the fulphur of the crude 

 antimony, is diflipated, at a much lower temperature than 

 that to which the powder is expofed. 



Every oxide of antimony with which we are acquainted, is It contains an 

 volatile at a high degree of heat: it would therefore be "{^timon?* 

 hazardous to affert, that it is poffible to preferve always the 

 fame proportion of antimony, whatever care may be em- 

 ployed in directing the operation ; and, a diffimilarity in the / 

 chemical refult, mult neceiTarily be attended with uncertainty 

 in the medical application. 



To this property may be added another, no lefs conducive and the oxide 

 to error. That portion of oxide of antimony which is not XjjjJ? ,ts 

 volatilized, becomes, in a great meafure, infoluble in all the 

 acids. What the effect of the gaftxic juice may be, upon a 

 fubftance which refiits the action even of nitro-muriatic acid, 

 it is not my purpofe to determine. It is fufticient for me to 

 fay, that, as the quantity of infoluble matter, in a given 

 quantity of Dr. James's powder, prepared at different times, 

 may vary, the effect of any dofe alfo may differ, according to 

 the proportions of foluble and infoluble matter. 



I look upon it as a fortunate circumftance, that thofe ex- Facts in proof, 

 periments and obfervations which I mentioned in the begin- 

 ning of, this paper, exifted as a flandard to which I might 

 refer my own attempts, and by which I might efHmate their • 

 validity. Dr. Pearfon has proved, (as by my own experiments 

 I have found,) that in Dr. James's powder about 23 percent, 

 refitted the action of every acid. In examining fome of the 

 Pulvis Antimonialis of the London Pharmacopeia, I found the 

 average quantity of infoluble matter to be about 44 per 

 cent. This proportion, however, was liable to confiderable 

 variation. * 



* I find, from the information of feveral medical gentlemen, 

 that the Putvis Antimonialis is generally confidered as ftronger than 

 Dr. James's Powder. This feems rather extraordinary, when we 

 cohfider that the quantity of infoluble matter is greater in the former 

 than in the latter ; and would almoft lead us to fufpect it to be thfe , 

 active part of the medicine. 



The 



