2$ on dr. james's powder, 



IV. 



Obfervations and Experiments upon Dr. James's Powder, xvitk a 

 Method of preparing, in the humid Way, afimilar Subftance. 

 Bj/ Richard Chenevjx, Esq. F.R.S. M.R.I. A.* 



A 

 Preliminary re- -t^FTER the obfervations and experiments made by Dr. 



Pearfon, to inveftigate the nature of Dr. James's powder, and 

 prefented by him to this Society, very little remained to be 

 effected or defired, towards a further knowledge of the fub- 

 je<5t. But thofe very experiments ferved to fuggeft, that the 

 mode of preparation was far from being the beft that the 

 prefent improved ftate of chymical knowledge might afford ; 

 and that, in all probability, a lefs defective compofition might 

 refult from a procefs more conformable to fome improvements, 

 which of late have been advantageoufly applied to pharma» 

 ceutic chymiftry. 



It may be laid down as a general principle, that, in de- 

 licate experiments, whether analytical or fynthetical, fire 

 (that potent and once believed to be univerfal agent) is too 

 precarious in its means, and too uncertain in its application, 

 to be employed with full and conftant fuccefs. And, if it is 

 ftill recurred to, the advantage of promptnefs, and a remnant 

 of ancient cuftom, are the principal reafons. But, where 

 other methods can be devifed to effect the fame combinations, 

 (and the humid way offers many,) every perfon converfant in 

 chymical knowledge will allow the benefit of adopting them. 

 The recent improvement in the mode of preparing calomel, 

 is a ftriking example of fuch falutary corrections being fuc- 

 cefsfully introduced. 

 The method of A few obfervations upon the formula according to which 

 preparing j} r ^ j ames ' s powder, or the Pulvis Antimonialis, is prepared, 



James's powder, , r F , ' & ' .„ , .. . ~ x . 



or Pulvis And- anc ^ "P°n fome properties ot antimony, will place this ailertion 



mcnialis. j[ n a more prominent point of view. 



In order to prepare this powder, we are told to take equal 

 weights of bone or hartfhorn fhavings and crude antimony, 

 and calcine them together, at a high temperature : in other 

 words, to take phofphate of lime, which already contains a 

 great excefs of lime, and add to it an oxide of antimony. In 



• Philof. Tranf. 1801. 



this 



