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XVII. Obfervaltons and Fjxperiments upnn Dr. .Tamks's 

 Poivder, with a Method of preparing, in the humid IVay., 

 a Jimilar ^uhftance. By Richard Chenevix, E/q. 

 F.R.S. M.R.J. A.* 



A, 



.FTEIl the obfervations and experiments made by Doftor 

 Pearfon, to Inveftigate the nature of Doftor James's powder, 

 and prefented by him to this focielv, very httle remained to 

 be effefted or defired towards a further knowledge of the fub- 

 jeft. But thofe very experiments ferved to fugged, that the 

 mode of preparation was far from being the beft that the pre- 

 fent improved ftate of chemical knowledge might afford ; and 

 that, in all probability, a lefs dtfeftive compofition might 

 refuit from a procefs more conformable to fome improve- 

 ments, which of late have been advantageonfly applied to 

 pharmaceutic cliemiliry. 



It may be laid down as a genera! principle, that, in deli- 

 cate experiments, whether analytical or fynthelical, fire (that 

 potent and once believed to be univerfal agent) is too preca- 

 rious in its means, and too uncertain in its application, to be 

 employed with full and conllant fuccefs. And, if it is ftill 

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

 antieni cullom, are the principal reafons. But, where other 

 inethods can be devifed to effeft the fame combinations, (and 

 the humid way oflers many,) every perfon converfant in che- 

 mical knowledge will allow the benefit of adopting them. 

 The recent improvement in the mode of preparing calomel, 

 is a ftriking example of fuch falutary correftions being fuc- 

 cefsfully introduced. 



A few obfervations upon the formula according to which 

 Dr. James's powder, or the pulvis antimonialis, is prepared, 

 and upon fome properties of antimony, will place this afl'ertion 

 in a more prominent point of view. 



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

 weiohts of bone or hartihorn (havings 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 

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

 of the bone or hartfhorn will faturate, not only the liiine 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, 



• From the Pbitofo^hical "TranjMions for 1891. 



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