VOL. LXXXI.] PHILOSOPHICAL TRANSACTIONS. Ql 



be considered to be more decisive than the rest for establishing the identity, of 

 James's powder, and a powder formed by calcining together antimony and bone- 

 ashes. I therefore requested Mr. Cavallo and Mr. Turner to be present when I 

 made those experiments on the pulvis antimonialis, prepared by Mr. Griffin, of 

 Apothecaries' Hall, and James's powder. Having, in the presence of these 2 

 gentlemen,* broken the seal of a phial of James's powder, bought of F. New- 

 bery, and taken out of it the quantity required for the experiments, the bottle 

 was again sealed by Mr. Cavallo with his seal, as well as the phial from which 

 was taken the pulvis antimonialis. Should any experiments be published, which 

 establish different conclusions from those contained in this paper, with respect to 

 the identity of these 2 powders, I shall be happy to endeavour to ascertain the 

 truth by experiments, on the remaining parcels of the 2 powders, in the pre- 

 sence of competent judges. I shall next relate the experiments made with the 

 view of confirming or invalidating the conclusions drawn from the above analysis, 

 with respect to the ingredients and proportions of them in James's powder; and 

 by which I especially endeavoured to make such antimonial calces as this sub- 

 stance contains, by processes diff'erent from those above related. 



Exper. 1. (a) Hartshorn shavings, of 6 different parcels, well dried, sepa- 

 rately calcined in the same manner, and apparently to the same degree as when 

 calcined with antimony to make Lile's powder, afforded a light brown coarse 

 powder, with a few thin light black pieces, and lost from 43 to 48 per cent, of 

 their weight. The mean loss of weight of course was 45 j per cent. 



(b) This calcined bone (a), being pulverized^ was exposed to a greater degree 

 of fire, in close vessels, than that necessary to render the calcined mixture of 

 antimony and bone-ashes white. The loss of weight by this 2d calcination or 

 exposure to fire was from 2 to 3 per cent. ; and the ashes were as white as snow. 

 The total mean loss of weight, by these 2 calcinations, was then -^Vo- 



Exper. 2. 2000 grs. of coarsely powdered antimony were calcined in an 

 earthen dish, as in n)aking Lile's powder, by constantly raking them about for 

 above 3 hours. During a great part of this time the vessel was red-hot at the 

 bottom ; and for the last hour the sulphureous fumes had entirely ceased. The 

 calx thus produced was of a pale bluish colour; it melted, in a low degree of 

 heat, into an opaque, scoria-like brittle mass ; it yielded no hepatic air with ma- 

 rine acid ; it weighed 1400 grs. or the antimony lost nearly 29^ per cent. The 

 pyrometer in the vessel with the antimony during its calcination, was contracted 

 to the dth degree of Wedgwood's scale. The sum therefore of the loss of an- 

 timony and bone by calcination in this manner, separately, was 37i- per cent. 

 These 2 substances were in the next place calcined together in the same manner 

 in an open vessel, as above-mentioned. 



* Dr. Clarke also was present at the beginning of these experiments. — Orig. 



N 2 



