on the Compofitlon of James’s Powder . 35X 
prefent when I made thofe experiments on the Pulvis antimoni - 
alis, prepared by Mr. Griffin, of Apothecaries’ Hall, and James’s 
Powder.Having, in the prefence of thefe twoGentlemen*, broken 
the feal of a phial of James’s Powder, bought of F. New- 
bery, and taken out of it the quantity required for the expe- 
riments, the bottle was again fealed by Mr. Cavallo with 
his feal, as well as the phial from which was taken the Pulvis 
antimonialis . Should any experiments be pubiiftied, which 
eftablifh different condufions from thofe contained in this Pa- 
per, with refpect to the identity of thefe two powders, I (hall 
be happy to endeavour to afcertain the truth by experiments, on 
the remaining parcels of the two powders, in the prefence of 
competent judges. 
I (hall next relate the experiments made with the view of 
confirming or invalidating the condufions drawn from the 
above analyfis, with refped to the ingredients and proportions 
of them in James’s Powder; and by which 1 efpecially en- 
deavoured to make faeh antimonial calces as this fubftance 
Contains, by proceffes different from thofe above related. 
exp. 1. {a) Hart’s horn (havings, of fix different parcels, 
well dried, Separately calcined in the fame manner, and appa- 
rently to the fame degree as when calcined with antimony to 
make Lile’s Powder, afforded a light brown coarfe powder, 
with a few thin light black pieces, and loft from 43 to 48 per 
cent . of their weight. The niean Jofs of weight, of courfe, was 
45 f per cent . 
(f) This calcined bone (a), being pulverized, was expofed 
to a greater degree of fire, in clofe veflels, than that neceflary 
to render the calcined mixture of antimony and bone-afhes 
white. The lofs of weight by this fecond calcination or expo- 
fure to fire was from two to three per cent . ; and the a(hes 
*' Dr„ Clarke alfo was prefent at the beginning of thefe experiments. 
were 
