354 Dr. Pearson’s Experiments and ObJ'ervations 
be vague; yet it may be of fome application to obferve, that 
the proportion of antimonial calx, eftimated to be contained in 
Lile’s Powder or Pulvis antimonialis, and James’s Pow- 
der, p. 343. from the analyfis of them, does not differ more 
confiderably from the proportion of this calx than may, per- 
haps, be reafonably expected on calculation from thefe four lafl 
experiments to exift in them : for yof parts of antimonial 
calx, p. 352. to 5 4 i parts of bone-alhes, p. 351. is as about 
56,4 parts of this calx to 43,6 parts of calcined bone; and, 
on analyfis, James’s Powder afforded _ ! o ^ of antimonial 
calx, and of phofphorated lime, or nearly fo, p. 343. 
allowing for the wafle. 
exp. v. This experiment fhews the degree of fire neceflary to 
render the antimony calcined with bone of a white colour; 
and that this whitenefs does not depend on the air, but on the 
fire. 
0) 1 5°° grains of the calcined mixture of antimony and 
bone, Exp. 3. were kept red hot in a clofe veffel for 
half an hour. On cooling, I found the powder changed 
from a cineritious or clay colour to a whitifh colour with 
a (hade of yellow. The Tides of the crucible were not glazed. 
The pyrometer in the middle of the powder had contra&ed to 
40°. This powder was much inferior in whitenefs to James’s 
Powder, being much yellower.. 
( 6 ) Another parcel of the fame powder, Exp. 3. was 
expofed in the fame manner, but to a greater degree of fire, 
in which the crucible was almofl white hot for half an hour. 
Alter cooling, the powder, was found changed to a loofely 
cohering, fnow-white, heavy mafs, and the Tides of the cru- 
cible were covered with, a yellow glaze. This mafs, which. 
was 
