on the Compojiuon of James’s Powder . 
but all the parcels of James’s Powder had either a (hade of 
yellow or of ftone colour, and none were perfeftly white, or 
fo white as fome fpecimens of the Pelvis antimonialis . Some 
of the parcels of James’s Powder and of the Pulvis antimoni- 
alis tailed braffy ; and other fpecimens of both powders had no 
tafte. All of thefe powders were gritty. Moft of the parcels 
of the Pulvis antimonialis were a little fpecifically heavier than 
thofe of James’s Powder. The fpecific gravity of both pow- 
ders was increafed by expofing them to fuch a degree of fire as 
brought them into almofl a femi-vitrified (late; and, on the 
contrary, the fpecific gravity of the Pulvis antimonialis was 
lefs than it is in its ufual (late, when made in fuch a degree of 
fire that the mixture preferves the powdery form. 
The experiments with water on the Pulvis antimonialis pro- 
duced the fame kind of appearances, but more (lightly than 
thofe with James’s Powder; for the hot folution of the for- 
mer grew lefs milky on cooling than that of the latter, and 
on evaporation to drynefs lefs fediment was found of the folution 
of Pulvis antimonialis than after that of James’s Powder*. 
The experiments with acetous acid on the Pulvis antimoni- 
alis (hewed, that this menftruum diifolved fometimes a greater, 
and fometimes a fmaller proportion of it than of James’s pow- 
der ; and the diffolved matter was found to be antimonial calx,, 
phofphorated lime, and calx of iron, and no other fubftance. 
It has been already faid, that the proportion of foluble mat- 
ter in nitrous acid was the fame, or nearly fo 5 of the Pulvis 
antimonialis as that of James’s Powder; and this diiTolved 
matter was phofphoric acid, calcareous earth, with a little anti- 
monial calx, and a minute portion of calx of iron, as exactly 
% The. reafon.for this difference is aligned in another place. 
