m the Cotnpojttion of James’s Powder . 359, 
a fhowy whitenefs. This yellow coat is one reafon for the 
powder being of a fliade of yellow in fome fpecimens. 
Suppofing the fufibility of the antimonial calces to be dimi- 
nifhed the more they are calcined ; the following experiment 
(hews* that the antimonial calx in James’s Powder is more 
calcined than that in Exp. 2. 
exp. vii. yoi grains of calcined antimony, as prepared in 
Exp. 2. triturated with 53$ grains of calcined bone, formed a 
powder of a bluifh caft, which being expofed in a clofe cru- 
cible, for half an hour, in a melting furnace, the degree of 
fire in which was 120° of Wedgwood’s fcale, it was found 
melted into a vitreous, pale bluifh mafs ; and the infide of the 
crucible was glazed yellow* with red ftreaks, and had argen- 
tine fpicula adhering to it* 
exp. viii. 800 grains of the calcined antimony of 
Exp. 2. were calcined for eight hours in a di(h, as in 
making Lile’s Powder, by ftirring it conftantly, and keeping 
the bottom of the vefiel red hot during the whole time ; the 
two laft hours alfo the whole of the powder was kept red hot* 
On cooling, this calx was an impalpable light-brown powder. 
(a) 100 grains of this calx, triturated with an equal quan- 
tity of calcined hart’s horn, formed a powder very unlike 
James’s Powder, for it was of a light-brown colour. On expo- 
fing it to about 1 20° of fire it melted into a yellow opaque mafs. 
( [b ) The remaining 700 grains of the calcined antimony of 
this experiment were expofed to fire and 1 air. as before for eight 
hours longer, and kept red hot a great part of the time ; but 
the calx became very little lighter coloured than before. 
( c ) 100 grains of this calx laft mentioned (£), triturated 
with as much calcined hart’s horn, being expofed to the degree 
®£ fire ufually applied in making the Pulvis Antimonialisy in 
6 clofe 
