3 6 o Dr . Pearson’s Experiments and Obfervations 
clofe veffel, the mixture melted partially into a greyiflv 
mafs. 
<{d) 150 grains of the calcined antimony (J?) of this experi- 
ment were mixed with an equal weight of calcined hart’s horn. 
This mixture was raked about in an earthen difh for an hour, 
during a great part of which time it was red hot. On cooling, 
the powder was evidently lighter coloured than before this cal- 
cination. It was then expofed in a clofe crucible to a white 
heat for half an hour ; and, after cooling, a loofely cohering 
white folid, with a vitreous yellow coat, was found, little 
inferior in whitenefs, and otherwife refembling James’s 
Powder. 
(e) 300 grains of the calcined antimony (£) of this experi- 
ment were raked about in an earthen difli for an hour, a great 
part of which time they were kept red hot. On cooling, the 
calx was found of the fame colour as before; and after ex- 
pofing it in a clofe crucible in the melting furnace to almoft a 
white heat for half an hour, it was obferved to have been 
melted into a yellowifh mafs. 
It feems at leaft very probable, from this experiment, that 
no degree or duration of fire, applied in open or clofe veffels to 
antimony alone , can produce a calx of the fame kind as that in 
James’s Powder: nor, perhaps, can fuch a powder be 
compofed by fire applied, in clofe veffels, to calx of anti- 
mony mixed with calcined bone; but if antimony duly 
calcined be mixed with calcined bone, and expofed to 
air, in a due degree of fire, for a fufficient length of time, 
and then a ftill greater degree of fire be applied to it in 
clofe veffels, fuch a compound may be formed as James’s Pow- 
der. This experiment alfo proves, that the fulphur in anti- 
mony is no ways neceffary to the formation of this compound. 
2 The 
