gxS Dr. Pearson’s Experiments and Obfervations 
fmooth, with fome rather rough particles, and it is gritty in 
the mouth. Moft parcels at firft are taftelefs ; but in about a 
minute there is a flight braffy tafte. It is perfe&ly inodorous. 
Specific gravity . 
This powder feels much heavier than any of the common 
earths and (tones in a pulverized ft ate. One of the phials, 
nearlv full, in which it is fold, reckoned to hold a quantity 
equal to twelve packets, or 480 grains, contained 470 grains 
troy weight of James’s powder. This phial, filled with dis- 
tilled water to the fame height that it had been by the powder, 
was found to contain nearly four drachm-meafures, or about 
240 grains, of this liquid 
Effe&s of fire. 
(<i) The exterior part of the flame of a candle applied, by 
means of the blow-pipe, to about one, two, and three grains 
of James’s Powder on charcoal, and alfo in the fpoon, only 
made it yellowifh while hot, but, on cooling, this colour difap- 
peared. The interior and hotteft part of the blue flame turned 
this powder yellow, and when continued fo as to ignite it, a 
white inodorous fume or vapour arofe, which loon ceafed ; 
and though the heat was continued, the powder neither ap- 
peared to diminifh nor melt; but, on cooling, a (lightly co- 
# After this Paper had been read, an experiment, in a different manner, was 
made to afcertain the fpecific gravity of this powder. The quantity which nearly 
filled a phial weighed 437 grains ; and filling the fame phial, to the fame height, 
with difiilled water, the temperature of which was 65°, the water weighed 250,2 
grains. The reafon of the variation in thefe refults, in making ufe of different 
parcels of this medicine, will be obvious, from the following account of its 
preparation, and the great difficulty of determining, with accuracy, the fpecific 
gravity of powders. 
0 hering 
