on the Compofition of James’s Powder . 345 
To know whether James’s Powder contained any fubftance 
that could be decompofed by mild fixed alkalies, the following 
experiments were made. 
Thefe experiments with fixed alkali feerned to be efpecially 
neceffary, becaufe phofphoric acid, lime, and antimonial calx, 
are ingredients in James’s Powder; and it was obvious to 
fufpeft, that this acid might be united with calx of antimony 
as well as with lime ; which phofphorated antimony would be 
.decompofed by alkalies, and yield phofphorated alkali. 
Experiments with fixed alkalies. 
100 grains of James’s Powder were boiled in fix ounces of 
water, with 50 grains of mild alkali of tartar, for three hours, 
and then the remaining liquid was filtered, and evaporated to 
drynefs ; but the matter left after evaporation was nothing but 
the alkali u fed in the experiment, with a little of the powder 
itfelf. 
The refult was the fame on making the experiment with 
iCryftallized mineral alkali inftead of alkali of tartar. 
Synthetic Experiments . 
ALTHOUGH the inability to prepare James’s Powder 
•would not prove the above conclufions, with refpedt to its com- 
pofition, to be erroneous ; the being able to compofe a fubftance 
Vol. LXXXI. Z z poffeffing 
