[ IOI ] 
Experiment XVI. 
Vitriolic acid dropped into the folution (Exp. 15.) 
precipitated its refin. 
Experiment XVII. 
Common water dropped into the folution (Exp. 15.) 
united with it uniformly. 
Experiment XVIII. 
Five grains of the refinous part were agitated with 
one ounce of water, and one grain was diflolved. 
Experiment XIX. 
Five grains of the refinous part, being rubbed with 
an equal quantity of frefh quick-lime, and agitated 
with an ounce of water, were all diflolved to one 
grain. 
Ob. The very ingenious difcovery of Mr. M c Bride, 
regarding the abftradion of fixable air in the folution 
of refinous bodies, fufficiently explains thefe ex- 
periments. 
Experiment XX. 
A dram of bark was infufed for 24 hours in an 
ounce and an half of fpirit of wine, then filtered, and 
the tindure decompofed with water, and again filter- 
ed, fo as to leave the refinous part in the filtre ; the 
gummy part which pafied the filtre, turned a folution 
of green vitriol, black. The refinous part was agitated 
with water, to purify it from any adhering gum; 
and what pafied the filtre a fecond time, gave a very 
light tinge of black to the folution of vitriol. 
Experiment XXI. 
The refin, obtained as above, was rubbed with quick- 
lime, and then diflolved in water, which folution, 
when 
