C 97 3 
in my experiments and thofe of the gentlemen juft 
mentioned. 
Experiment III. 
Two drams of a tindure obtained from one ounce 
of powdered Peruvian bark, with four ounces of 
redified fpirit, and filtered without preflure, gave two 
grains of refinous matter ; but the fame, when the 
filtration was finifhed, with preftiire on the top, gave 
fix grains of the fame fubftance. 
Ob. It may therefore feem advifable to ufe preflure 
always in filtering this tindure; and perhaps all the 
other tindures would be rendered ftronger by the fame 
means. 
Experiment IV. 
Two drams of the powder of the external lamina 
of the bark, digefted in the cold with redified fpirit 
of wine, afforded two grains of refinous matter. 
Experiment V. 
Two drams of the internal lamina, treated as above, 
gave a grain and half of refinous matter. 
Ob. Though this fingle trial cannot determine 
the comparative quantity of refinous matter in each 
lamina; yet it may fhew, that each of them contains 
it, which, as far as I know, has not yet been proved 
by experiment. 
Experiment VI. 
Two tindures were prepared from the fame quan- 
tities of the fame bark, and of the fame redified fpirit 
of wine; but the one was digefted two hours, in 
B. M. the other 24 hours in the cold: a dram of the 
former yielded three grains, and the fame quantity of 
the latter one grain of refinous fubftance. 
Vol. LVI. O 
Ob. 
