A 
SS* 
and fo 
an in 
cold 
infufion. 
Th 
with a chalybeate more fuddenly than the frefh 
nfufi 
however, contains at 
aft 
xtractive matter, but more in a ftate of fol 
jate becomes dark* 
nt. When they i 
d 
as much 
Handing with the chalyb 
coction becomes more fa 
while that of the de 
of 
add 
of 
a certain age, the 
a 
halybeate renders them green; and when this is the 
cafe, they are found to be in a ftate of fermentat 
and effete 
Mild or cauftic alkalies 
lime, precipitate the extractive matter 
which in the cafe of the cauftic alkali is re-diflblved by a farther ad 
dition of the alkali. Lime-water precipitates lefs from a frefh infufion 
than from a frefh decoction ; and in the precipitate of this laft, fome 
mild earth is perceptible. The infufion is by age reduced to the 
fame ftate with the frefh decoction, and then they depofit nearly an 
equal quantity of mild earth and extractive matter ; fo that lime- 
water as 
well 
as 
chalyb 
may be ufed as a teft of the relative 
ftrength and perifhable nature of the different preparations, and of 
different barks. Accordingly, cold infufions are found by experi- 
ments to be lefs perifhable than decoctions ; infufions and decoctions 
of the red bark, than thofe of the pale: thofe of the red bark, how- 
ever, are found by length of time to feparate more mild earth with 
the lime-water, and more extracted matter. Lime-water as 
preci 
pitating the extracted matter appears an equally improper and dis- 
agreeable menftruum. Water has been found to fufpend the refin 
by means of much lefs gum than has been fuppofed. Rectified 
fpirit of wine extracts a bitternefs, but no aftringency, from 
fiduum of twenty affufions of cold water ; and water extracts aftrin- 
gency, bujt no bitternefs, from the refiduum of as many affufions ot 
rectifie 
pint 
The refidua of both are infipid 
From many ing 
experiments made on the Peruvian Bark 
'■ 
Dr. Irving, publifhed in a Differtauon which gained the prize 
medal given by the Harveian Society of Edinburgh in 1783, the 
power of different menftrua upon Peruvian Bark, is afcertained with 
greater accuracy than had before been done: and it appears, that 
efpect to comparative power, the following fluids act in the 
/ 
* Ed. New Difpenf. p. 25 1 
orde* 
