254 ORD. XIV. Contorte. CINCHONA OFFICINALIS: 
~ addition of a chalybeate renders them green ;- and when this is the 
ease, they are found to be in a state of fermentation, and effete, 
Mild or caustic alkalies, or lime, precipitate the extractive matter, 
which in the case of the caustic alkali is re-dissolved by a farther 
addition of the alkali. Lime-water precipitates less from a fresh 
infusion than from a fresh decoction; and in the precipitate of this 
last, some mild earth is perceptible. The infusion is by age re- 
duced to the same state with the fresh decoeticn, and then they 
deposit nearly an equal quantity of mild earth and extractive mat- 
ter; so that lime-water as well as chalybeate, may. be used as a 
test of the relative strength and perishable ‘nature.of the different 
preparations, and of different barks. Accordingly, cold in fiisions: 
are found by experiments to be less perishabie than decoctions;— 
infusions nad decoctions. of the red bark, than those of the pale: 
those ef the red: bark, however, are found by length of time to 
separate more mild earth with the lime-water, and more extracted 
matter. Lime-water as precipitating the extracted matter appears 
an equally improper and disagreeable menstruum. Water has. 
been found to suspend the resin by means of much less gum than 
_has been supposed. Rectified spirit of wine extracts a bitterness, 
but no astringency, from a residuum of twenty affusions of cold 
water; and water extracts astringency, but no bitterness, from the 
residuum of as many affusions of rectified spirit. The residua of 
both are insipid.’’* 
From many ingenious experiments madg on the Peruvian Bark 
by Dr. Irving, published in a Dissertation which gained the prize- 
medal given by the Harveian Society of Edinburgh in 1783, the 
power of different menstrua upon Peruvian Bark, is ascertained. 
with greater accuracy than had before been done: and it appears, 
that with respect to comparative power, the following fluids act in 
the order in which they are placed: Dulcified spirit of vitriol : 
Caustic ley: French brandy: Rhenish wine: Soft water: Vinegar 
and water: Dulcified spirit of nitre: Mild volatile alkali: Rectified 
* Ed. New Dispens. p. 251.. 
