[ 23 ° ] 
it is hardly pofliblc to make it, according to the pro- 
cefs of the London difpenfatory, without giving it 
fome degree of empyreuma. The extradl employed 
in my experiment was prepared by a very diligent 
and caretul apothecary - } yet a confiderable portion of 
it prefently fubfided in a powdery form to the bottom 
of the glafs, which on examination appeared to be 
the burnt parts of the Bark. How little then is this 
officinal pieparation to be depended upon, when we 
confider the careleffinefs and inaccuracy of the gene- 
rality of apothecaries ! 
It is the practice of the mod: eminent phyficians, 
to join acids with the Bark, in the cure of putrid 
difeafes ; and Sir John Pringle has oblerved, that in 
bilious fevers the cortex anfwered bed in rhenifti wine, 
after danding a night in infufion a . This fuggeded 
to me the Vlllth Experiment and I flattered myfelf, 
that by macerating the Bark in a mixture of vinegar 
and water, thefe two antifeptic medicines would be 
more accurately combined together ; and that perhaps 
the acid might promote the diflolving power of the 
aqueous mendruum. In the latter expectation it 
appears that I was difappointed ; and whether the 
former was better grounded, mud be left to abler 
judges to determine. The refult of this Experiment 
was fo contrary to my expectations, that I determined 
to make further trials of the effeCts of vinegar in 
dedroying that property, in certain vegetable fub- 
itances, by which they flrike a black colour with cha- 
lybeates, which has been long regarded as an almod 
indubitable ted of adringency. 
* Difeafes of the Army, Edit. iv. p. 213. 
An 
