[ 2 53 ] 
AN APPENDIX, 
Containing an account of fome experiments 
made by Mr. Hey, which prove that there 
is no oil of vitriol in water impregnated 
with fixed air extracted from chalk by oil 
of vitriol ; and alfio a letter from Mr. Hey, to 
Dr. Prieftley, concerning the effects of 
fixed air. applied by way of clyfter. 
Experiments to prove that there is no 
OIL OF VITRIOL IN WATER IMPREGNATED 
WITH FIXED Air. 
It having been fuggefted, that air ariftng from 
a fermenting mixture of chalk and oil of vitriol 
might carry up with it a fmall portion of the 
vitriolic acid, rendered volatile by the aft of fer- 
mentation ; I made the following experiments, in 
order to difcover whether the acidulous tafte, 
which water impregnated with fuch air affords, 
was owing to the prefence of any acid;, or only to 
the fixed air it had abforbed. 
Experiment I. 
I mixed a tea-fpoonful of fyrup of violets with 
an ounce of diftilled w T ater, faturated with fixed 
air procured from chalk by means of the vitriolic 
acid; but neither upon the fir ft mixture, nor after 
% {landing 
