[ 2l8 ] 
XXVI. An Experimental E7jquiry mto the 
hlmeral Elaflic Spirit^ or Air^ contained 
in Spa Water ; as well as into the Mephitic 
finalities of this Spirit, By William 
Brown rigg, M, D. F. R. S, 
jRead June T is now twcnty-four years fince I 
A prefented to the Royal Society feveral 
Eflliys on Damps, which were read at the meetings, 
and are preferved among the' papers of that moft 
learned body. Thofe effays contained a few of the 
obfervations and experiments which I had colledted, 
for a larger work, on that fubjed: ; and for which, as 
opportunity offered, I have fince col levied materials. 
And being defirous that fome of my obfervations 
fliould be further verified, and more fully afcertained 
before they were made public, I therefore declined 
the honour of having thofe eflays publifiied among 
the Tranfadtions of the Royal Society j efteeming it 
fufficient, at that time, to have excited feveral of my 
friends, and among thefe, Sir Hans Sloane, and the 
Rev, Do(ffor Hales, to communicate to me their fen- 
timents on this fubjedf. 
In one of thofe effays I had occafion to remark, 
that a more intimate acquaintance with Damps 
and other mineral Exhalations might lead to a 
“ difcovery of the nature and origin of thofe fubtile 
“ and volatile principles, which enter the compofition 
“ of various mineral waters, and are ffifed their fpi- 
“ lit; 
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