[ 240 ] 
therefore, exatflly to refemble each other both In- 
their nature and origin. And of this opinion is the 
above-cited Fred. HorFman, who feems in every 
refpedl qualified to have advanced the knowledge of 
mineral waters to its higheft perfedion, had he been 
furnifhed with a more accurate hiftory of mineral 
exhalations.. By means of fuch an hiftory, he would 
probably have been enabled to diftinguifli the fpii its 
of mineral fountains into their different kinds, which 
he now feems to confound together, as if they were 
alike in every refped. Altho’ ’tis not improbable, 
that as there is a great variety of fubterraneal exha- 
lations, fo alfo there may be various kinds of mineral 
fpirits ; and that water may be capable of imbibing 
levcral kinds of thofe exhalations which it meets 
with in the bowels of the earth. The Rev. Dodor 
Hales, in his Statical Elfays, and Dodor Shaw, in 
his Inquiries into the Nature of the Scarborough Wa- 
ters, have lliewn various ways whereby thefe aerial 
fpirits may be extraded. If, therefore, the fpirits 
extraded from different mineral waters, by the ways 
which they dired, were carefully examined, and 
were compared with each other, and with the differ- 
ent forts of mineral exhalations which are found in 
the earth, we might, perhaps, more eafily diftinguifli 
their feveral kinds, and more exadly difcover their 
refemblance to the feveral forts of mineral exhalations, 
than by any other method which could be put in 
pradice. 
But, without having recourfe to experiments of 
this kind, we may from other oblervations conclude, 
that the fpirit of thofe waters which are called Aci- 
dulae is nearly related to the choak-damp, or ftith, 
found 
