[ *43 ] 
cold : they concluded from this, that all fuch various 
degrees of heat in thefe waters were owing either to 
the different degree of fubterranean fire, which they 
had undergone ; or elfe to the great didance, which 
fome of them had run in the earth, after they had 
been fufiiciently heated. They therefore maintained, 
that thole waters particularly termed acidulce (the 
greated part of which are impregnated with iron), 
or thole, which, tho’ intenfely cold, contained a 
large proportion of mineral matter, had in fome 
part of the earth been impregnated with it, by means 
of an intenfe heat, which they had been gradually 
deprived of by a long paffage thro’ the colder parts 
of the earth. 
Some naturaliffs again, of a later date, having ex- 
ploded the former notion as chimerical, have thought, 
that a vapour riling from vitriolic minerals, and 
mixed with the neighbouring dreams of water in 
the bowels of the earth, has imbued them with fome 
of the parts, and with the properties, of vitriol. 
Others are of opinion, that the exhalations of vi- 
triolic minerals, paffing thro' the cavities of the earth, 
are there condenfed by the fubterraneous cold into a 
limpid fluid, containing the very fined parts of that 
mineral fait : which duid, mixing with the praeter- 
labent dreams of water, and i filling out of the earth 
with them, produce thofe mineral fprings called 
vitriolic. 
The lad opinion I diall mention on this fubjedt, 
and which indeed appears the mod plaufible, is of 
thofe, who think, that the iron is corroded and dif- 
folved in thefe waters by means of an acid : for, as 
they imagine fimple water incapable of doing this, 
7 they 
