( 6i6 ) 
The hot Mineral waters may contraft fome alteration from the 
ful phureotis and bituniinousniatters,which they raect with in their 
Goiirfe ; for thcfe matters partake of certain fubtilfalts, which 
thofe waters may refolve and carry away with them. 
Some Cold or Tepid mineral waters have a (harpilh or vinous 
tafte, which is not obferved in any of thofe that are confidcrably 
hot: But this tafte is foeafie loft upon the leaft beat, and even in 
the free Air , that 'tis hard to know what it is that produces it. 
It is not only found in waters that are efteem'd to be Aluminous 
and Vitriolate, but a!fo in thofe that are manifeftly Nitrous , and 
which abound in Sulphureous Salt oppofit to Acids. 
The Caufes of the Heat of fome Mineral waters are little known. 
There is reafon codoubt,whether there be Subterraneous fires ca- 
pable to heat them ; or whether they have received this heat by 
Che exhalations of fome Mineral juyces that are fermentable,or in 
which f jme effervefcence is made by the mixture of other juyces. 
All thefe difficulties have retarded the publication of thefe 
Obfervations, which,it feems, this Koyd jicAdemy hath been thefe 
four Years a making upon the waters , that have been fent them 
from divers Provinces of Sun^e , and that have undergone their 
examenas occafion hath ferv'd for it. 
Having premifed thefe particulars, to manifeft the Difficulty 
and nicety of this kind of refearch; they fubjoy n the Method em- 
ploy 'd in this examination; which indeed is made with that confi- 
deration that becomes the wifdomand care of that Illuftrious Bo- 
dy, and is adapted to lead them into a greater Jcnowledgof thofe 
waters,than thofe Authors had that have hitherto written of them, 
and that very often have not judged of them but by the effefis, 
which might be referr'd to divers eaufts. 
Now, according to this Examen made upon a great number of 
waters from different Springs, both hot and cold,they have parti- 
cularly obferv'd Salts and Earibs of divers qualities , and in dif- 
ferent quantities. 
The SaltSj which condenftd after diftillation, or a flow evapo- 
ration of the waters, were brought before them, arc here reduced 
to two forts; viz. The cf^e is the Nitre of the Antients, w* they 
defcribeto beafulphureous mineral Salt. , like to the Jlcali of 
Plants ; the oth^r^ the Common Salt eonfider*d in either of its dif- 
ferent portions , or according to the commixture of both toge- 
ther; And 'tis remarkable, me thinks,that in none of thofe waters 
there 
