C I 4 I ] 
But now, to fum up the evidence, which thefe 
experiments, taken all together, do afford, concern- 
ing the mineral ingredients of this Spaw; I think 
they determine, with fome degree of certainty, that 
it contains two different principles of iron, both of 
which are fixed. The one, which is the ochrous 
earth, is a true miner a ferri , and, altho’ it be a crude 
mineral, exifts in the water in a very fine and fubtile 
form ; the other, which is the cremor or pellicle, 
whofe parts are alio extremely attenuated in the wa- 
ter, appears to be iron, not in its mineral, but in its 
metalline form, and, when thrown up upon the fur- 
face of the water, fhews itfelf like an extreme thin 
lamina of that metal. There feems alfo to be fome 
fmall proportion of fulphur joined with the metalline 
cremor. The other mineral ingredient, which enters 
into the compofition of this Spaw, is a confiderable 
proportion of an aluminous fait, which is conjoined 
with a fmall quantity of a light brown-coloured 
earth (probably a part of the matrix whence the fait 
is formed), and ftill more intimately connected with 
fome of the chalybeat parts of the water, which are 
not feparable from it either by elixation or evapora- 
tion. Whether thefe be faline or terreftrial, I can- 
not determine. 
Having thus endeavoured to difcover, by fome 
plain and fimple experiments, the mineral principles, 
with which this medicinal water is impregnated ; I 
fhall now only add fome observations, with refpedt 
to the origin of ffeel waters, and particularly of this 
Spaw, whofe origin, I think, is thereby difcovered' 
and afcertained in a very obvious manner. 
