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accuracy, from which I might have expedled to reap 
more fuccefs, as it is perhaps one of the moft confe- 
quence, that can be performed on this mineral water, 
as it is capable of demonflrating the existence of a 
fubllantial vitriolum Martis in it ; which is more 
than has been hitherto done, or perhaps ever will be 
done, concerning any one of the vaft number of 
chalybeat waters, which have been yet difcovered. 
When galls are added to the water, at the fame 
time with oil of tartar, inftead of its deep blue co- 
lour, it affords only a red tindture. 
It appears from the nth experiment, that an ad- 
dition of common water caufes the mineral water to 
precipitate its ochre ; and the reafon of this is ob- 
vious : for if tliefe ochrous parts be altogether terrene, 
as they appear to be, and exifl in the water uncon- 
nected with any other principle, then it inuft hap- 
pen, that as thefe parts are uniformly diffufed thro’ 
the water, in which they are lufpended as in a men* 
ftruum ; by the addition of common water, this 
menftruum being diluted, the cohefion of thefe ter- 
rene parts muff be thereby weakened, and their con- 
tact deftroyed ; lb that their menflrual equilibrium 
being thus taken off, they can be no longer fupported 
in the fluid, but mufh be precipitated by the force of 
their own gravity. 
Exp. i a. When the water was expofed for fome 
days to the air, there was a cremor l'eparated from 
it of a fhining chalybeat colour. This, like other 
kinds of cremor, takes a confiderable time to com- 
pleat its intire feparation from the fluid, out of which 
it is expelled : for when it was defpumated, a new 
cremor 
