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cremor, which appears on an infufion of iron •, the 
reafon of which feems to be the lofs of the fulphure- 
ous parts of the chalybeat minerals by avolation, 
during the operations of the fire, which they under- 
go in refining. 
It appears from the fifteenth experiment, that the 
water of thefe two fprings contains a very differ- 
ent proportion of this cremor : and from the laid, 
that it is precipitated along with the ochrous parts, 
which happens upon the affufion of thefe alkaline 
liquors. 
The next trials were in quefd of alum. 
Exp. 17. A quantity of the water being kept for 
fome time in a boiling heat, and after it was cool 
being filtred quite clear from its ochrous matter, it 
fbill retained a fubacid and aluminous tafde in a very 
ftrong degree. 
18. To an ounce of common fpring-water there 
was added two gutts of freih fweet milk. This 
mixture being fhaken, the milk mixed intimately 
with the water, without any kind of coagulation. 
19. The fame experiment being made with the 
mineral water, the milk, upon its affufion, was fo 
curdled, or feparated into clouds, that the greatefd 
fhaking could not mix or incorporate it with the 
water. 
20. This experiment being alio made with a weak 
folution of alum in fpring-water, its effedds upon the 
milk were not in the leafd different from thofe of the 
mineral water. 
2 1 . And the fame trial being again repeated with 
. S 1' the 
