[ J 3 6 ] 
had extracted from the water, becaufe it was ex- 
tremely foul, by being combined with fo large a 
proportion of earth ; which earthy parts were the 
occafion of turning the fait of a blackifh colour upon 
the iron. However, we fee it turns white by a fur- 
ther degree of heat. But if the fait had been dif- 
folved, filtrated, and cryftallized, till it had been pu- 
rified and freed from this terrene matter, it would 
then certainly have had the fame appearance upon 
the red-hot iron, as a pure aluminous fait. Again, 
as it is peculiar to an aluminous fait to liquify in 
fome degree with fire, fo we fee, that this was evi- 
dently the cafe of this fait. Its eliquation indeed 
could not be fo remarkable, as in pure alum, be- 
caufe of its being mixed with fo much earth but 
that it did liquifv in fome degree is plain, becaufe 
the whole mafs of fait and earth, even when reduced 
to a powder, ran all together like a cinder. 
The experiment upon the folution of this fait with 
ol. tart. p. d. is alfo a further proof of what we have 
already aiferted : for tho’ there was no vifible effer- 
vefcence, yet the bubbles of air fhew, that there was 
an inteftine conflict of the oil with the acid principle 
in the folution j which being abforbed by the alkali, 
the earth was precipitated, to which it formerly ad- 
hered. 
The two next experiments were made in order to 
diicover, whether an acid or alkaline principle pre- 
vailed in the water. 
Exp. 34. Forty gutts of the fyrup of violets being 
added to an ounce of the water, the mixture became 
of a bright fea-green colour. 
35- A 
I 
