[ J 35 ] 
29. As I was accidentally deprived of the oppor- 
tunity of obtaining the cryftals of this fait, which 
would have been the bed. means of knowing to what 
fpecies it was to be referred 5 I dilfolved the whole 
mafs in a fmall quantity of fpring-water, and, by 
filtrating this folution, I obtained a large proportion 
of fine earth of a brown colour. 
30. This folution of the fait afforded a deep blue 
tindture with galls. 
31. The fame folution, being mixed with fyrup 
of violets, became of a reddifh colour. 
32. Saccharum Saturni being added to the folu- 
tion, precipitated a thick ladtefcent cloud. 
33. Ol. tart. p. d. being alfo added to this folution, 
it caufed no vifible effervefcence, yet raifed fome 
bubbles of air, and caufed a coagulation of many 
fmall brown terrene nubeculas in the water ; which, 
after handing fome time, fubfided to the bottom, and 
left the water clear. 
Thefe experiments do plainly evince, that this 
water contains an aluminous fait, conjoined with a 
fine terrene fubftance, which is probably a part of the 
matrix, from whence the fait has been formed. 
This fait gives no fi gns of any alkaline principle ; 
but, on the contrary, of an acidity, as its folution 
reddens with fyrup of violets. 
With this fait there are alfo intimately conjoined 
fome very fubtile chalybeat parts, which' are not fe- 
parable from it by elixation or evaporation. 
Alum is diftinguifhable from all other mineral 
falts, by liquifying and bubbling upon a red-hot iron, 
and turning into a white calx. But this could not 
be well expedted from this aluminous fait, which we 
7 had 
