Sie Ct Tt Ge N V. 
f 
Of the Quantity of mere Alkali in diferent Alkaline Subfiances as 
exhibited by the aluminous Teft. 
CRYSTALLIZED SODA. 
I BEGIN. with this as being the pureft mineral alkaline fub- 
ffance in a dry form produced by art. Though it contains 
only » of its weight of real alkali, the remainder being water and 
fixed air, but the proportion of alkali being invariably the fame, 
it is the fitteft for a ftandard with which other fubftances con- 
taining the fame fort of alkali may be compared. I found that 
as much of this fubftance as would contain 480 grains of mere 
alkali would precipitate 725 grains of earth of allum dried and 
treated as already mentioned, and confequently that 480 grains 
of mere mineral alkali precipitate 725 of earth of allum. 
Noré, That in this and all the fubfequent experiments a little 
more earth of allum is precipitated than is mentioned, becaufe 
a little always remains in the filtering paper that cannot be had 
out of it, and I have reafon to think by weighing the paper 
before and after, that this quantity amounts to 3 or 4 grains; but 
as this defect is the fame in all cafes, it does not invalidate the 
comparifon. 
Dz SWEET 
