125 
the Water of Kilburn Wells. 
with it, and the magnesia thus separated weighed, when washed 
and dried, 170 grains : this having been again saturated with 
diluted vitriolic acid, afforded 910 grains of pure crystallized 
vitriolated magnesia. The solution remaining after the sepa- 
ration of the magnesia having been duly evaporated, yielded 
282 grains of crystallized Glauber salts, exclusive of what 
had been formed by the above-mentioned admixture of the 
natron. 
EXPERIMENT IV. 
The 188 grains of remaining earth, mentioned in the pre- 
ceding experiment, were put into aqua regia, and the solution 
mentioned in the first experiment, as marked (A), was added. 
This mixture having been well heated, and again suffered to 
cool, was put on some filtering paper ; and what remained 
on this, having been well washed with diluted spirit of wine, 
and dried, weighed 112 grains. 
The filtered solution was then gently evaporated, during 
which it deposited six grains of selenite ; a sufficiency of phlo- 
gisticated alkali was now added, to separate the iron ; 25 grains 
were required, and the dried blue precipitate weighed 15 
grains. (It is to be observed, that the phlogisticated alkali con- 
tained, in 25 grains, 4^ grains of the calx of iron.) 
The above blue precipitate was put into a small crucible, 
and kept for a proper time in a red heat, when it left 7^ grains 
of calx of iron, which was attracted by the magnet ; if 
from this be deducted the 4^ grains contained in the alkali, 
there will remain three grains which had been contained in 
the water. 
