116 Dr Daubeny on separating Lime from Magnesia. 
concentrated by evaporation, until it measured only 1^ oz. when 
a slight appearance of a precipitate commenced. Being further 
diminished to 1;^ oz. the precipitate collected seemed to corre- 
spond pretty nearly to what might have been expected, had the 
solution consisted merely of sulphate of lime. 
This experiment not being quite conclusive, I adopted the 
more direct method of ascertaining the quantity of sulphate of 
lime which would be dissolved by equal measures of pure water, 
and of a solution of the magnesian sulphate. I therefore took 
two portions of dry sulphate of lime, each weighing 5 grains, 
and poured upon the one 3^ oz. of pure water, and on the other 
the same quantity of a weak solution of sulphate of magnesia in 
the -same fluid. Both liquors being after some time decanted 
off, the residuum from each was carefully washed with a quan- 
tity of water, as nearly as possible equal, and dried under pre- 
cisely similar circumstances, when that which had been treated 
with distilled water only, was found to weigh 3.35 gr. ; whilst 
the other was reduced by the saline solution to 3.16. 
In order to confirm these results, I added oxalate of ammo- 
nia to the solution in which no sulphate of magnesia was present, 
and obtained from it a portion of oxalate of lime, which, when 
converted into a carbonate by heat, amounted to 1.42, equiva- 
lent to 1.92 of dry sulphate of lime. This, indeed, is 0.27 more 
than we should infer from the former experiment, owing, pro- 
bably, to the oxalate of lime being but imperfectly converted 
into a carbonate. The two experiments, however, serve in the 
main to confirm each other. 
The same pi*ocess was then repeated with the calcareo-mag- 
nesian solution, but with this difference in the result, that the 
oxalate of ammonia produced at first no change whatever, and 
that afterwards, when the precipitate was collected, and had 
been exposed to a similar degree of heat, the amount of the sul- 
phate of lime dissolved, appeared to have been only 1.225, less 
by 0.7 gr. than the quantity collected in the last experiment, 
and by 0.5 gr. than what would have been inferred from the 
loss sustained by the sulphate of lime, on which it was poured. 
I should therefore have suspected some inaccuracy, had it 
not been for some analogous facts hereafter to be mentioned, 
which are such as lead me to infer, that the predominance of 
