304} Dr Daubeny on separating Lime from Magnesia* 
These circumstances may serve to explain the loss experienced 
in those cases where the earth was employed unmixed ; but the 
fact, that whenever the same substance was made use of in con- 
junction with lime, my precipitate fell short of that obtained 
when the magnesian salt was employed alone, tends to confirm 
the inference deduced from the foregoing experiments, viz. That 
a portion of magnesia is thrown down by carbonate of ammonia, 
when lime happens to be present. 
This was further proved by the following experiments, framed 
under the idea of obviating the uncertainty which the variable 
composition of the carbonate of magnesia was calculated to pro- 
duce. 
One ounce of muriate of lime, which had previously been found 
to contain 11.4 grains of base, was mixed with an equal quan- 
tity of a solution of muriate of magnesia, which, from the pre- 
cipitate afforded by phosphate of soda, appeared to contain 5.76 
grains of earth. Of these 11.4 grains of lime, carbonate of am- 
monia threw down 10.8, when no magnesia was present ; but 
the same re-agent added to the mixed solutions, gave a preci- 
pitate which indicated no more than 10.2, taking the mean of 
three experiments. 
Yet, although the addition of oxalate of ammonia clearly 
proved that lime was present in the supernatant liquor, it ap- 
peared, on the other hand, that a portion of magnesia had been 
precipitated ; for the powder being redissolved in an acid, and 
treated as before, gave evident marks of the presence of the 
latter earth. 
I also found, that the quantity of magnesia, indicated by the 
precipitate, which phosphate of soda afforded was less by 0.2 gr. 
than when no lime had been present, taking the mean of two re- 
sults, which did not differ more than 0.03 from each other. 
The residual fluid, after it had experienced the full effect of 
both these re-agents, was evaporated to dryness, and redissolved 
in an acid; but after carbonate of ammonia had ceased to throw 
down lime, no indications of magnesia appeared on the addition 
of the alkaline phosphate. 
It would seem, then, that when carbonate of ammonia is 
added to a mixed solution of two salts, the one containing lime, 
the other magnesia, a small proportioil of the latter earth is 
