3oS Dr. Marcet’s Analysis of the Waters of 
oxalat of lime, consisted in driving off the oxalic acid by a 
low-red heat, and adding to the calcareous residue, then con- 
verted into a subcarbonat, a known quantity of muriatic acid 
more than sufficient to dissolve the whole lime. A piece of 
marble of known weight was afterwards added to take up the 
excess of acid, and from these data the quantity of lime was 
calculated with great precision. 
8. The clear solution containing nitrat of magnesia, nitrat 
of soda, and a small excess both of oxalat and muriat of am- 
monia, and amounting in bulk to about 4 ounces, was exposed 
to the heat of a lamp for concentration ; but in a few minutes 
the mixture became turbid and began tokieposite a white pow r - 
der, which, from former observations, I supposed to be oxalat 
of magnesia. To this solution concentrated to between 2 and 
3 ounces, and still warm, I added carbonat of ammonia with 
excess of pure ammonia. A considerable precipitation imme- 
diately appeared, and the mixture became opaque and milky. 
The next morning, however, the fluid had become quite trans- 
parent, and instead of a white impalpable precipitate, I found 
clusters of perfectly pellucid crystals spread over the bottom 
of the vessel, with distinct interstices between them. 
This salt was no doubt an ammoniaco-magnesian carbonate ; 
and the remaining solution, although still containing, as will 
presently appear, a vestige of magnesia, was so far free from 
it, as not to have its transparency disturbed by caustic potash. 
These crystals, after being well washed in distilled water, were 
exposed to a gentle heat to drive off the ammonia, in conse- 
quence of which they crumbled down into a white impalpable 
powder, exactly resembling common carbonat of magnesia. 
This powder being then treated, and its quantity estimated, in 
