\ Dr Daubeny on separating Lime from Magnesia, Sll 
plete separation of the two earths, or for determining their re- 
lative proportions. 
Other methods for effecting the separation of the two earths 
have been suggested ; but the report made by Dr Thomson ^ 
and other able chemists, on their merits, is not very encouraging. 
One of these is to precipitate the lime by means of bicarbo- 
nate of' potass, which, it was presumed, would retain the whole 
of the magnesia in solution ; but this has been shewn by Bu- 
cholz not to be the case, — a portion of the lime being retained,, 
whilst a part of the magnesia is precipitated. 
Another, recommended by Professor Dobereiner of Jena, is 
to dissolve the magnesia, reduced to the state of a carbonate, in 
a solution of muriate of ammonia, thus separating it from the 
carbonate of lime, on which he represents this salt as having no 
action. 
I have shewn, however, in a preceding part of my paper, that 
this statement is not strictly correct, even when the carbonate of 
lime is unmixed, and Professor Pfaff of Kiel has proved, that 
the co-operating affinity of the magnesia causes a portion of the 
lime to be taken up, by the ammoniacal salt, whenever the two 
earths exist together. 
On these methods I have nothing further of my own to offer, 
and only notice them in order to complete this sketch ; but 
there are other schemes of analysis that have occurred to me, 
on which I have a few observations to make, before I conclude 
this part of the subject. 
One of' these is founded on the readiness with which magne- 
sia parts with its acid, under an increased temperature, an in-^ 
stance of which we have already met with, in the partial decom- 
position of 'sulphate of magnesia, upon exposure to a red heat. 
The muriate being still more readily affected by the same agent, 
I conceived that it might be possible to separate it from muriate 
of lime by this method, as the latter, when submitted per se to 
a red heat for some hours, appeared to lose none of its acid. X 
found, however, that even after several hours exposure to this 
temperature, the muriate of magnesia was but imperfectly de- 
composed, for the insoluble base which remained, when dissolv- 
ed in nitric acid, indicated by its colour the presence of muria- 
tic acid, and gave a precipitate with nitrate of silver. This pre- 
