3 1 S Dr Daubeny on separating Lime from Magnesia. 
cipitate was found to weigh 0.27, equivalent to 0.05 of muria- 
tic acid ; the insoluble residuum amounting to 5.8 grains of 
hydrate of magnesia. The 4.2 grains which were driven off, 
consisted partly of acid and partly of water ; but it is difficult 
to determine the relative proportions of each in this manner, be- 
cause muriate of magnesia cannot well be freed from water, 
without decomposing a part of its acid. I found, too, that 
when muriate of magnesia and muriate of lime were heated to- 
gether, the loss exceeded that which could have resulted from 
the same quantity of muriate of magnesia alone, and that this 
must be attributed to the decomposition of the calcareous salt, 
was evinced by the effect of oxalate of ammonia upon the preci- 
pitate, when dissolved in an acid. From some experiments 
which I made, it seemed probable that the increase amounted 
to about per cent. ; but the difficulty of procuring muriate 
of magnesia perfectly dry, without diminishing its solubility, by 
driving off the acid, induced me to vary the experiment in the 
following manner : I took 5 grains of carbonate of magnesia, 
dissolved it in muriatic acid, and having driven off the excess 
of acid, exposed the salt to a red heat for half-an-hour. The 
residuum being then treated with water, in order to separate the 
soluble from the insoluble portion, that which remained on the 
filter being dried was found to weigh 1.42, and what had been 
taken up by the water, of which nearly half a pint was employ- 
ed, 0i24 gr. Both these portions were found, however, to be 
submuriates ; for nitrate of silver gave a precipitate with both 
of them. In order to learn whether muriate of lime would un- 
dergo decomposition, when muriate of magnesia was present, I 
took 5 grains of a pure carbonate of lime, and having dissolved 
it in muriatic acid, obtained a salt, which, when dried by exposure 
to a red heat, weighed 5.2. I then dissolved 5 grains of the 
very same carbonate of lime in muriatic acid, with an equal 
quantity of the same carbonate of magnesia as that employed in 
the preceding experiment, and having driven off the excess of 
acid, exposed the mixed salt to the same degree of heat as that 
employed previously. Water being added to the residuum, 
left an insoluble powder, amounting not to 1.42, but to 1.73, 
and took up only 4.3 instead of 5.2 grains, which the preceding 
experiment proves woiJd have been the result, if the same por- 
tion of muriate of lime had been employed alone. 
