1^0 Dr Daubeny on separating Lime from Magnesia, 
ed. In the latter case, I find that the magnesian salt, in cer» 
tain proportions, almost entirely prevents the precipitation of 
hme from a solution of its sulphate, and in all cases appears to 
suspend for a time the operation of this re-agent. This will 
best be seen by the following Table, where the proportions in 
which the two salts were mixed, and the effect produced by the 
subcarbonate of ammonia are briefly stated : 
Subcarbonate of ammonia, in a nearly saturated solution of 
1. Sulphate of Lime alone, - caused an immediate dense cloud. 
2. Sulphate of I.ime, containing 1 gr. f caused no immediate effect, but in a few 
z. ( minutes a cloud as dense as in No. 1. 
of Sulphate of Magnesia in 1 oz. 
3. Ditto, with 2 gr. of Suiphate of ( “ “'’“f ^ 
Magnesia in l oz. I of an hour the solution became as tnr- 
solution became i 
bid as No. 1. & 2. 
caused at first no effect, but in rather 
Ditto, with 5 gr. of Sulphate of i 
TV , ^ ^ ■< more than an hour a shght cloudiness 
Magnesia mloz. | appeai-ed. 
5. Ditto, with 10 gr. of Sulphate of 
caused no effect at all till the next day, 
and then much slighter than in the 
rest. 
Magnesia in the 1 oz. i 
I afterwards tried solutions containing a larger proportion of 
sulphate of magnesia, and, as might be expected, with results 
similar to those obtained in the two last experiments. 
The same influence appears to be exerted on a solution of 
muriate of lime, by the presence of a predominating portion 
of muriate of magnesia ; for the precipitate caused by the addi- 
tion of subcarbonate of ammonia, is, in this case, partially or 
completely redissolved ; whei'eas, in the other, it remains perma- 
nent. 
But not only does carbonate of ammonia appear, from the 
foregoing statement, to b^ at all times an imperfect precipitate 
of lime, and more especially so when magnesia is present, but it 
seems also to throw down a portion of the latter earth, even 
when care is taken not to decompose the triple carbonate of am.^ 
monia and magnesia, by employing heat. 
This I infer from the cloudiness produced, in more than one 
instance, when I redissolved the precipitate thrown down by 
carbonate of ammonia in muriatic acid, decomposed the muriate 
of lime in the same manner as before, and added phosphate of 
soda to the filtered liquor. 
It may strike one at first as singular, that carbonate of am- 
monia should not throw down, on its second application, the 
