Dr ■Daubciij (m separating Lime from Magnesia. 
of muriate, or sulphate of magnesia, so that we may be sure, 
from the proportion they bear to each other, that the re-agent 
is not in excess ; and if a single drop of this mixed liquor be 
added to water containing lime in any of its states of combina- 
tion, the precipitation which ensues will convince us of the cor- 
rectness of the Tables in this instance. 
Although, in the experiments above detailed, I confined mv- 
self to solutions of the two sulphates, I have since found that 
muriate of lime is likewise rendered' much less sensible to the 
action of the same test by the presence of a predominating 
proportion of muriate of magnesia’^; so that we ought al- 
ways to be cautious in inferring the absence of lime, from the 
circumstance of no change occurring upon the addition of an 
oxalate, when the solution is found to contain any considerable 
quantity of magnesia. 
It appears, however, that where the proportions of the two 
earths present are more nearly balanced, the use of the oxalic 
test is open to an objection of quite the opposite kind, the pre- 
sence of magnesia serving in this case to increase instead of di- 
minishing the quantity of precipitate obtained. On this subject, 
however, I shall bring forward nothing of my own, as my 
friend Professor Kidd of this University, has been kind enough 
to put into my hands a statement of some experiments on this 
subject, instituted by himself many years ago, and therefore 
without any reference to the present inquiry. The following is 
an outline of these experiments. 
July 14. 1812. — Dr Kidd took 50 grains of the calc-sinter, 
deposited from the waters at Matlock, and dissolved it in nitric 
acid. Oxalate of ammonia being then added, until its action 
ceased, a precipitate w.as collected, which, when carefully dried 
at a temperature scarcely exceeding 80°, yielded 71 grains. 
He treated 20 grains of pure carbonate of lime, procur- 
ed from lime-water, in a manner precisely similar, and obtained 
80 grains of oxalate of time. 50 grains of the same would 
therefore liave yielded 75 grains of the oxalate. 
* This fact, I find, is noticed by Mr Phillips in his paper in the Journal of 
Science, so often alluded to. 
VOL. VII. NO. 14. OCT. 1822. X 
