( 108 ) 
Art. XVIII . — On the Methods oJ‘ separating Lime from Mag- 
nesia By C. Daubeny, M. D. M. G. S. 
It has often struck me, that the discordant results which the 
experiments of different chemists so often exhibit, where the 
analysis of the same substance is attempted by different means, 
may in part be explained, from their overlooking the affinity 
which mutually subsists between two salifiable bases, or be- 
tween the compounds which they respectively form with acids, 
when both are dissolved in a common menstruum. 
I do not pretend, indeed, to bring forward as original, an ob- 
servation too obvious in its nature not to have occurred to other 
chemists* *!’; and I even recollect, that the late ingenious Dr 
Murray, whose death is so great a loss to science in general, and 
to this branch of it in particular, appeals to the above principle, 
in attempting to account for the manner in which substances 
that, under existing circumstances, are found to be sparingly 
soluble in water, might have been brought into combination 
with it, by the co-operating affinity of other bodies already con- 
tained in the general solvent 
It nevertheless appears to me, that this circumstance has been 
too little attended to as affecting the operation of the general 
laws of affinity between bodies in opposite electrical states, al- 
though its importance will be obvious, from a very few conside- 
rations. 
• Read before the Wernerian Society, 18th May 182^. 
*1* Dr Young, in his Numerical Table of Elective Attractions, published in the 
Philosophical Transactions for 1809, remarks, “ It is not impossible that there 
may be cases in which the presence of a fourth substance, besides the two ingre- 
dients of the salt, and the medium in which they are dissolved, may influence the 
precise force of their mutual attraction, either by affecting the solubihty of the salt, 
or by some other unknown means ; but there is reason to think that such cases are 
rare.” I am disposed to differ with that acute philosopher on the latter point ; 
but am happy to adduce the authority of his name in favour of the possibility of 
such an accident. 
4: See his “ Comparative view of the Huttonian and Wernerian Theories,” 
which is perhaps the best answer that has yet appeared to Mr Playfair’s, eloquent 
work. 
