ON THE DIFFUSION OF LIQUIDS. 
169 
clear liquor ; but it may be prepared by other means. As 
different sugars differ in their qualities, no exact rule can be 
given as to the quantity of acetate of alumina to be used; but 
the operator will readily ascertain the quantity required in 
each case, by taking a sample of the juice or sugar, and test- 
ing it with a measured quantity of acetate of alumina. The 
patentees have found that the best effect is produced on a 
fair sample of Jamaica sugar, by employing at the rate of 
four pounds of alumina, dissolved in acetic water, to one 
ton of sugar.— Chem. Gaz., Nov. 16th, 1849. 
ART. XLIL— ON THE DIFFUSION OF LIQUIDS. 
BY PROFESSOR GRAHAM. 
r Abstract of the Bakerian Lecture, delivered before the Royal Society, 
21st December, 1849.] 
The Lecturer commenced by observing, that a salt or 
other soluble substance once liquified and in a state of so- 
lution, is evidently spread or diffused uniformly through the 
mass of the solvent by a spontaneous process. It has often 
been asked whether this process is of the nature of the dif- 
fusion of gases, but no satisfactory answer to the question 
appears to be obtained, owing, he believed, to the subject 
having been studied chiefly in the operations of endosmosis, 
where the action of diffusion is complicated and obscured 
by the imbibing power of the membrane, which appears to 
be peculiar for each soluble substance, but not necessarily 
connected with the diffusibility of the substance in water. 
Gay Lussac proceeded upon the assumed analogy of gaseous 
and liquid diffusion in the remarkable explanation which 
he suggested of the cold produced on diluting certain saline 
solutions, namely, that the molecules of the salt expand into 
the water like compressed gas admitted into additional space- 
The phenomena of solubility were at the same time con- 
