Sxry.—On Tomlinson's Cohesion Figures. 493 
in consequence of this, exercises the property of adhesion to the greatest 
extent in respect to its own parts, hence it coalesces in those annular 
elevations which form the principal feature in the cohesion figures of Prof. 
Tomlinson. 
I will conclude this paper by informing you that I consider this change 
of oil into resinoid substances helps largely to produce those rapid changes 
of colour which oil exhibits when exposed to the air upon a surface of water ; 
indeed, it appears to me that the effect of those chemical changes which 
must take place in certain liquids when exposed to the air or brought into 
contact with each other, has been ignored by.those persons who have 
hitherto investigated the subject of the flow of liquids upon each other. 
