crease the drop-size. Hence an increase of cohesion tends 
to produce two contrary effects. But if there he a similar 
distinction between the two kinds of cohesion of liquids as 
above pointed out in the case of solids, we have the following 
consequence. 
It is the persistent cohesion which causes the assumption 
of the spherical form : the stubborn which resist the separa- 
tion of the drop. The former tends to diminish the latter to 
increase its size. As one or other predominates, the size of 
the drop varies. 
Accordingly, the drop-size is by no means a measure of 
what is generally called the cohesion of the liquid : but rather 
a measure of the difference between the two cohesions stub- 
born and persistent : and the law is that the drop-size varies 
inversely as its persistent and directly as its stubborn co- 
hesion. 
In mercury, water and glycerine the stubborn cohesion is 
greater in proportion to the persistent cohesion than in the 
other liquids examined : but it by no means follows that per- 
sistent cohesion is wanting in mercury or stubborn in alcohol. 
When a drop is in the act of falling its stubborn cohesion 
is in equilibrium with the resultant of two forces ; the one, 
the persistent cohesion tending to produce a spherical form, 
the other the weight of the drop. Since the former of these 
component forces is, for the same liquid constant, it seems as 
though the weight of the drop might be taken as a measure 
and expression of the stubborn cohesion. But such is not 
the case, because we have no ground for supposing that the 
diameter of the drop where the separation occurs, is of cons- 
tant size : on the contrary, it must be conceded that in large 
drops, this hypothetical surface of stubborn cohesion is larger 
than in smaller drops. Further, unless we know the exact 
shape of a drop in all cases we are not in a position to deduce 
the size of the surface of cohesion from the drop-size or drop- 
weight. 
In the cases whese it has been tried it has not been found 
