on the Cohesion of Fluids. 81 
and the same inclination will serve for a larger or a smaller 
drop at the same place. Now when the drop approaches to 
the line of contact, the difference of the appropriate heights for 
a small drop of a given diameter will increase as the square of 
the distance decreases ; for the fluxion of the reciprocal of any 
quantity varies inversely as the square of that quantity : and, 
in order to preserve the equilibrium, the sine of the angle of 
elevation of the two plates must be nearly in the inverse ratio 
of the square of the distance of the drop from the line of 
contact, as it actually appears to have been in Hauksbee’s 
experiments. 
VI. Physical Foundation of the Law of superfcial Cohesion. 
We have now examined the principal phenomena which are 
reducible to the simple theory of the action of the superficial 
particles of a fluid. We are next to investigate the natural 
foundations upon which that theory appears ultimately to rest. 
We may suppose the particles of liquids, and probably those 
of solids also, to possess that power of repulsion, which has 
been demonstratively shown by Newton to exist in aeriform 
fluids, and which varies in the simple inverse ratio of the 
distance of the particles from each other. In airs and vapours 
this force appears to act uncontrolled ; but in liquids, it is over- 
come by cohesive force, while the particles still retain a power 
of moving freely in all directions ; and in solids the same 
cohesion is accompanied by a stronger or weaker resistance to 
all lateral motion, which is perfectly independent of the co- 
hesive force, and which must be cautiously distinguished from 
it. It is simplest to suppose the force of cohesion nearly or 
perfectly constant in its magnitude, throughout the minute 
MDCCCV. M 
