ON CAPILLARY ACTION. $ 



that no antjular termination, of a fluid in contact with a so- Angular ter- 

 . 1 .1 J '^L r u.^ 1- 1 I A rnination of a 



lid can remain at rest, unless the density ot the solid ue (:i^,j^j-,j^q^j^j,j 



precisely half that of the fluid. Thus if A B (Fig. 2) be with a golid 

 ^ „ ,. r. . 1 ' 1 • 1 • ^ 1 -^ i- 1 cannot Vemaiii 



the surliice of a fluid retained in a horizontal situation by ^t rest, unless 



the vortical force C D, resulting from the joint actions C E the density of 

 and C F of the wedges A C H and B C H, Jf we add a [h^t^of ^jj *^ 

 t\'edge B C I opposite and similar to A C H, we shall have fluid exactly as 

 a straight line H I, and the action C K of this' wedge re- 

 ducing C E to C L, that of the wedge B C H must be re- 

 duced in the same proportion, in order that the result may 

 remain in the direction C D, and the density of B C H 

 must be made equal to the difference of the densities of 

 B C I and A C II ; or, if H I be the termination of a sin- 

 gle solid, that solid must be of half the density of the fluid. 

 It was perhaps in order to avoid this inference from his first 

 theory, that Mr. Laplace adopted afterwards a different .^ 



mode of reasoning. 



I shall now examine the consequences of the supposition Consequences 

 of a repulsive force extending its action to all particles fo;^feJ^^^" '''^^ 

 within a certain very small distance of each other. Since it 

 is certain, that the particles of all bodies in the state of gas P<:;rticles of gas 



repel each other, without any thinaj like the actual contact [^i^*^!.^^ ^®'^^^' 

 " ' "^ y Die distances, 



of impenetrable atoms ; and since it may be shown by ex- as do many so- 

 periment, that many solid bodies exert repulsive powers on ^^''^^ 

 each other at sensible distances; it is natural to imagine, 

 that the repulsive force, acting on any given particle, is de- 

 rived from the joint effect of a considerable number of other therefore re- 

 particles at different distances from it, in the same manner pulsion the ^ 

 as the force of cohesion is conceived to be derived from the many particles, 

 joint actions of a great number of particles cooperating with 

 eacli other; although the repulsive force may naturally be ^nd probably- 

 supposed, to consist principally in the stronger action of a from the 

 smaller number of particles. Now if the circle A (Fig. 3) ^f fewer parti- 

 represent the limits of the force of cohesion, and B those of dt's than ope- 

 the force of repulsion acting on the ceiitral particle C, it is l^^^ ^^ ^^ ^' 



evident, that, if the substance be divided into any number ^,. ,. ,. 



J This applied to 



of wedges meeting in the point C, the two f^^rces exerted sectors of cir- 

 by any one of these D C E, upon any other F C G, must ^^^^• 

 be equal, since the segments are in the same proportions as 

 the whole circles ; and the effects of the whole circles are 



B 2 equal : 



