OF CAPILLARY ATTRACTION AND THE COHESION OF FLUIDS. 437 



555. EXPERIMENT 2. If the two floating bodies are not capable of 

 being wetted with the fluid, such as two balls of iron in a vessel of 

 mercury, and if they are placed at the distance of a few lines, they will 

 move towards each other with an accelerated velocity; and if the vessel 

 is made of glass, in which the surface of the mercury is always convex, 

 the bodies will move towards the side when they are placed within a 

 few lines of it. 



556. EXPERIMENT 3. If one of the bodies is susceptible of being 

 wetted with water, and the other not, such as two globules of cork, 

 one of which has been carbonized with the flame of a taper ; then, if 

 we attempt, by means of a wire or any other small stylus, to make the 

 bodies approach, they will fly or recede from each other as if they 

 were mutually repelled; and if the vessel is of glass, having the 

 carbonized ball of cork placed in it, it will be found impossible to 

 bring the cork in contact with the sides of the vessel. 



In these experiments it is manifest, that the approximation and 

 recession of the floating bodies, are not produced by any attraction 

 or repulsion between them ; for if the bodies, instead of floating on 

 the fluid, are suspended by slender threads, it will be observed that 

 they have not the slightest tendency either to approach or recede, 

 when they are brought extremely near to each other. 



From an attentive consideration of the phenomena exhibited in 

 these experiments, we may deduce the following laws. 



557. (1.) If two bodies, capable 

 of being wetted by a fluid, are 

 placed upon its surface and 

 brought near to each other, they 

 will approach as if they were 

 mutually attracted. 



For if two plates of glass AB, 

 CD are brought so near each 

 other, that the point H, where 

 the two curves of elevated fluid 

 meet, is on a level with the rest 

 of the mass, they will remain in 

 a state of perfect equilibrium. 



If, however, they are brought 

 nearer together, the water will 

 rise between them to the point 

 G ; the water thus raised, attracts 

 the sides of the glass plates, and 



D 



