CAPILLARY ATTRACTION. 



47 



dew upon the blade of grass ; in the other, gravitation, 

 acting in like manner, but at vast distances, gives the 

 mighty rotundity to the rolhng waters of the ocean. 



CAPILLARY ATTRACTION. 



Capillary attraction is a species of cohesion ; it 

 takes place only between solids and liquids. It is this 

 which holds the moisture on the surface of a wet body, 

 and which prevents the water from running instantly 

 out of a wet cloth or sponge. By touching the lower 

 extremity of a lump of sugar to the surface of water 

 in a vessel, capillary attraction will cause the water to 

 rise among its granules and moisten the whole lump. 

 It may be very distinctly shown by placing the end of 

 a fine glass tube into water ; the water wiU rise in it 

 above the level of the surrounding surface. If the bore 

 of the tube be the twelfth of an inch in diameter («, 

 Fig. 15), it wiU rise a quarter of an inch ; if but the 



Fig. 15. Fig. 16. 



Capillary attraction in tidies. 



Capillary attraction between two panes of 

 glass. 



twenty-fifth of an inch in bore, as b, it will rise half an 

 inch ; but if only a fiftieth of an inch, the water will 

 rise an inch. This ascent of the liquid is caused by 

 the attraction of the inner surface of the txibe, until the 



