I'LANTS. 



67 



The Capillary Curve. 



stances dissolved in it, will lind their way tliruugli a 



medium whose pores are too small to be seen, even with 



the aid of a microscope. 



3, Capillary Attraction — The attraction of solids and 



liquids for each other, in the case of solids which will not 



dissolve, is shown in the fact that 



the two adhere to each other when 



brought in contact. 



If the edge of a piece of glass is 



dipped into water, the water will 



rise a little distance upon the 



glass, and when it is withdrawn 



some moisture will remain upon 



it. If a small glass tul)e is })laced 



in water, the attraction between 



the t\vo will cause the water to rise in the tube. The 



smaller the tiilje, the higher the water will rise. 



This principle of attraction between 

 solids and liquids, which causes a liquid 

 to pass readily through the minute tubes 

 or pores of a solid, even upward against 

 the force of gravitation, is called capillary 

 attraction, from a Latin word, cajjillxs, 

 which means a hair. The application is 

 to the small, hair-like nature of the tubes 

 througli which the principle works. A 



Direct Capillarity, familiar examjde of ca])illary attraction is 

 the rise of oil in the wick of a lamp. The 



attraction of cotton for oil causes the oil to pass rajiidly 



upward through the pores of the wick. 



If one end of a towel is ]>laced in a l)owl of water, the 



water will gradually ])ass along the cotton or linen fibers 



until the whole towel is moistened. 



