66 



SCIENCE OF COMMON THINGS. 



"Watering plants. Cotton lamp-wick. 



Blotting paper absorbs ink. 



fig. 18. 



themselves into the pores of the sugar by capillary 

 attraction* and force the crystals apart from each 

 other. 



4OS What is capillary attraction ? 



The power which very minute 

 tubes possess of causing liquid to 

 rise in them above its level. 



" Capillary," from the Latin word, " capil- 

 laris" (like a hair) ; the tubes referred to are 

 almost as fine and delicate as a hair. Water 

 ascends through a lump of sugar or pieee of 

 sponge r by capillary attraction. 



N. B. The smaller the tube, the higher will 

 the liquid be attracted by it. Fig. 18 illus- 

 trates the manner in which water will rise in 

 tubes of different diameters. 



403 Why is vegetation on the margin of a river more luxuriant than 

 in an open field ? 



Because the porous earth on the bank draws up too-. 

 ter to the roots of the plants by capillary attraction. 



404 Why do persons who water plants very often pour the water into 

 the saucer, and not over the plants ? 



Because the water in the saucer is drawn up by the 

 mould (through the hole at the bottom of the flower- 

 pot), and is transferred to the stem and leaves of the 

 plant by capillary attraction. 



405 Why is cotton best adapted for lamp-wicks f 



Because the arrangement of the fibres of the cotton- 

 wick is such, that the whole forms a bundle of minute 

 tubes, in which the oil ascends and supplies the flame 

 by capillary attraction. 



406 Why does blotting-paper absorb ink f 



The ink is drawn up between the minute fibres of 

 the paper by capillary attraction. 



407 Why will not writing or sized paper absorb ink f 



Because the sizing, being a species of glue into 

 which writing papers are dipped, fills up the little in' 

 terstices or spaces between the fibres, ana in this way 

 prevents all capillary attraction. 



408 How does a sponge absorb water t 



