98 THE NATURE STUDY COURSE. 



called capillarity. Illustrate it by hanging a damp cloth over 



the edges of two tumblers, into one of which a quantity of 

 water is put, or by setting up in a saucer 

 of inky water two small squares of glass 

 touching at one edge and separated 

 slightly at the other. The black water 

 will rise nearly to the top at the edges 

 in contact. An oven-dried brick may 



be set on end in a saucer of water to exhibit the same 



phenomenon. 



Take one of those tin cans with the holes in the bottom 

 used in the last experiment. Fill it with quite dry soil and 

 set it in a saucer of water, adding water from time to time if 

 necessary. Lay a pane of glass over the top of the can and 

 observe when moisture appears. The can of soil may be 

 weighed before and after to determine the weight of 

 water absorbed by capillarity. 



If lamp chimneys are used and different kinds of soil put 

 in them the pupils may observe the different degrees of 

 rapidity with which the water ascends in each. They can 

 infer that the faster the water comes to the top the more 

 rapidly it will evaporate at the surface, and hence why sandy 

 soils dry so much more quickly than clay ones. The pupils 

 have already seen how much faster water drains downward 

 through it. 



