164 INTRODUCTION TO GENERAL SCIENCE 



netting. Carefully invert and remove the card. The water 

 should stay in the glass. Compare Experiment 42. Why 

 does not the water come through the holes in the netting? 



b. Hold the glass over the sink, and with a curved medicine 

 dropper place a few drops of alcohol on the netting. Tell and 

 explain what happens. 



c. Place the little chip of wood upon the water in the cake 

 pan and carefully deposit one drop of alcohol at one end of the 

 chip. Tell and explain what happens. Fill the pan with 

 fresh water, wash the chip, and replace it on the water. Then 

 put a small piece of camphor at one end of the chip so that 

 the camphor is in contact with the water. Describe and ex- 

 plain the result. 



d. Use the funnel as a bubble pipe, and blow a soap bubble. 

 Stop blowing and watch the bubble. Why does it contract? 

 When it becomes straight across the large end of the funnel, 

 what happens? Explain. 



118. CAPILLARITY 



Capillarity consists of those effects of surface tension which 

 are manifested in tubes. If one end of a tube of small diam- 

 eter, open at both ends, is placed in water, the water will 

 rise in the tube above the surface of the outside water. The 

 reason for this is as follows : the force of adhesion between 

 the water and the glass is stronger than the force of cohesion 

 between the water molecules, and the water creeps up the walls 

 of the tube. Immediately the surface of the liquid within the 

 tube contracts, on account of surface tension, and pulls up 

 the rest of the water in the tube. This action continues unti 1 

 the weight of the water in the tube equals the force of adhesion. 

 The smaller the tube is, the higher the water rises. 



Examples of capillarity are everywhere present. Blotting 



