SCIENCE OF HOME AND COMMUNITY 



the water. Why does the water remain in the tube ? Remove 

 your finger. Why does the water fall ? 



Fill a tumbler with water. Over the top place a piece of 

 paper and press it down firmly on the rim. Hold the paper 

 on with one hand and invert the tumbler with the other. Re- 

 move the hand from the paper. What keeps the paper up ? 



4. Submerge a piece of rubber tubing about a foot and a half 

 long in a dish of water till the tube is full of water. Pinch one 

 end of the tube with the thumb and finger and. ^ ring it out over 

 the edge of the dish into another empty dish placed alittle loWer 

 than the first. Remove the hand. What makes the water 

 flow ? Raise the second disK higher than the first, keeping the 

 end of the tube under water and note what happens. A tube 

 used in this way is called a siphon. 



Light a piece of paper and drop it into a pint milk bottle. 

 After the flame goes out, put a hard-boiled egg with the shell 

 removed in the mouth of the bottle. How do you explain what 

 happens? 



6. Do these experiments help you to explain the working of 

 a fountain-pen filler and why it is possible to drink soda water 

 by means of a straw ? 



LABORATORY EXERCISE 8 



Purpose. To show how a pump works. 



Apparatus. A small cistern pump or a glass model of a lift 

 pump. 



Directions. Operate the pump and note carefully how it 

 works. Take it apart and examine the various parts. Make 

 i wing of the pump and explain how each part works. 



Lift pump. If the well is deeper than thirty-two feet, a 

 lift pump is used. In this kind of pump, both valves are in 

 a movable cylinder, which may be placed in a large pipe, 

 within thirty-t -,vo tVrt of the surface of the water. The 

 pressure of the air forces the water up to the cylinder, and 

 from here it is lifted by means of a rod attached to the 

 at one end and to the pump handle at the other. 



