150 HOW WASTES ARE REMOVED FROM THE HOME 



A flush tank. If you will examine the diagram accom- 

 panying this paragraph carefully, you will find that water 

 gets into the tank through the action of the ball float, 

 which, when the toilet is flushed, opens a valve and allows 

 a new supply of water to come into the tank. When the 

 water reaches a certain level the float automatically closes 

 the valve. The toilet itself is flushed by pulling a lever 



The bathroom flush tank. 



which opens the valve at the base of the siphon. As the 

 water begins to flow this valve closes, and the water in the 

 pipe leading to the toilet acts as the plunger of a piston (see 

 diagram) , and water is passed into the flush pipe through 

 the siphon. As soon as the water in the tank is lowered 

 to the point D the siphon tube fills with air and the action 

 stops. The tank then fills up as has been shown pre- 

 viously. 



The study of your own home flush tank makes an inter- 

 esting experiment. 



