210 WATER, HEAT, AIR, AND LIGHT IN THE HOUSE 



(2) Those in which the opening is closed by a rubber " plunger," or 



Waste water, like that from a sink or bowl, is discharged into the 

 sewer pipe through a trap (Fig. 200). This is a bend in the pipe, 

 which remains full of water, and cuts off connection between the air of 

 the room and that of the sewer. Water should be 

 I* From sink run every few days into sinks and floor drains that 

 are little used, so that the traps may always be full. 



, 237. Kindling a Fire. The discovery 



Sediment J 



Drain Plug of fire came long before the dawn of history. 



To Waste Pipe > ... , ... 



Fig. 200. Many primitive peoples still start their 

 A Trap. res by jobbing one piece of wood against 



another. The friction gives the temperature needed to 

 set on fire the bits of bark, pitch, dry fungus, etc., that 

 serve as tinder (cf. Fig. 63, 76). A century ago the 

 kindling method used in Europe and America was to 

 strike steel or iron pyrites (a compound of iron and sul- 

 phur) against flint. In the flintlock musket this method 

 was used to kindle gunpowder. 



The first practical friction matches were made about 

 1827. They consisted of wooden splints partly coated 

 with sulphur, and tipped with potassium chlorate, anti- 

 mony sulphide, and gum. Friction against a rough sur- 

 face produced heat enough to make the sulphur unite 

 with the oxygen of the potassium chlorate, and the heat 

 of the burning sulphur set the wooden splint on fire. The 

 "parlor" match has a tip containing paraffin or sulphur, 

 yellow phosphorus, and some oxidizing substance like 

 potassium chlorate or "red lead." Glue is used to make 

 all the substances adhere to the wood. 



Parlor matches are ignited much more easily than 



