150 SCIENCE OF HOME AND COMMUNITY 



of a spiral, embedded in enamel. This enamel is baked to 

 the under side of the top plate. It requires about ten 

 minutes to make the coffee, starting with cold water. In 

 one form of percolator the top may be removed and the 

 bottom part be used for boiling eggs. 



The small disk stoves for heating a small quantity of 

 water for boiling eggs, or any other purpose, are made in 

 much the same way as the bottom part of the coffee per- 

 colator. 



Electric kettle. The electric kettle is a convenient device 

 for heating water. The construction of the lower part in 

 some kettles is similar to that of the coffee percolator. In 

 others the heating element is in the form of a band placed 

 around the outside. In still another form, the heating unit 

 is in the form of a small cylinder, which is immersed in the 

 water. Some kettles are mounted on feet so that they can 

 be placed on the table, without heating the table cover. 



Electric oven. Many kinds of electric ovens have been 

 made. These usually have two iron grids, one at the top 

 and one at the bottom. Each of these has fastened to it 

 pieces of enamel, in which are embedded coils of wire. 

 The heated wires transfer the heat through the enamel to 

 the grid, and then to the air in the oven. These ovens have 

 two walls separated by some substance which does not 

 conduct heat readily. 



Cleaning by electricity. Electricity may be put to many 

 house-cleaning uses. For this purpose we find the electric 

 vacuum cleaner for cleaning carpets and upholstered articles, 

 the electric washing machine and wringer for washing clothes, 

 the iron for ironing them, and the dish-washing machine. 



Electric vacuum cleaner. In the electric vacuum cleaner 

 a motor is arranged to run a fan, which sucks up the dirt 

 through a nozzle which rests on the surface that is to be 

 cleaned. Particles of dust and dirt are picked up and col- 

 lected in a bag attached to the machine. The cleaner is 



