ELECTRICITY. 



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metallic plate P, and surrounded by a mass of carbon, C, the whole 

 being enclosed by the furnace wall M. D is a carbon rod, and acts 

 as the anode, while connection through the metallic plate is made 

 with the cathode from below. 



Fig. 32 gives a sectional, and Fig. 33 an exterior, view of an elec- 

 tric furnace used in the manufacture of carborundum. The current 



FIG. 32. 



Longitudinal section of carborundum furnace. 



enters and leaves through the cables which terminate in carbon elec- 

 trodes fastened in the wall. Between the electrodes is a mass of 



FIG. 33. 



Exterior view of carborundum furnace. 



coke, which, while conducting the current, offers sufficient resistance 

 to be heated to an extremely high temperature. (For details of the 

 chemical action see the article on Carborundum.) 



The electric arc lamp and the incandescent lamp are well-known examples 

 of the conversion of electrical energy into light. In the former lamp electricity 

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