158 MODERN SCIENCE READER 



the problem of its production by an adaptation of the 

 "oxygen-nitrogen" arc apparatus, and utilizing the same 

 principle of introducing the material into the arc and very 

 rapidly cooling the products obtained. We mention this 

 not because of its great commercial importance at present, 

 but because it shows how the "arc method" may be of 

 wide application in solving other difficult chemical prob- 

 lems; it has opened before us a new method in chemical 

 science, and may give birth to many and various new 

 chemical industries. 



///. . Electric Furnaces 



Electric furnaces are furnaces in which the necessary 

 heat or degree of temperature is produced or attained by 

 means of electrical energy. The electric current is used in 

 these furnaces solely for its heating or thermal effect, and 

 either alternating or direct current may be used, but alter- 

 nating is preferred because of its easier generation and 

 management, capability of being procured from transform- 

 ers, and absence of electrolytic effects. 



Electric furnaces render remarkable and highly valuable 

 service to the chemist and metallurgist, for two distinct 

 and unique capabilities; they can generate heat within 

 themselves without the use of combustion and the conse- 

 quent products of combustion to complicate the working 

 of the furnace, and they can besides, if desirable, produce 

 temperatures absolutely unapproachable in furnaces using 

 fuel, and thereby enable the carrying out of operations 

 only possible at these extremely high temperatures. The 

 upper limit of electric furnace temperature is simply the 

 volatilizing point of carbon, the temperature at which the 

 material of which the lining of the furnace is made is 

 boiled away. This is about 3,700 C. or 6,692 P. The 

 simple statement that this is three times as high as the 

 melting point of cast iron may give some notion of the 

 enormous temperature here at one's command. Besides 

 high temperature, the efficiency of application of electrical 



