300 



THE ELECTRIC FURNACE. 



Fig. 5. 



truck ]>ocome.s lilU'd with ;i l»l()ck or ina.ss of calciuni carbide and is 

 then wheeled out of the furnace to discharge its h)ad. Wliih' fusion 

 is in progress a slight reciprocating motion is given to the truck, 

 which serves to shake the charge well down and introduce fresh por- 

 tions of it into the path of the arc proper. 



The Chavarria-Contardo arc furnace for 

 the manufacture of calcium carbide pos- 

 sesses several novel ])oints. Its general 

 principle is represented diagrammatically 

 in tig. 5, where e e are the electrodes, run- 

 ning parallel to one another and slightly 

 al>ove the axis of the channel or trough 

 T, which forms the hearth; c e are thin 

 gra})hite plates, built up to form a roof- 

 shaped structure, which I)ecomes itself 

 intensely hot when the furnace is active. 

 The raw^ material is fed in at A, and, pass- 

 ing over the upper surfaces of c c, receives 

 a ])i'elimiiiary heating of no mean degree; 

 it then passes down, taking the course 

 indicated by the dotted lines, under the 

 electrodes e e and into the trough T, where it is su])jected to the most 

 intense reflected heat of the are. The molten carbide formed is drawn 

 off l)y wa}' of the outlet o. 



The disposal of the gases, especiall}' carl)on monoxide, resulting 

 from the reactions in a carbide furnace has long be(Mi a stumbling 

 block to the manufacturer in that any attempt at modifying the furnace 

 to this end resulted in luidesira- 

 ble complications and increased 

 prime cost. This has been, in a 

 measure, overcome in theFrolich 

 arc furnace for car])ide manufac- 

 ture, invented l)y Dr. Oscar Fro- 

 lich. of Streglitz, Germany. The 

 general arrangement is shown 

 in tig. 6 and consists of a cylin- 

 drical iron cruci])le F, mounted 

 on standards S, and tapering at 

 its base to a central discharge 

 orifice. 



A lining of lire clay L protects 

 the cylindrical W'all, while the 



inner surface of the conical base is covered by the carbon electrode C. 

 The remaining electrode consists of the massive carbon cylinder B, 

 which is hollow, and depends, with its lower edge just over the dis- 

 charge oritice, the arc taking place between the two edges of the 



