438 



MESSRS. R. S. HUTTON AND J. E. PETAVEL ON ELECTRIC 



During the experiment the voltage and current are read at frequent intervals ; the 

 watts, at these instants, plotted on a curve enable the total kilowatt hours supplied 

 to the furnace to be obtained by integration. 



B 



A. 



B. 



D 



c 



-b 



-a 



Fig. 11. Sectional views of various types of electric furnace. 



A. Smothered arc (before run). 



I is the cast-iron liner in which the charge was placed, h, cover of same, e, vertical 

 carbon electrode (41 millims. diameter), d, granular carbon bed forming the lower 

 electrode, c, charge. 



AI. Smothered arc (after run), 



a, ingot of fused product, b, fused and fritted material forming walls of cavity, c, unacted- 

 i m material. 



B. Itesislance (before run). 



e, carbon electrode. /, graphite end-piece leading current to core, g, resistance core of 

 granular material or carbon rod, or other solid " resistor." c, charge, d, granular 

 carbon bed or other form of lower electrode. 



BI. Resistance (after run). 



a, ingot of fused product, b, fused and fritted material forming walls of cavity, c, unacted- 

 on material. 



C. Horizontal arc : radiation heating. 



i, e 2 , electrodes. /, walls or jacket of heat insulating material, c, charge in carbon or 

 other crucible. 



D. Smothered arc unth two carbons embedded in the material (used horizontal or vertical position). 



e\, a, electrodes, r, charge. 



