22 BULLETIN 600, U. S. DEPARTMENT OF AGRICULTURE. 
THE ELECTRIC FURNACE. 
The inner case of the furnace is made of alundum on which is 
wound nichrome wire of 0.072-inch diameter. The resistance of the 
furnace is 12 ohms. At the rear an alundum tube is inserted to lead 
off the volatile matter to a cooling cylinder of metal which is con- 
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2.—Details of regulating devices. 
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nected to a bottle containing water and small pieces of pumice. The 
other opening of the bottle is connected with the suction. Asbestos 
wool forms the insulating material between the alundum case and 
the asbestos-board outer form. The door of the furnace is mounted 
with double hinge and weighted to remain open or closed, as placed. 
