Hotter than Hell

Oldtime theologians thought of hell in terms of fire and brimstone--volcanic heat coming from inside the earth, whose core is probably no hotter than 1,500DEG C. Modern electrical engineers can produce steady temperatures of 2,000DEG C. in furnaces for the steel industry, and fortnight ago Chemist Robert Browning Sosman of U. S. Steel Corp. announced that with a heliostat and focusing mirror he had been able to capture 3,000DEG of the sun's heat (TIME, Dec. 21). With gas, temperatures as high as 4,600DEG have been obtained, but they could not be maintained long. Last week Engineer Frank T. Chesnut of Ajax Electrothermic Corp. designed a furnace capable of 3,600DEG, with a controlled heat over a long period of 3,000DEG, and for the first time the action of such a temperature could be studied. Engineer Chesnut predicted that his furnace could be made still hotter under pressure.

Electric furnaces are built on the principle that when electrical energy meets resistance it is converted into heat energy. Well known is the Ajax Northrup high frequency furnace which increases the heat energy by creating a current in the material to be melted. Using this principle, Engineer Chesnut made an experimental furnace of 1 cu. ft. capacity. The crucible was lathed out of a solid block of graphite, a form of carbon which conducts electricity well. To set up the resistance he packed the crucible in lampblack--an obstinate conductor of electricity. The current was carried through a copper coil. The outside of the furnace was heat-insulated, and a temperature gradient was established through the heat insulation to a water-cooled inductor coil. This carried the heat away, prevented the outside of the furnace from getting hot and breaking down the charge coil, which had spoiled earlier efforts to maintain high temperatures.

As the current was turned on the graphite interior of the crucible quickly grew white hot. Through one of two small tubes in the cover of the furnace Engineer Chesnut, wearing dark glasses, could peer, and so good was the insulation that he could put his eye within a few inches of the tube. Keeping the temperature at 3,000DEG--600DEG below the vaporization point of graphite--Engineer Chesnut could drop objects through the tube, watch what happened in the hellish interior. Wood was instantly reduced to vapor, burning as a sudden jet of gas. Rocks quickly became vaporized, silicon and magnesium gases shot out into the air burning with a white flame. The furnace was kept at 3,000DEG for more than five hours. Iron was put in. It turned to gas, formed a carbide, remained as such while the temperature was raised toward the 3,600DEG vaporization point of graphite. At this point a blue & white flame shot out of the opening. Experimenter Chesnut, trying for a still higher temperature, left the power on an instant too long. Graphite and iron carbide vaporized suddenly. The inside of the furnace burned away, the circuit broke, Engineer Chesnut had to build a new machine to play hell.

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