166 MODERN SCIENCE READER 



which the Heroult furnace is the most familiar type, works 

 with two arcs in series, the current entering the bath and 

 leaving it also through electrodes suspended above it. The 

 general style is that of an open-hearth furnace with elec- 

 trodes passing through the roof. The current used is 

 roughly 100 kilowatts per ton of steel capacity, and the 

 largest so far operated is 15 tons. A three-ton furnace of 

 this type was seen by you at the Firth-Stirling Steel Works 

 at Demmler, yesterday, producing crucible-quality steel. 

 The U. S. Steel Corporation has acquired licenses to operate 

 the Heroult furnace, and has already two 15-ton furnaces 

 in operation. Without doubt, the Heroult furnace is at the 

 present time the most popular and successful electric steel 

 furnace in the United States. I have not time to more than 

 name the Keller, the Hiorth, the Harmet, the Frick all of 

 which are operating at this present moment, in Europe. 



There are other ways of making steel than the crucible 

 method. Bessemer steel is the cheapest, and open-hearth 

 steel is next best. These two varieties grade into each other 

 in quality, but between open-hearth and crucible steel there 

 is an enormous gap in price and in quality which is destined 

 to be bridged over by intermediate qualities of electric steel, 

 as it becomes cheaper and is manufactured on a larger 

 scale. This will soon become one of the large uses of the 

 electric method, occupying a field peculiarly its own. It 

 will enable steel manufacturers to supply steel better than 

 the best open-hearth product at less than the price of 

 crucible steel. I need not enlarge upon the advantages of 

 this to a Pittsburg audience. 



There are also varieties of methods of manufacture of 

 steel, aside from the melting together of highly pure ma- 

 terials as in the crucible method, which are equally avail- 

 able in most types of the electric furnace. The Bessemer 

 converter takes liquid pig iron as it comes from the blast 

 furnace and by rapid oxidation by air blast converts it 

 into steel. Mr. Heroult has tried to combine the Bessemer 

 converter with the electric furnace, in one apparatus, the 



