264 REPORTS ON THE STATE OF SCIENCE 



but has an important addition. In its simplest form for single-phase 

 current there are two grooves or heating channels corresponding to the 

 annular crucible of the Kjellin, but these join to a central open-hearth, 

 the whole hearth forming a kind of figure 8. Tn the central open- 

 hearth all the distinctly metallurgical operations take place, so that 

 this form can be used for refining work for which the Kjellin is not 

 very suitable. Not only so, but a distinct secondary winding is pro- 

 vided in which a secondary current is induced, and these windings are 

 joined to steel terminal-plates which are embedded in the refractory 

 material of the furnace at the ends of the central hearth. At high tem- 

 peratures the refractory material becomes a conductor of electricity and 

 thus the currents induced pass through the bath in the central hearth, 

 heating it still further. 



There are many others, some only on paper, but these are the prin- 

 cipal varieties that have been tried with any considerable degree of 

 success. The loss in melting is an important point, and I am informed 

 that this amounts to about 1| per cent, in the Kjellin, about 4 to 5 in 

 the Eochling-Kodenhauser, and 7 to 8 per cent, in arc furnaces. 



In considering the present position of the electric steel-melting 

 industry regard must be had to the numbers and capacities of the various 

 types of furnaces in work, not in work, and being built, although a com- 

 plete survey should also take account of the nature and quality of the 

 materials being made, for a furnace making a ton of high-speed steel 

 should obviously be credited with more importance in the commercial 

 world than one making a ton of steel for rails. The progress in num- 

 bers and capacities and in output should also be considered. So far as 

 one could ascertain, about June 1910 there were about 118 furnaces of 

 all types, of which 70 were in use, 10 not working, and 38 being built. 

 There were 77 of the arc furnaces recorded, of which 29 were credited 

 as He>oult, 17 Girod, 13 Stassano, 6 Keller, and 9 others; besides one 

 furnace at Domnarfvet, Sweden, for the production of 2,500 tons of 

 pig iron per annum, with one in Norway and one at Trollhattan, 

 Sweden, both in course of construction and each designed to produce 

 about 7,500 tons of pig iron annually. Of the Heroult furnaces the 

 total capacity per charge of those working was about 80 tons and of 

 those in course of construction about 50 tons. The Girod furnaces, the 

 great competitors of the Heroult, were recorded at about 38 tons in 

 work and 26 tons being built. Similarly the figures for the Keller were 

 13 tons and 5 tons, and for the others 20 tons and 13 tons respectively. 



Of the induction furnaces the Kjellin furnaces erected totalled four- 

 teen with 35 tons capacity, the Kochling-Rodenhauser fifteen, with 30 

 tons in work, 1 ton not in work, and 17 tons capacity being built, all 

 others about 18 tons in work. That gave a total capacity of about 250 

 tons for the arc furnaces and 100 tons for the induction, or a grand 

 total of 350 tons per charge for all electric steel-melting furnaces. 

 Pressure of other work has prevented me getting the latest figures from 

 all the firms making electric furnaces, but I have obtained these from 

 the two most important firms, viz., the Hdroult and the Kjellin and 

 Kochling-Rodenhauser, and in this connection would record my best 

 thanks to Mr. Donald P. Campbell, B.Sc, A.R.S.M., and Mr. E. C. 

 Ibbotson respectively for their kind help and trouble in getting me this 



