790 POPULAR SCIENCE MONTHLY. 



an address by W. R. Addicks, of Boston, Mass., delivered before 

 the New England Association of Gas Engineers at tbeir twenty- 

 sixth annual meeting : 



The electric furnace is of ordinary brick, two and a half by 

 three feet (inside measurements) at the bottom. The front side 

 consists of four iron doors. The electric current enters at the 

 bottom and top ; the lower electrode is an iron plate covered with 

 eight inches of carbon (pieces of carbon pencils or a mixture of 

 coke and coal tar). Sixteen copper cables 075 inch in diameter 

 convey the electricity from the dynamos to the bottom electrode ; 

 sixteen other cables are connected with the top electrode, which 

 is composed of six carbon pencils each four inches square and 

 thirty-six inches long ; these are bound together by a sheet of 

 iron, so as to really form only one pencil. The upper electrode 

 is so arranged that it can be raised or lowered by means of a 

 screw. Dynamos giving a current of from fifty to one hundred 

 volts and seventeen hundred to two thousand ampferes are used, 

 actuated by a water wheel of three hundred horse-power capacity. 

 To start the furnace a little carefully ground and mixed lime 

 and coke (this being done by special grinding and mixing ma- 

 chinery, which forms an essential part of the plant) is thrown on 

 the bottom of the furnace, the current turned on, and the upper 

 electrode lowered until an arc is formed between it and the mix- 

 ture. The carbide soon begins to form, and new material is 

 shoveled in as the ingot is built up. The end of the pencil is kept 

 covered with about a foot of the mixture, and is gradually raised 

 by the attendant until the capacity of the furnace is reached ; 

 then the current is turned off and the furnace left to cool. This 

 constitutes the whole process, and is extremely simple and inex- 

 pensive, requiring no skilled labor and little machinery. Much 

 time has been lost at Spray in waiting for the furnace to cool, 

 which requires from four to eight hours. In the new plant of the 

 Philadelphia company at Niagara the lower electrode and the bot- 

 tom of the furnace consist of a car, which, as soon as the run is 

 finished, can be drawn out and a fresh car substituted, thus ob- 

 viating the loss of time and heat in waiting for the furnace to 

 cool. Many other improvements, including an arrangement by 

 which the mixed lime and coke are automatically fed into the 

 furnace, are expected to materially reduce the cost of manufac- 

 ture at the Niagara works. 



The proportions of lime and coke are roughly calculated by 

 means of the atomic weights involved in the reaction, but in prac- 

 tice it is found that, owing to impurities and loss in the process, 

 these amounts have to be exceeded somewhat. After the mass in 

 the furnace has cooled sufficientlj'", it is dumped on a grate which 

 holds the carbide and permits the unreduced material, amount- 



