An Electrical Furnace. 53 



same material coarsely broken, the whole being arranged in 

 a box of fire-brick, covered with perforated tiles and opened 

 at the ends to admit two carbon electrodes an inch and a 

 half in diameter. Through these, the current from a 

 dynamo-electric machine of 30 horse-power is now made to 

 traverse the central core of carbon fragments, whereby such 

 a temperature is at once produced therein that platin- 

 iridium may be instantly melted, and the most refractory 

 oxides already named are not only fused and volatilized, 

 but reduced to their elemental state, with formation of car- 

 bonic oxide gas. 



If alumina in the form of granulated corundum is mingled 

 with the carbon in the electric path, aluminium is rapidly 

 liberated, being in part carried off with the escaping gas, 

 and in part condensed in the upper layer of charcoal. In 

 this way are obtained considerable masses of nearly pure 

 aluminium, and others of a crystalline compound of the 

 metal with carbon. When, however, a portion of granulated 

 copper is placed with the corundum, an alloy of the two 

 metals is obtained, which is probably formed in the over- 

 lying stratum, but, at the close of the operation, is found in 

 fused masses below. In this way, there is got, after the 

 current has passed for an hour and a half through the fur- 

 nace, from four to five pounds of an alloy containing from 

 fifteen to twenty per cent, of aluminium, and free from iron. 

 On substituting this alloy for copper, in a second operation, 

 a compound with over thirty per cent, of aluminium is 

 obtained. Already, the small experimental plant, with a 

 30 hoise-power dynamo, is producing daily over five pounds 

 of aluminium in the form of a rich and brittle alloy, which, 

 by suitable additions of copper, is converted into different 

 grades of aluminium bronze. The valuable qualities of these 

 are so well known that it is only their great cost hitherto 

 that has prevented their more general use in the arts. They 

 are now offered for sale at Cleveland on a basis of five dollars 

 a pound for the contained aluminium. 



The reduction ot silicon is even more easy than that of 

 aluminium. When siliceous sand, mixed with carbon, is 

 placed in the path of the. electric current, a part of it is 



