Electrical products Blumfnum. 225 



proper voltage and secondly to change it from 

 an alternating to a direct current. These 

 iron vats or crucibles are connected up in 

 series, electrically, and then they are filled 

 \vitli the alumina and certain other materials, 

 which act either as a flux or as a means of in- 

 creasing the conductivity of the mixture ; just 

 what this substance is, is probably one of the 

 secrets of the process. When all of the cruci- 

 bles are filled with the mixture the current is 

 turned on and is kept on continuously night 

 and day seven days in the week. All of the 

 material in the different crucibles is heated to 

 redness, when the process of separation takes 

 place. The oxygen of the alumina is thrown 

 off as a gas, and other residuum floats to the 

 top of the crucible and is skimmed off. 



Metallic aluminum in a melted state sinks 

 to the bottom of the crucible, where it is 

 dipped out from time to time with large iron 

 ladles and poured into sand and molded into 

 I >!<>eks similar to that of pig iron. From time 

 i<> time, JK the metal is dipped out, fresh 

 alumina with the other substances are thrown 

 in on top of the crucible, so that the process is 

 continually ^oinL r on, day and night, week in 

 and week out. The heat in the process of re- 

 ducing alumina, as we have before seen, is not 

 the chief factor: it -imply serves to reduce the 

 compound to a fluid state so that the elec- 

 trolytic action can readily take place. 



