338 



POPULAR SCIENCE MONTHLY. 



Walther process, which does not use electricity but depends on the 

 intense heat generated by burning acetylene under pressure. In 

 electric furnaces the formation of carbide depends simply on the heat 

 of the arc, which fuses the mixture of lime and coke. The latest im- 

 provements on the first very simple forms of furnace have secured 

 continuity of work and economy of electric energy. In the United 

 States carbide is made exclusively in the Horry furnace. This 

 furnace consists of a huge short cylinder or hollow wheel, mounted 



to revolve slowly on a hori- 

 zontal shaft. The periphery 

 of the cylinder is closed by 

 removable cast-iron slats. 

 As the cylinder is partly re- 

 volved on its axis from time 

 to time, the slats are taken 

 off from one side and re- 

 placed on the other, thus 

 leaving the top always open. 

 The cylinder is filled on one 

 side with the powdered mix- 

 ture of coke and lime. Into 

 the mixture two vertical 

 carbon electrodes project 

 downward through the open 

 top of the cylinder. As the 

 carbide is formed, the cylin- 

 der is revolved, lowering the 

 mass from the electrodes. 

 The fused carbide cools, hardens, and is broken off and removed 

 as it rises on the other side of the slowly revolving cylinder; new 

 material is constantly fed in to maintain the level around the elec- 

 trodes. The process in the Horry furnace is continuous; the fur- 

 nace can be run without arresting the cuiTent until repairs are neces- 

 sary. It is said to combine the different theoretical improvements 

 referred to, and to reduce the cost of production. The Horry fur- 

 nace is in use at Niagara Falls and at Sault Ste. Marie. At St. 

 Catherine's, Canada, Willson is using his own furnace. Abroad, 

 the older types of furnace, the "Willson, Bullier, and Heroult, are those 

 chiefly in use. 



The actual ingot of good commercial carbide is nearly pure — 

 ninety-six to ninety-nine per cent — but the ingot is surrounded by a 

 crust of carbide mixed with unchanged material, containing forty to 



NoTK. — We are indebted to the courtesy of tlic Klectrii-iil World an(] Engineer for cuts 

 showing the Horry furnace. 



IIoRRT FrRNACE, SHOWING ELECTRODES. 



