394 THE SCIENTIFIC PAPERS OF 



left free for access, and is provided with a charging and discharging 

 door placed eccentrically, for the convenience of withdrawing 

 masses or balls of iron from the furnace on a level with the lining 

 when the furnace is stopped with the aperture in its lowest 

 position. The lining of the furnace is made of highly aluminous 

 or bauxite bricks covered on the inside with a certain thickness of 

 iron oxide produced by melting hammer scale and rich ores in the 

 furnace, which set while the furnace is kept slowly rotating. The 

 rotation of the furnace is effected by means of a small Brother- 

 hood or other engine, and suitable gearing. 



The modus operandi is as follows : The furnace being already 

 lined and heated, a batch of ore mixed with fluxing and reducing 

 materials, in a proportion depending upon the chemical con- 

 stitution of the ore employed, is charged from an elevated platform 

 in front, the rotator being stopped for this purpose with the 

 charging orifice in its upper position. From :30 to 40 cwt. of 

 batch is thus charged, upon which the door is closed, and the 

 furnace chamber is made to rotate at the very slow rate of six or 

 eight revolutions per hour. A high temperature is produced 

 within the chamber by the combination of the gas with the highly 

 heated air from the generator, causing the mass rapidly to become 

 hot, whilst slowly rotating, so as to present continually new 

 surfaces to the heat. No chemical action takes place under these 

 circumstances until the temperature of the mass is raised to a full 

 red heat, when reaction between the carbonaceous matter and the 

 ore will take place, giving rise to the development of carbonic 

 oxide, which, meeting the heated air proceeding from the re- 

 generators, is burned, and thus adds to the heating action of the 

 flame. When this reaction has fully set in, the supply of producer 

 gas may be almost entirely stopped, and thus no sulphurous gas 

 is admitted into the furnace during this critical interval. The 

 heat now rises rapidly, and fusion of the earthy constituents of the 

 ore occurs simultaneously with a continuance of the reducing 

 action. In the course of an hour and a half after starting, the 

 charge consists of metallic iron in a more or less agglomerated 

 condition, found on analysis to be almost chemically pure, and of 

 a liquid mass of cinder containing the earthy constituents of the 

 ore and other foreign matter. The rotation of the furnace is now 

 stopped with the tapping-hole in its lowest position, and the bulk of 



