298 THE SCIENTIFIC PAPERS Ofr 



IEISH BAUXITE. 



Raw. Calcined. 



A1 2 3 . . . 35-0 44-58 



Si0 2 . . .3-5 4-45 



Ti0 2 . . . . 2-0 2-54 



Fe 2 3 . . . 38-0 48-40 

 H 2 .... 21-5 



The complete rotary furnace, such as is now ill use at Messrs. 

 Vickers and Co.'s, at Sheffield, and at my Sample Steel Works at 

 Birmingham, consists of a set of four regenerators of the usual 

 construction with reversing valves and gas-producers. The 

 rotative chamber is constructed of iron, and rests upon four anti- 

 friction rollers. Wheel-gearing is applied by which either a very 

 slow rotative velocity of from four to five revolutions per hour can 

 be imparted to the chamber, or a more rapid velocity of about 

 60 to 80 revolutions per hour. The chamber is about 7' 6" 

 in diameter and 9' 0" long, and is provided with a Bauxite 

 lining about 7" thick. A tap-hole is on the working side for dis- 

 charging the slag into the cave below, where it is received in 

 vessels mounted on wheels. At the two extremities of the cylin- 

 drical rotative chamber with its truncated ends, are large orifices, 

 one of which, on the side of the regenerators, serves for the in- 

 troduction of the heated gas and air as well as for the exit of 

 the products of combustion, and the other facing the work- 

 ing platform is closed by a stationary door hung before it in the 

 usual manner. Although the passage for the introduction of the 

 gases in combustion is separated only by a vertical partition wall 

 from the passage through which the products of combustion are led 

 away, the chamber is heated very perfectly, care only being taken 

 that the gases enter the chamber with a certain velocity, which 

 sends them forward towards the door and makes them reach the 

 exit passage only after having traversed the rotative chamber to 

 and fro. 



This rotative furnace is worked as follows : 



The ore to be smelted is broken up into fragments not exceed- 

 ing the size of peas or beans ; to it is added lime or other fluxing 

 material in such a proportion that the gangue contained in the ore 

 and flux combines with only a little protoxide of iron into basic 

 and fluid slag. If the ore is hematite, or contains silica, I prefer 



