300 THE SCIENTIFIC PAPERS OF 



furnace in their heated condition, and without subjecting them to 

 previous consolidation under a hammer or shingling machine. 



It is feasible, however, to push the operation within the rotator 

 to the point of obtaining cast steel. If this is intended, the relative 

 amount of carbonaceous matter is somewhat increased in the first 

 instance, so that the ball, if shingled, would be of the nature of 

 puddled steel, or contain even some carbon mechanically enclosed. 



If now, after removing the cinder by tapping, from 10 to lo 

 per cent, of ferro-manganese or spiegeleisen is thrown in, and the 

 heat within the rotator is rapidly raised by urging the influx of 

 heated gas and air from the regenerator, the metallic balls will 

 soon be seen to diminish, and presently a metallic bath only will 

 be found in the furnace, which may be tapped into moulds and 

 hammered and rolled into steel blooms or bars in the usual 

 manner. Experience alone can determine which mode of working 

 will ultimately prove the best ; but it is probable that for the 

 production of cast steel on a large scale it will always be more 

 profitable to transfer the metallic balls to a separate melting 

 furnace, a series of rotating furnaces working in concert with a 

 series of steel-melting furnaces, so as to produce charges of 5 or 

 tons of fluid steel. 



In comparing upon theoretical grounds this method of producing 

 metallic iron with the operation of the blast furnace, it will be at 

 once perceived that, whereas in the blast furnace the products of 

 combustion consist chiefly of carbonic oxide, and issue from the 

 top of the furnace at a temperature exceeding 350 C., the result 

 of combustion in the rotative furnace is carbonic acid, which 

 issues from the regenerative furnace into the chimney at a tempe- 

 rature rarely exceeding 175 C. This proves at once a great 

 possible saving of fuel in favour of the proposed method, and to 

 this saving has to be added the fuel required for converting pig 

 metal into wrought iron by the puddling process. 



It may however be asked, why the rotating surface should admit 

 of the complete combustion of carbon, whereas in the blast furnace 

 such complete combustion is, as is well known, not possible, 

 because each atom of carbonic acid formed would immediately 

 split up into two atoms of carbonic oxide, by taking up another 

 equivalent of carbon from the coke present. The following 

 explanation will serve to elucidate this point : 



