118 BEITISH ASSOCIATION FOB THE 



and by the expiration of the 15 or 20 minutes before nanied, that part of the car- 

 bon -which appears mechanically mixed and diffused through the crude iron has 

 been entirely consumed. The temperature, however, is so high that the chemi" , 

 cally-combiued carbon uow begins to separate from the metal, as is at once indi- 

 cated by an immense increase in the volume of flame rushing out of the throat o 1 

 the vessel. The metal in the vessel now rises several inches above its natural level' 

 and a light frothy slag makes its appearance, and is thrown out in large foam-like 

 masses. This violent eruption of cinder generally lasts five or six minutes, when 

 all further appearance of it ceases — a steady and powerful flame replacing the 

 shower of sparks and cinder which always accompanies the boil. The rapid union 

 of carbon and oxygen which thus takes place adds still further to the temperature 

 of the metal, while the diminished quantity of carbon present allows a portion of 

 the oxygen to combine with the iron, which undergoes combustion, and is convert- 

 ed into an oxide. At the excessive temperature that the metal has now acquir- 

 ed, the oxide, as soon as formed, undergoes fusion, and forms a powerful solvent 

 of those eartby bases that are associated with the iron. The violent ebullition 

 which is going on mixes most intimately with scoria? and metal, every part of 

 which is thus brought into contact with the fluid, which will thus wash and cleanse 

 the metal most thoroughly from the silica and other earthy bases which are com- 

 bined with the crude iron, while the sulphur and other volatile matters which 

 cling so tenaciously to iron at ordinary temperatures are drawn off, the sulphur 

 combining with the oxygen, and forming sulphurous acid gas. The loss in weight 

 of crude iron during its conversion into an ingot of malleable iron, "was found, on 

 a mean of four experiments, to be 12^ percent., to which will have to be added 

 the loss of metal in the finishing rolls. This will make the entire loss probably 

 not less than 18 per cent., instead of about 28 per cent., which is the loss on the 

 present system. A large portion of this metal is, however, recoverable, by treat- 

 ing with carbonaceous gases the rich oxides thrown out of the furnace during the 

 boil. These slags are found to contain innumerable small grains of metallic iron, 

 which are mechanically held in suspension in the slags, and may be easily recov- 

 ered, by opening the tap-hole of the converting vessel, and allowing the fluid mal- 

 leable iron to flow into the iron ingot moulds placed there to receive it. The 

 masses of iron thus formed will be perfectly free from any admixture of cinder, 

 oxide, or other extraneous matters, and will be far more pure and in a sounder 

 state of manufacture than a pile formed of ordinary puddle bars. And thus it will 

 be seen that by a single process, requiring no manipulation or particular skill, and 

 with only one workman, from three to five tons of crude iron passes into the con- 

 dition of several piles of malleable iron in from thirty to thirty-five minutes, with 

 the expenditure of about one-third part the blast now used in a fiery furnace with 

 an equal charge of irou, and with the consumption of no other fuel than is con" 

 tained in the crude iron. To persons conversant with the manufacture of iron 

 /■said Mr. Bessamer), it will be at once apparent that the ingots of malleable metal 

 which I have described will have no hard or steely parts, such as are found in 

 puddled iron, requiring a great amount of rolling to blwid them with the general 

 mass ; nor will such ingots require an excess of rolling to expel cinder from the 

 interior of the mass, since none can exist in the ingot, which is pure and perfectly 

 homogeneous throughout, and hence requires only as much rolling as is necessary 

 for the developemeut of fibre ; it therefore follows that, instead of forming a mer- 

 chant bar or rail by the union of a number of separate pieces welded together, it 



