CHEMISTRY. 259 



which are combined with the crude iron, while the sulphur arid other volatile 

 matters which cling so tenaciously to iron at ordinary temperatures are driven 

 oft', 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 malle- 

 able iron was found on a mean of four experiments to be twelve and a half 

 per cent., to which will have to be added the loss of metal in the finishing rolls. 

 Tin's will make the entire loss probably not less than eighteen per cent., 

 instead of about twenty-eight per cent., which is the loss on the present 

 system. A large portion of this metal is. however, recoverable by treating 

 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 recovered. I have before mentioned that after the boil has taken place 

 a steady and powerful flame succeeds, which continues without any change 

 for about ten minutes, when it rapidly falls off. As soon as this diminution 

 of flame is apparent the workman will know that the process is completed, 

 and that the crude iron has been converted into pure malleable iron, which 

 he will form into ingots of any suitable size and shape by simply opening the 

 tap hole of the converting vessel, and allowing the fluid malleable 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 more forward state of 

 manufacture than a pile formed of ordinary puddle bars. 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 pass into 

 the condition 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 finery furnace with an equal charge of iron, and with the consumption of 

 no other fuel than is contained in the crude iron. To those who are best 

 acquainted with the nature of fluid iron, it may be a matter of surprise that a 

 blast of cold air forced into melted crude iron is capable of raising its tempera- 

 ture to such a degree as to retain it hi a perfect state of fluidity after it has 

 lost ah 1 its carbon, and is in the condition of malleable iron, which in the 

 In'ghest heat of our forges only becomes softened into a pasty mass. But 

 such is the excessive temperature that I am enabled to arrive at with a pro- 

 perly shaped converting vessel and a judicious distribution of the blast, that 

 I am enabled not only to retain the fluidity of the metal, but to create so much 

 surplus heat as to re-melt the crop ends, ingot runners, and other scrap that 

 is made throughout the process, and thus bring them without labor or fuel 

 into ingots of a quality equal to the rest of the charge of new metal. For 

 this purpose a small arched chamber is formed immediately over the throat 

 of the converting vessel, somewhat like the tunnel head of the blast furnace. 

 This chamber has two or more openings on the sides of it, and its floor is 

 made to slope downwards to the throat. As soon as a charge of fluid malle- 

 able iron has been drawn off from the connecting vessel, the workman will 

 take the scrap intended to be worked into the next charge, and proceed to 

 introduce the several pieces into the small chamber, piling them up around 



