PROGRESS IN THE MANUFACTURE OF STEEL. 809 



coal is added, while the coal on the other side having been rammed 

 down firm, ore is added, so as to fill that part of the furnace ; on this 

 is jjlaced moistened charcoal-dust, except at the top. A good blast is 

 then turned on, and, if the whole is in proper order, jets of blue flame 

 at once issue from the uncovered portion of the ore. 



During the whole of the process, at short intervals, greillade 

 and charcoal are added, and well moistened with water, to prevent 

 too rapid combustion. After about two hours from the commence- 

 ment, the wall of mine, i. e. ore in lumps is pushed well forward 

 under the tuyere, and more mine is thrown into the space thus 

 made ; this part of the process is also subsequently repeated at inter- 

 vals, until sufficient has been added to form a lump of iron or ?nasse 

 of the required size. From time to time slag is removed by opening 

 the tap-hole. At the completion of the process, a mass of metal is 

 obtained weighing about three hundred- weight, which invariably con- 

 sists partly of soft iron, and partly of steely iron and steel. 



The ore on one side of the furnace being in lumps, the hot carbonic 

 oxide generated by the action of the blast on the charcoal is able to 

 pass freely through its mass, reducing it, after the water has been 

 driven off by heat, to metallic iron. At the same time the ore becomes 

 impregnated with carbon, derived from the decomposition of the gases 

 with which it is charged. The greillade on the other side is much 

 richer in silica than the larger pieces, and from this it results that the 

 quantity of slag will vary with the greillade added. It is always very 

 rich in oxide of iron. It appears that in this process, carburized iron 

 is produced by the gradual reduction and fusion of the lumps of ore, 

 and this, coming in contact at the bottom of the furnace with slag, 

 very rich in oxide of iron, the carbon of the one combines with the 

 oxygen of the other, and the result is that iron containing more 

 or less carbon is produced, according as much or little oxide was 

 present. 



In order that steel may be produced by this process, every precau- 

 tion is taken to cause as much carburization as possible ; the unavoid- 

 able presence of oxide of iron in the slag, and the low temperature, 

 effectually preventing the formation of cast-iron ; the former, indeed, 

 making it very difficult to obtain steel. 



Rightly looked at, this process explains how steel was first ob- 

 tained, and what the essential conditions are in its production. When, 

 owing to the increased size of blast-furnaces, and the consequent in- 

 crease of temperature, cast-iron became the only product, it naturally 

 followed that this substance should be treated with a view to the 

 production of steel. This was first effected in the refining hearth, and 

 formed an important industry in Styria, Carinthia, the Tyrol, and 

 other places, in some of which it is still carried on. The operation 

 was conducted in a finery, similar in construction to those employed 

 in the production of iron in fact, iron and steel are often produced 



