STEEL 895 



until such carbon is reduced to the quantity required for constituting steel, which is 

 about 1 per cent. ; the second method is to heat iron bars in contact with charcoal, 

 until they have absorbed that quantity of carbon which may be required. 



Steel may be classed into three kinds : 



1st. Natural steel, which is manufactured from pig-iron direct. 



2nd. Cemented or converted steel, which is produced by the carbonisation of 

 wrought iron. 



3rd. Cast-steel "which is produced by the fusion of either natural or cemented steel, 

 but principally from the latter. 



The various kinds of iron which are used for the manufacture of steel were formerly 

 imported from Sweden, Norway, and Russia ; but the high price of Swedish and other 

 steel-iron has compelled the consumers to look elsewhere for a supply of suitable iron, 

 and to offer every encouragement to English manufacturers so to improve their 

 steel-irons as to render them suitable for the production of steel. 



England now furnishes a large quantity of iron suitable for steel purposes, which 

 may be estimated at 20,000 tons per annum ; this iron is manufactured with great 

 care, often with an admixture of charcoal pig-iron, and various chemical reagents, 

 which are added at the caprice of each manufacturer. 



It is of the highest importance that the iron used for steel purposes should be as 

 pure as possible ; those irons which have long enjoyed the highest reputation are manu- 

 factured from the Dannemora ores in Sweden ; the whole of the steel-irons produced 

 in that country are smelted from the magnetic and red oxides containing usually 60 

 per cent, of metal. 



Natural or German steel is so called because it is produced direct from pig-iron, 

 the result of the fusion of the spathose iron ores alone, or in a small degree mixed 

 with. the brown oxide. This crude-iron contains 4 to 5 per cent, of carbon and 4 to 5 

 per cent, of manganese. Karsten, Hassenfratz, Marcher, and Reaumur, all advocate 

 the use of grey pig-iron for the production of steel ; indeed they distinctly state that 

 the best qualities cannot be produced without it ; they state that the object of working 

 it in the furnace is to clear away all foreign matters, but there can be no advantage 

 gained by retaining the carbon and retaining it with the iron. The theory is incor- 

 rect, although it is supported by such high authorities. Grey-iron contains the maxi- 

 mum quantity of carbon, and consequently remains for a longer time in a state of 

 fluidity than iron containing less carbon ; the metal is not only mixed up with the 

 foreign matter it may itself contain, but also that with which it may become mixed in 

 the furnace in which it is worked. This prolonged working, which is necessary in 

 order to bring highly-carbonised metal into a malleable state, increases the tendency 

 to produce silicated oxides of iron ; which mixing with the steel produced renders it 

 ' red short,' and destroys many good qualities which the pig-iron may have originally 

 possessed. In Austria, where a large quantity of natural steel is produced, the fluid 

 metal is tapped from the blast-furnace into a round hole ; water is sprinkled on the 

 surface which chills it, and thus forms a cake about half an inch thick. This is taken 

 from the surface, and the operation is again performed until the whole is formed into 

 cakes, they are then piled edgewise in a furnace, and covered with charcoal, and heated 

 to a full red heat for about 48 hours ; by this process much of the carbon is discharged. 

 These cakes are then used for producing steel in the refinery. A much superior 

 quality is thus obtained with greater economy. It appears that the most perfect plan 

 for manufacturing the steel is to free the crude nwtal as much as possible from its 

 impurities whilst in a fluid state. The furnaces used for the production of natural 

 steel are like the refineries in which charcoal-iron is produced. In all countries their 

 general construction is the same, but each has its own peculiar mode of working. We 

 find therefore, the German, the Styrian, the Carinthian, and several other distinct 

 methods, yet all producing steel from crude-iron directly, although pursuing different 

 modes of operation. These differences arise from the nature of the pig-iron each 

 country prodiices, and the peculiar habits of the workmen. These modified processes 

 do not affect the theory of the manufacture of the steel, but rather accommodate them- 

 selves to the peculiar character of the metal produced. 



Fig. 1900 shows a ground-plan of the furnace ; jig, 1901 an elevation ; nndfy. 1902 

 the form of the fire itself and the position of the metal within it. The fire, D, is 24 

 inches long and 24 inches wide ; A, A, A, are metal plates, surrounding the furnace. 



Fig. 1901 shows the elevation, usually built of stone, and braced with iron bars. 

 The fire, o, is 16 inches deep and 24 inches wide; before the tuyere, at B, a space is 

 left under the fire, to allow the damp to escape, and thus keep the bottom dry and hot. 



In fig. 1902 there are two tuyeres, but only one tuyere iron, which receives both the 

 blast nozzles, which are*so laid and directed that the current! of air cross each other, 

 as shown by the dotted lines ; the blast is kept as regular as possible, so that the fire 

 may be of one uniform heat, whatever intensity may be required. 



