900 



STEEL 



obtained. The crucible is charged three times during the day, and is then burnt through ; 

 the first charge is usually 36 Ibs. ; which requires from 3 to 4 hours to melt it ; the 



1907 



M 



L 



second charge is about 82 Ibs., which is melted in about 3 hours ; the last charge is 

 29 to 30 Ibs., which does not require more than 2 to 2 hours to become perfectly 

 melted. The consumption of coke averages 3 tons per ton of cast steel. When the 

 steel is completely fluid the crucible is drawn from the furnace, and the steel poured 

 into a cast-iron mould ; the result is an ingot, which is subsequently rolled or ham- 

 mered according to the wants of the consumer. 



Although the melting of cast steel is a simple process, yet, on the other hand, the 

 manufacture of cast steel suitable for the various wants of those who consume it re- 

 quires an extensive knowledge. 



Fig. 1907 represents the mould for making the crucibles 

 used for melting cast steel. Each manufacturer makes 'his 

 own ; M, M, is a solid block of wood let into the floor, 

 having a hole which admits a round piece of iron fixed 

 in the centre of the plug p. The material of which the 

 crucible is made consists of 22 Ibs. of fire-clay got from 

 Stannington, near Sheffield, from the neighbourhood of 

 Burton-on-Trent, or Stourbridge ; 2 Ibs. of the old 

 crucible after it has been used, ground to powder, and 

 about Ib. of ground coke. These quantities are suffi- 

 cient for one crucible of the ordinary size. This compo- 

 sition is trodden for 8 or 10 hours on a metal-floor; it 

 is then cut into pieces of 26 to 28 Ibs. ; each piece is 

 rolled round nearly to the size of the mould into which 

 it is introduced, and the plug P is driven down with a 

 mallet ; the mould is furnished with a moveable bottom : when the pot is made, the 

 mould is lifted up by the two handles, and fixing the bottom on a post, the mould 

 falls, and leaves the crucible upon it. 



Cast steel may be wanted for the engraver. It may be produced apparently perfect, 

 and with a clear surface, but may be so improperly manufactured, that when the plate 

 has been engraved and has to be hardened, it is found covered with soft places. The 

 trial is even greater when the engraving is transferred by pressure to another plate. 

 It is, therefore, evident that a steel-maker must not only attend to the intrinsic quality 

 of his steel, but he has to use his judgment as regards the degree of hardness and 

 tenacity which it should possess. 



In manufacturing the commoner description of steel, particularly cast steel made 

 from English iron, black oxide of manganese may be added to the steel in the crucible, 

 and acts as a detergent. The oxygen unites with a portion of the carbon in the steel, 

 forming carbonic oxide gas, which acts upon the imperfectly metallic portions of the 

 steel used, and liberates the metal whilst the deleterious matter is taken up and 

 forms a slag with the manganese. There has been a great controversy regarding the 



