STEEL, AND THE BESSEMER PROCESS. 211 
Puddled steel, so called, is high wrought -iron. It is wrought-iron puddled 
in the ordinary way, except that the process is stopped before the 
product is quite decarbonised. And the process produces not only the 
ordinary defects of wrought-iron in the usual degree, but the defect of 
want of uniformity in a much higher degree. It is not easy to guess at 
a minute chemioal quantity through the flame of a puddling furnace. 
Puddled steel, however, is stronger than wrought-iron. 
Crucible steel or pot steel is made from-cast iron by making cast- 
iron into wrought-iron — i. e., entirely decarbonising it by the puddling 
or charcoal refining process, and then melting the wrought-iron with 
carbon in crucibles, to recarbonise it to the proper degree. Or, wrought- 
iron bars are covered with charcoal and baked for some days in a con- 
verting oven. By this process the bars are somewhat carbonised, but 
still possess the structural defects of wrought-iron. The product, called 
blister steel, is used in this state for the cheaper kind of springs, &c; 
but its chief value is for remelting in the crucible, with additional 
carbon, to form cast-steel. Crucible steel is also made from scrap Besse- 
mer steel — the spillings from ladles, &c, and ingot and bar ends ; also 
from cast-iron decarbonised to the required degree in the Bessemer con- 
verting vessel, and then poured into water. The product is fine shot of 
perfectly uniform steel, which are remelted with or without additional 
carbon. The Bessemer process, in addition to making ingots, thus 
furnishes, directly and indirectly, the material for a large quantity of 
the best tool steel as well as low crucible steel now produced in Sheffield. 
A little manganese, or some substitute for that metal, is always put 
into the crucible with the carbon. Chemists do not agree as to the 
precise chemical office of the manganese or its substitutes ; but the 
result is to increase the ductility of the steel, in both the heated and the 
cold state. 
Bessemer steel is just as much cast-steel, both structurally and 
chemically, as steel made in crucibles ; because it is poured from a 
melted state into masses of any size, and because it is definitely and 
uniformly carbonised. 
By the Bessemer process steel is made in two ways from cast-iron. 
1st. As in Sweden, by blowing air through melted cast-iron, the oxygen of 
the air uniting with the carbon in the cast-iron, and so removing all but 
the amount required in steel, say one-half to one-tenth of one per cent. 
The oxygen also removes all but a trace of the silex, and the other 
impurities are burned out. By this process a certain definite number of 
cubic feet of air are blown through a certain weight of iron, and the 
blowing is stopped before the iron is quite decarbonised. 2nd. By the 
Bessemer process it is more usual and more convenient to blow the air 
through the melted cast-iron until all the carbon and silex are removed, 
after which a small amount of melted crude cast-iron is mixed with the 
decarbonised metal, thus giving it the proper quantity of carbon, silex, and 
manganese ; or, instead of cast-iron, artificial mixtures, containing carbon 
VOL. VI. y 
