394 
Cast Steel . 
on account of its having absorbed a portion of carbon 
from the charcoal with which it was in contact, though this 
is by no means the only action that takes place in the pro- 
cess of steel- making, as we shall show in the next section. 
Blister steel is employed only for the coarsest purposes, 
such as pointing horses shoes, ploughs, and other agricul- 
ral instruments, &e. By being drawn down into smaller 
bars under the tilt-hammer, its texture is considerably im- 
proved, and it is known in the markets by the name of 
tilted steel . As repeated hammering improves iron, so 
it does steel : hence if a bar of highly carbonized blister 
steel, be broken into very short pieces, and these being 
formed into small packets, are again welded together and 
drawn down into bars, which being again doubled toge- 
ther are welded and tilted, repeating the process tw T o or 
three times, the result will be a very material improve- 
ment in compactness and toughness, and the metal will be 
found well qualified for swords and the larger articles 
of cutlery : this steel has long been prepared in high per- 
fection in Germany, whence it is called German steel ; it 
is also known by the name of Shear steel . 
T his is the proper place to mention the process of Case- 
hardening , which in fact is only an imperfect kind of cemen- 
tation, converting little else than the immediate surface of 
the metal into steel, and therefore being performed not on 
the rou s:h bar, but the manufactured article. The cements 
or carbonaceous substances used on this occasion are 
bone shavings or turnings, horn cuttings, and old leather 
shoes. The work intended to be cased, having been pre- 
viously filed to the requisite shape, that there may be as 
little occasion as possible to apply the file afterwards, is 
laid together with the cement in a pan of plate-iron. A forge 
fire is then made of considerable size, and when the up- 
per part has caked together it is carefully lifted off with- 
out breaking, the pan is laid upon the red coals and cover- 
ed with the caked mass. 
In this state it remains for near- 
