| for eight or ten days. 
336 
STEARINE. 
STEARINE. The constituent of oils’ and fats 
which is solid at common temperatures. See the 
article Ort. 
STEEL. Thehard carburet of iron; that is to 
say, a compound of iron and carbon. Its discovery 
was antecedent to the origin of authentic history. 
Pliny says that, in his time, the best steel came 
from China, and the next best from Parthia. 
A manufacture of it existed in Sweden as early 
as 1340; but it is the general opinion that the 
process for converting iron into steel, called ce- 
mentation, originated in England. The furnace 
in which iron is converted into steel, has the 
form of a large oven, or arch, terminating in a 
vent at the top. The floor of this oven is flat 
and level. Immediately under it there is a large 
arched fire-place, with grates, which runs quite 
across from one side to the other, so as to have 
two doors for putting in the fuel from the outside 
of the building. A number of vents, or flues, pass 
from the fire-place to different parts of the floor of 
the oven, and throw up their flame into it, so as 
to heat all parts of it equally. In the oven itself, 
there are two large and long cases or boxes, 
built of good fire stone; and in these boxes the 
bars of iron are regularly stratified with char- 
coal powder, ten or twelve tons of iron being put 
in at once, and the box is covered on the top 
with a bed of sand. The heat is kept up, so 
that the boxes and all their contents are red hot 
A bar is then drawn out 
and examined; and if it be found then suffi- 
ciently converted into steel, the fire is withdrawn 
and the oven allowed to cool. This process is 
called cementation. The bars of steel formed in 
this way are raised, in many parts, into small 
blisters, obviously by a gas evolved in the inte- 
rior of the bar, which had pushed up, by its elas- 
ticity, a film of the metal. On this account, the 
steel made by this process is usually called 6b/is- 
tered steel. The bars of blistered steel are heated 
to redness, and drawn out into smaller bars by 
means of a hammer, driven by water or steam, 
and striking with great rapidity. This hammer 
is called a t2lting hammer, on which account, the 
small bars formed by it are called ¢zlted steel. 
When the bars are broken in pieces and welded 
repeatedly, and then drawn out into bars, they 
acquire the name of German or shear steel. Steel 
of cementation, however carefully made, is never 
quite equable in its texture; but it is rendered 
quite so by fusing it in a crucible, and then cast- 
ing it into bars. Thus treated, it is called cast- 
steel, and sells at a much higher price than com- 
mon steel. The process was contrived at Sheffield 
in 1750, and for a long time kept secret. When 
steel is to be cast, it is made by cementation in 
the usual way, only the process is carried some- 
what farther, so as to give the steel a whiter 
colour. It is then broken into small pieces, and 
| put into a crucible of excellent fire-clay, after 
which the mouth of the crucible is filled up with 
vitrefiable sand, to prevent the steel from being 
STEEL. ae 
oxidized by the action of theair. The crucible | 
is exposed for five or six hours to the most in- || 
tense heat that can be raised, by which the steel 
is brought into a state of perfect fusion. It is 
then cast into parallelopipeds about a foot and a 
half in length. To fuse one ton of steel, about 
twenty tons of coals are expended; which ac- 
counts for the high price of cast-steel, when 
compared with that of iron, or even of common 
steel. very time that cast-steel is melted, it 
loses some of its characteristic properties; and 
two or three fusions render it quite useless for 
the purposes for which it is intended. It has 
recently been proved that the steel of which the 
Damascus blades were made, and which was 
steel from Golconda, owed the peculiarity which 
these blades have of showing a curious waving 
texture on the surface, when treated with a 
dilute acid, to their consisting of two different 
compounds of iron and carbon, which have sepa- 
rated during the cooling. It is cast-steel in 
which the process is carried farther than usual, 
and which is cooled slowly; both common steel 
and cast-steel are formed, which separate during 
the slow cooling. The steel is rendered black 
by the acid, while the cast-iron remains white. 
This kind of steel can only be hammered at a 
heat above that of cherry-red. The specific gra- 
vity of good blistered steel is 7°823. When this 
steel is heated to redness, and suddenly plunged 
into cold water, its specific gravity is reduced to 
7747. The specific gravity of a piece of cast- 
steel, while soft, is 7°82; but when hardened by 
heating it red-hot, and plunging it into cold 
water, it ig reduced to 7°7532. Hence it ap- 
pears, that when steel is hardened, its bulk in- 
creases. The colour of steel is whiter than that 
of iron. Its texture is granular, and not hackly, 
like that of iron. The fracture is whitish-grey, 
and much smoother than the fracture of iron. 
It is much harder and more rigid than iron; nor 
can it be so much softened by heat without los- 
ing its tenacity and flying in pieces under the 
hammer. It requires more attention to forge it 
well, than to forge iron; yet it is by its tough- 
ness and capability of being drawn out into bars, 
that good steel is distinguished from bad. Steel 
is more readily broken by bending it than iron. 
If it be heated to redness, and then plunged into 
cold water, it becomes exceedingly hard, so as to 
be able to cut or make an impression upon most 
other bodies. But, when iron is treated in the 
same way, its hardness is not in the least in- 
creased. When a drop of nitric acid is let fall 
upon a smooth surface of steel, and allowed to 
remain on it for a few minutes, and then washed | 
off with water, it leaves a black spot; whereas 
the spot left by nitric acid on iron, is whitish- 
green. Steel is not so easily converted into a 
magnet as iron; but, when once converted, it 
retains its magnetic properties much longer. 
Numerous investigations have, at different pe- 
riods, been made concerning the composition of 
--— 
