n the further processing of the ingot,
whether in the rolling mill or forge, special precautions should
be taken in the heating, in the reduction of the metal and in the
cooling.

No attempt is made to compare the relative merits of open hearth
and electric steel; results in service, day in and day out, have,
however, thoroughly established the desirability of electric steel.
Ten years of experience indicate that electric steel is equal to
crucible steel and superior to open hearth.

The rare purity of the heat derived from the electric are, combined
with definite control of the slag in a neutral atmosphere, explains
in part the superiority of electric steel. Commenting on this recently
Dr. H. M. Howe stated that "in the open hearth process you have such
atmosphere and slag conditions as you can get, and in the electric
you have such atmosphere and slag conditions as you desire."

Another type of electric furnace is shown in Figs. 7 and 8. This
is the Ludlum furnace, the illustrations showing a 10-ton size.
Figure 7 shows it in normal, or melting position, while in Fig.
8 it is tilted for pouring. In melting, the electrodes first rest
on the charge of material in the furnace. After the current is
turned on they eat their way through, nearly to the bottom. By
this time there is a pool of molten metal beneath the electrode
and the charge is melted from the bottom up so that the roof is
not exposed to the high temperature radiating from the open arc.
The electrodes in this furnace are of graphite, 9 in. in diameter
and the current consumed is about 500 kw.-hr. per ton.

[Illustration: FIG. 7.--Ludlum electric furnace.]

[Illustration: FIG. S.--The furnace tilted for pouring.]

One of the things which sometimes confuse regarding the contents
of steel is the fact that the percentage of carbon and the other
alloys are usually designated in different ways. Carbon is usually
designated by "points" and the other alloys by percentages. The
point is one ten-thousandth while 1 per cent is one one-hundredth
of the whole. In other words, "one hundred point carbon" is steel
containing 1 per cent carbon. Twenty point carbon, such as is used
for carbonizing purposes is 0.20 per cent. Tool steel varies from
one hundred to one hundred and fifty points carbon, or from 1.00
to 1.50 per cent.

Nickel, chromium, etc., are always given in per cent, as a 3.5
per cent nickel, which means exactly what it says--3-1/2 parts in
100. Bearin