Omaha daily bee., 1895-11-10
CUSTOMERS:

curious furnaces, each of which measures
about fifteen feet long, seven feet wide, and
six feet high. In the center of each end
wall of the furnace is a large bronze plate,
to which are connected four large copper
cables. These cables serve to convey the
current, which is supplied from the trans
former room to the furnace building by mas.
sive copper bars laid beneath the floor. Con
nected with the inner surface OF each of the
large plates are sixty carbon rods, each oil
which is about two feet long and three inches
in diameter The rods project through the
walls of the furnace and form the terminals
When the furnace has been built up in this
way the mixture Is introduced into it, about
ten tons constituting a charge
Through the center OF the mixture a
core formed of small grains of coke is built
and serves to make a continuous electrical
connection between the two terminals. Wher
the current is turned on it traverses this core
and presently raises it to an enormou tenn
p~erature, at which the chemical change that
produces carborundum takes place. The cur
rent is kept on for about twenty-fOur hours
and then the furnace is allowed to cool down
When the furnace is opened ii presents a
very beautiful appearance. Round the core
is a ring of beautiful crystals varying in color
from yellow to violet. These crystals are car,
borundum. 1t is also observed that the coke
core has changed in appearance, for 1t now
has a somewhat metallic lustre, and If a
piece be pressed between the fingers 1T is
found to be quite soft and makes a mark
like black lead. At the enormous tempera-
ture of the electric furnace all impurities
have been driven off from the coke and a
very pure form Of carbon remains. The crys-
tails are removed from the furnace and car
ried to a mill, where they are crushed to a
fine powder. They are then treated with sui
phuric acid, washed, sifted and stored away.
On last Tuesday an experimental furnace
Of a new form was fired and kept running
,,,Nl UIYtrg1uNr Ohio ~ NrQ Hnnln1 and
opened. The yield was estimated at some
thing over / 900 pounds of crystals that were
simply remarkable for their size and beauty.
Some groups showed magnificent black crys-
tails three-quarters Of an inch long; the
largest ever produced at Monongahela were
never known to exceed one-quarter Of an
inch.
1t appears further that by lengthening the
new style of furnace somewhat crystals Of
better color than any yet produced will be
obtained, while the expense OF the process is
materially reduced.
Today the workmen are erecting a fur
mace according to the new plans, the distance
between the carbOns being twelve feet nine
inches, and the output will be waited for
with great interest.
About two tons OF carborundum are OBJ
tanned from the furnaces hitherto used after
a run Of twenty-four hours, thus involving
an expenditure of energy OF $4,000 horse
power hours, which would indicate that the
material obtained must be of great value.
Until the invention Of carborundum men have
employed certain very hard minerals, such
as emery and corundum, as abrasives. The
utilization OF these minerals has proved OF
the greatest value in various manufactures
Hundreds of workmsn are employed
throughout the world in obtain
ing these minerals. Their value lies
in their hardness, for the harder they are the
more time and labor they save in grinding
away q given amount of material. Now the
saving Of labor and time by the u9e OF emery
in this way pays many time over for its orig
inal cost. If, then, a material much harder
than emery could be obtained, 1t would be
much more valuable, and carbOrundum is this
material. The great hardness Of carborundum
is well illustrated by the story Of one Of Mr.,
Acheson's early experiments.
II made the first test In diamond cutting
with carborundum myself" said Mr.. Acheson.
lathe and charged the surface with fine car
borundum crystals. l then pressed a diamond
ring against the revolving disk, and in four
or five minutes the face, which had been
pressed against the disk, was found to be
devoid Of lustre, OF a milky color, and scored
with lines. The second test was made In a
diamond polishing establishment in New York.
My experiment was satisfactory in its way
but my diamond did not look nice, and
wanted 1t to be repolished. | therefore asked
the proprietor Of the diamond polishing works
to polish the diamond using carborundum
| power instead OF diamond dust. lie consented
10 do this under certain conditions, a new
lap was to be used, free from all diamond
powder; my material would be tried hrst,