Pittsburg dispatch. [volume] (Pittsburg [Pa.]) 1880-1923, 1892-05-15

beyond question. The discovery of q ma
| terial which meets the requirements on
! which such important and far-reaching is.
sues depend is destined to mark an epoch In
the history of electric lighting.
| Tho Qualities Of Carborundum.
Thus, much Of the electrical utilization OF
| the new product to which universal stten-
| tion has been drawn by the distinction con-
| ferred upon it by Tesla's investigation into
the nature and qualities Of this Interesting
material lead to the belief that eventually
its greatest utilization will be in industries
other than electrical. It's later form has
the appearance of greenish-yellow, glisten-
| ing cindery mass. Under the microscope
some are green, others yellow, blue or black,
and the refractive power Of the whole is 50
great that the substance is of dazzling
beauty. Its general formation is somewhat
irregular, more or less resembling bort, or
diamond powder, and the facets of its
crystals are, ss rule, convex.
Its characteristics are extreme hardness,
retroactive power, insolubility and infusibil-
ity, and especially its high abrasive power
Its manufacture is in such an early stage
that it is impossible yet to say where its
tionably, however, be in demand by diamond
cutters, lapidaries and jewellers, dentists,
valvegrinders, and for brass and optical
work; in fact in all industries where abrad-
ers are used in the form of either diamond
powder or emery. The cost of Its produc-
tion is so low that the manufacturing in
dustries will find themselves supplied with
an abrasive material of the hardness of dia-
mond powder, and the general adaptability
of emery powder, at a price relatively but
little higher than that Of emery, and practi-
cally much less.
1t Beats Emery Easily.
A very interesting and conclusive test of
its relative abrading power was made before
the writer. On the end of one of two strips
of glass, about inch wide by 21S inches
powder, which had been moistened with
water. The second piece of glass was then
superposed on the first and at given signal
the two were vigorously rubbed together
under pressure for Is seconds The emery
was then washed off, and corresponding
quantity of carborundum powder of the
same degree of fineness was placed on the
other end Of the glass, and the test was re-
peated for the same space of time. The diff
ference in the sound of the action of the
two powders was at once apparent, the car
borundum seeming to have at least twice
the grip of the emery. On looking at the
record of the respective work on the glass,
this impression was more than verified: the
emery had made a slight irregular cloudiness
on the glass, but the carborundum had rem
dered it opaque and had cut well-defned
path across it. The cut only hints at the
effect produced.
The crystals of carborundum are so hard
that it is found impossible to reduce them
to powder by any grinding process, SO a
crushing force, such as is obtained in a
stamping, mill is resorted to- To grade off
the powder in the different degrees of fine
ness, the crushed product is mixed with
water and permitted to float for any re-
quired length of time, and then run off and
allowed to settle in tanks. The coarseness
or fneness of the powder is determined by
the length of time allowed before running
off,
win supplant the Emery Wheels.
In this way the grading can be most ac-
,urately effected. The time allowed varies
rom four minutes in the coarse grades to
,wo hours for the exceedingly fine ones:
The crude material is made directly into !
wheels for machine shops. The abrading /
power of these wheels, Judging by tests
ately made, will bring them Immediately |
nto active competition with emery wheels |
)ne of our prominent manufacturers, in |
discussing recently the chances of success |
ul rivalry with emery said: 'The field is
arge, Pittsburg alone uses $50, 900 of emery |
wheels yearly, and the annual consumption |
# these wheels throughout the United |
states is at least 81, 5000 000."
The economy of carborundum will be seen |
n the fact that it will do 25 per cent more
work in the same length of time, and the |