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ARTIFICIAL PRODUCTION OF DIAMOND
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rod,
carrying a crown holder, with four 2-inch carbons which rested on the
lip of the crucible for resistance heating. An observation window was
placed at the apex of a long iron cone, projecting from the side of the
cover, which gave a good view of the crucible and its contents. The
whole of the chamber was submerged in a tank of water, up to the level
of the gland in the cover.
Iron
and iron alloys were boiled and allowed to cool slowly by radiation, or
were rapidly quenched by admitting water through a large valve from the
tank into the vacuum vessel. The iron and carbon vapour from the
boilings deposited dust and globules on the cover, and on the sides and
bottom of the chamber. A very small diamond residue generally resulted
from the small iron globules, and also from the dust, but never
anything from the ingot remaining in the crucible.
In
several experiments water was admitted, which played directly on the
crucible, the upper carbons resting on the rim prevented its upsetting
by the force of the water, and still there was no residue. In one
experiment the carbons were lifted and the charge flowed out, forming
spherules of varying size in the water. There was a very small diamond
residue from these spherules.
In
one experiment a crucible was filled with iron and carbon and closed by
a tight carbon cover, a hole bored in the side of the crucible, a
massive block of iron placed close opposite the hole and the crucible
boiled, the vacuum being under 1 mm. No crystallised residue was found
in the deposit on the iron block from this high velocity jet of vapour
of iron and carbon.
In
another experiment a powerful electromagnet was provided with poles to
give a concentrated field, and an arc struck between two carbons was
arranged to burn within this field and regulated from without by hand.
There was an iron block upon which the arc directed by the field could
play and condense its carbon vapour. The analysis gave no diamond.
It
was thought that the vapour from boiling iron saturated with carbon
might, by the action of bisulphide of carbon, cause a crystalline
deposit, but all the experiments to this end yielded no results.
Experiments under X-ray vacuum
Experiments
were made under X-ray vacuum in a new chamber of cast iron with very
thick walls to absorb the heat, exhausted through an 8-inch diameter
suction by a large molecular pump alongside, in series with a dry, high
speed, two stage, pump, 12-inch diameter pistons, and last of the
series a 3-inch + 2-inch compound Fleuss. The crucible was
resistance-heated as before (Fig. 12). No diamond was produced in any
of these experiments, except in those where iron, sand, and other
elements, with
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