|
ARTIFICIAL PRODUCTION OF DIAMOND
|
223
|
||
|
|
|||
|
Other experiments
The
action of water on carbide of calcium, and of concentrated sulphuric
acid on sugar for 6 hours under pressure of 30,000 atmospheres, was
tried; in both cases amorphous carbon was formed and no diamond.
Hannay's
experiments were repeated, where paraffin and Dippel's oil with the
alkali metals, especially potassium, were sealed in steel tubes and
subjected to a red heat for several hours. The analysis gave no
diamonds; in fact it became apparent that when hydrocarbons or water
were relied on to produce pressure, the latter could only exist for a
short time at the commencement, for when a red heat was reached the
hydrogen escaped through the metal, and the oxygen combined with the
steel.
We
did not analyse the steel tubes themselves. Many experiments were,
however, tried with central heating under the press at 6000
atmospheres, and nothing was obtained of interest with the substances
used by Hannay, unless, as previously mentioned, some iron was present.
Priedlander's experiment was repeated, where a molten globule of
olivine, in a reducing flame, or with carbon added, was stated by him
to contain minute diamonds. An experiment was made with molten olivine
in a carbon crucible in a wind furnace stirred with a carbon rod, with
and without an electric current passing between the rod and crucible.
Many
experiments were also tried at 6000 atmospheres under the press with
central heating with olivine associated with carbon, hydrocarbons,
bisulphide of carbon, water, etc., also with blue ground from Kimberley
instead of olivine. The results of the analyses were in all cases
negative, except occasionally when metallic iron was present. Thus in
some cases the olivine or blue ground was partially smelted by the
heating carbon rod or by the associated hydrocarbons, etc., when such
were added, and iron globules were formed. In these, diamond was
occasionally found when cooling was rapid and they were centrally
situated in the charge.
Very quick cooling. To
test the action of very quick cooling a carbon crucible of 2 inch
internal diameter charged with iron, sugar carbon, 2 per cent, silicide
of carbon, well boiled by resistance heating under atmospheric pressure
and 2 per cent, of iron sulphide added, was quickly placed on asbestos
mill-board resting on a steel table frictionally held in the bore of
the 4-inch mould, below being placed 2 lb. of carbon dioxide snow, and
the plunger quickly brought down by the press, subjecting the whole to
6000 atmospheres pressure. When taken out the crucible was intact, the
contents had divided into a lower portion consisting of a large grained
crumbling mass of graphite admixed with granules of very hard iron, in
the centre a rounded pillar of white iron equally hard. The cooling
seemed to have been unusually rapid.
|
|||
|
|
|||