THE BOOK OF DIAMONDS
Several
attempts were tried to use mercury for cooling. In one case the mercury
was thrown on the red hot fused liquid. There was a violent explosion.
Small hot metallic shots formed and flew all over the room. In another
instance the fused mass was poured on top of the mercury. In this case
very little explosion occurred. Diamonds were not formed in either
case. Many other methods of cooling have been tried, but none has been
as effective as the ice-brine solution.
It
appears that it is not the extremely low temperature of the cooling
agent, but the rate of change of the temperature of the molten iron
that determines the pressure and the inner contraction of the iron and
carbon mixture and forms diamonds.
In
all of the above experiments alternating current was used. The heating
was conducted as follows:— A mixture of chemically pure iron filings
and starch carbon was heated in the furnace for one hour and fifteen
minutes. The current used was 70 volts and 150 amperes.
On
April 21, 1937, a direct current was supplied from the electric welder
at the Churchill Boiler Works of Mc-Pherson. It was used in an
experiment made in June, 1937. The procedure for this experiment was
much like that for the one above excepting that in this case 100 volts
and 250 amperes were used. An arc was struck between a carbon electrode
in the welding holder and the surface of the mixture in the crucible.
In the first case no diamonds were apparently made and in the second
case very small crystals
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