Sir
William Crookes attributes the possibility of making artificial
diamonds to the facilities afforded by the enormously high
temperatures which have been obtainable only in recent years by the use
of electricity. While electricity has, no doubt, played an important
part in the scientific researches during the last decades of the
nineteenth century, Mr. Hannay's experiments would indicate that it is
not absolutely essential to have extremely high temperatures or
pressures in order to produce artificial diamonds. Still Sir William
Crookes shows that by means of these high temperatures substances such
as carbon obey the common laws which govern other substances, and can
be made volatile and fusible under certain conditions. He has
demonstrated that the temperature necessary to volatilize pure carbon
is about 3,600° C, and that it passes into the gaseous state without
liquefying. He infers that, if, however, sufficient pressure were
applied with the high temperature, liquid carbon would be produced
which upon cooling would crystallize in diamonds. In making this
product the absence of oxygen is absolutely necessary since carbon at
high temperatures is chemically most energetic, and if it can possibly
get at oxygen from the atmosphere or from any compound containing
oxygen it will combine with it and fly off in the form of carbon
dioxide. Heat and pressure, therefore, are of no value unless the
carbon can be kept inert.
Sir
William Crookes went through the process of producing diamonds before
the eyes of his audience, but was able to show them the result of his
experiment only by pro-
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