time
philosophers vainly speculated as to the nature of the diamond; first
it was considered as a mineral, consisting of silica; but Newton was
the earliest (1675) who expressed himself as to the constitution of
diamonds. He judged, from the great refraction of light, that it must
be a combustible body, and a series of experiments with it, tested
afterwards by different naturalists, proved the same to be pure carbon.
The first trial was made in ,1694, by the members of the Academy at
Florence, by whom diamonds were volatilized within the focus of a
mirror. Bergman first classified the diamond among combustible bodies,
and mentions having cut off the head of the gems.
Various
views existed in regard to the origin of the diamond : some considered
it as a secretion of a vegetable substance; others as originating from
volcanic or plutonic revolution. The Indians believe diamonds are
continually regenerating and growing to this date ; and the inhabitants
of Pharrah, in Hindostan, affirm that the quantity of diamonds by no
means decreases, but on the contrary, the soil will yield a new supply
fifteen or twenty years from the time it is exhausted.
Numerous
experiments have been instituted to produce an artificial diamond from
several substances which contain carbon, and by the application of a
high degree of heat. The late Dr. Hare, in Philadelphia, succeeded in
melting down mahogany charcoal so as to produce a metallic appearance,
by his deflagrator. Professor Silliman likewise made similar
experiments with plumbago, which produced small globules, some of which
were so transparent that they could not be distinguished from the
genuine diamond. Professor Vanuxem, who examined the globules obtained
from fused charcoal, found them to contain iron and carbon, which led
him to the conclusion that the charcoal had not undergone a real
fusion. Cagniard de Latour pretended
