escape. This fraud, one of the most daring recorded in
history, excited public interest throughout Europe, and caused
a decline in the use of the diamond in France ; and during
the Revolution, which soon followed, it was entirely ignored.
Artificial Diamonds.— Attempts have been made to produce
these gems by an artificial process, but thus far the efforts
have not been attended with very gratifying results. M. Despretz, after repeated experiments made in 1828, succeeded in
obtaining some minute crystals resembling diamonds, which,
however, were regarded as failures.* These abortive results
did not deter sanguine experimenters from making further
attempts to discover a method of manufacturing diamonds, or a
production so closely resembling them as to replace the
genuine article, from boron, one of the elementary substances,
which closely resembles carbon, the constituent of the diamond, in several of its properties, while its transparency, power
of refraction, hardness, play of colors, and resistance to the
action of nearly all chemicals, render it a desirable substance
from which a gem of such excellence as to compete with the
diamond might be artificially formed.
On the other hand, it must be stated that boron crystals are
very difficult to be obtained, and when secured, they have been
thus far only of very small size. Glass imitations are produced
with much greater facility, and they closely resemble the
genuine diamond in brilliancy and prismatic effect, though they
*/At a meeting of the Royal Society in 1879, a paper was read by Mr. Hanny,
entitled " On the Solubility of Solids in Gases," which stated some interesting
experiments relating to this subject. It was shown that a crystal of potassic
iodide could be dissolved in alcohol gas, and become again crystallized. The
experiment was successfully tried with various solids. This suggested the idea
that if some gaseous solvent could be found to dissolve carbon, artificial diamonds
could be produced. Mr. Hanny succeeded in finding such a solvent, and obtained
some minute crystals containing 97 per cent of carbon, and with all the attributes of
natural diamonds.
