ARTIFICIAL PRECIOUS STONES. 335 
problem of the artificial production of that beautiful and 
valuable stone, the diamond, will at length be solved. 
Although not belonging strictly to the subject of the 
artificial production of precious stones, it will not, perhaps, 
be thought inappropriate to notice some experiments under- 
taken by Messrs. Deville and Wohler, which resulted in the 
discovery of a crystal strongly resembling the diamond in its 
hardness and properties, although of a different composition. 
This crystal is that of a substance called boron, which attracted 
the attention of Messrs. Deville and Wohler on account of its 
resemblance to carbon. It occurred to these gentlemen that a 
substance having such a great similarity to the element of which 
the diamond is composed would, in all probability, if crystallized, 
have some characteristics in common with that gem. They, 
therefore, set to work to find some process which would enable 
them to reduce it to the crystalline form. 
Boron is only found in nature in combination with oxygen, as 
boracic acid, and in union with soda as borax ; and it had, up 
to this time, been obtained from these combinations only in the 
form of a brownish-green powder, insoluble in water, and pos- 
sessing many of the properties of carbon. It was reserved for 
the two chemists whose names are given above to produce it in 
a form hitherto unknown, by the following process : — 
In a crucible lined with animal charcoal are placed eighty 
grains of aluminium and one hundred grains of boracic acid ; 
this crucible is then exposed for five hours to an intense heat, 
which causes a portion of the boracic acid to part with its 
oxygen to the aluminium. After it has been taken from the 
furnace and allowed to cool, it is found to contain a sort of glass 
composed of the remainder of the boracic acid and of the 
alumina formed during the process of heating, and underneath 
this a grey metallic mass sparkling with crystals. This mass 
consists merely of boron imbedded in aluminium. To separate 
the boron, the mass is plunged into boding caustic soda, which 
dissolves the aluminium, and is afterwards treated with hydro- 
chloric acid, to remove all traces of iron, and with a mixture of 
nitric and hydrofluoric acids, to get rid of any silicon that may 
have been left by the soda. After all these processes have been 
gone through, the boron remains alone. 
An examination of the boron obtained in this way shows 
what a great analogy exists between it and carbon, which, as 
every one knows, is found in three forms : uncrystallized in 
charcoal ; semi- crystallized in plumbago ; and crystallized in 
the diamond. Similarly the boron resulting from the above 
experiment is found to exist in three forms, viz. : in black 
flakes almost as hard as the diamond; in brilliant prismatic 
crystals less hard than the former variety ; and in small, beau- 
