December i, 1890 .] THE TROPICAL AQRIOULTURIST. 
457 
AETIFICIAL GEMS. 
Mr. Charles Bryant writes to the Standard -. — 
I notice that in a recent issue Mr. Greville 
Williams, cf the Gas Light Company, has manu- 
factured a perfect emerald from the refuse of a 
gas retort, and that he could in like manner pro- 
duce other precious stones ; but fortunately, as you 
state, the cost of producing them would be pro- 
hibitory, and this is one reason why those who 
possess jewels need not entertain the least fear 
that their gems are about to become diminished in 
value, if not absolutely worthless, by the artificial 
production of precious stones, because there is 
virtually nothing new in Mr. Williams’s discovery 
— precious stones having been artificially produced 
more than sixty years ago, and with all the ex- 
periments that have since been made by eminent 
chemists, the results have been very far from suc- 
cessful in a commercial sense. 
It may be interesting to many of your numerous 
readers to know that several kinds of precious 
stones have been actually produced by artificial 
methods, endowed with all the chemical and physical 
characters of Nature. In 1837 Gaudin produced 
rubies by beating ammonia, alum, and potash by 
means of the oxyhydrogen blow-pipe, the intense 
heat developed by this apparatus volatilising the 
potash and the alumina, then crystallising in 
rhombohedral forms identical with those of the 
natural stone, and having the same specific gravity 
and hardness. Ten years before Gaudin’s experi- 
ments Berthier produced a great number of minerals, 
such as peridot, pyroxene, &g. 
The spinel has been produced so perfectly as to 
be indistinguishable fr '.ni the natural gem, by sub- 
jecting a compound consisting of proper proportions 
of alumina, magnesia, chromium, and boracic acid 
to a high temperature for several days, and later 
experiments founded on the principle of Datbree 
and Durocher have resulted in the production of 
crystals of white, blue and red corundum, /.<?., 
colourless sapphires, blue sapphire.s, and rubies. 
Crystals of chrysoberyl I have produced by sub- 
jecting the fluorides of aluminium and glucinum to 
a very high temperature. 
Attempts have been made to produce the diamond 
artificially, but the specimens obtained have been 
so extremely small as to be of no use, and the 
results obtained do not difier much, so far as success 
goes, from those of the alchemists who sought lor 
that imaginary substance, the philosopher’s stone, 
in the hope that they could make gold out of the 
baser metals, and although the attempts at repro- 
ducing many of the precious stones have been met 
with a certain amount of success experrmentally, 
no one is likely to take upon himself the trouble 
and expense of so unprofitable a business, com- 
mercially, as producing artificial precious stones. 
Ten years have now elapsed since Mr. Hannay, 
of Glasgow, siroceeded in producing, at much cost 
and great danger, artificial diamonds, by enclosing 
a mixture of paraffin spirit and bone oil distillate 
with metallic lithium in a strong wrought iron 
tube, and exposing it to a prolonged heat in a 
reverberating furnace. The success which followed 
was undeniabN. The result was diamonds, but they 
were of such small size as to be practically worth- 
le?s, even could they have been generated by a 
cheaper process especially as it was found that 
when placed on the cutting wheel they immediately 
crumbled. At the same time, if anything is certain, 
it is that eventually by means too simple even to 
be foreseen, noble crystals of a gem still precious 
in spite of South Africa will ha manufactured in 
the laboratory, as a price so low that they and 
the prismatic pendants of the chandelier may be 
rated at much the same value. But the diamonds 
and the other precious stones came in'.o different 
categories. The one is a pure substa ice, the others 
are mixtures of various mineral matters. The 
moment that Smithson Tennant proved, nearly one 
hundred years ago, that the diamond was merely 
carbon, the crystallisation of this ekment, which 
is one of the most widely distributed in nature, 
was simply a question of chemical manipulation. 
And the processes of the arts have of late years 
undergone such vast improvements that it is im- 
possible not to believe in the eventual solution 
of the problem which in Mr. Hannay’s hand was 
only a succes d'estiiiie. But we may be well assured 
that the fortunate man who first sees the gems 
glittering in his crucible will not be in any hurry 
to take the Boyal -or any other — society into his 
confidence. Unless differently constituted from the 
rest of his species, he will utilise the victory at 
which he has arrived for his own enrichment. 
Most of the precious stones are, however, com- 
plicated mixtures of ingredients of whim’ll the 
mechanical disposition, as ii: inossagates and other 
pebbles, cannot always be exactly ascertained, while 
the preoiee percentages of the substance to which 
they owe their varied hues have often defied the 
chemist’s analysis. Thus the gem which Mr. 
Williams has modified from the refuse of the Gas 
Light Company’s retorts is composed of about 
sixty-S;veu to sixty-eight per cent of silica, fifteen 
to eighteen of alumina, twelve to fourteen of 
glucina, minute proportions of magnesia, carbon and 
carbonate of lime, while the intensely green colour 
for which the jewel is valued is be’ieve to be due 
to a slight dash of sesquioxide of chromium, though 
this tint has by some chemists been attributed to 
vegetable matter, the analyst having to proceed 
warily when dealing with such costly stuffs as 
diamonds and emeralds. We may, therefore, pre- 
sume that Mr. Williams has turned out his artificial 
emerald by skilful fusing and crystalisation of these 
ingredients. It is also permissible for us to imagine 
that in time he will simplify his process, until the 
Gas Company’s “superior six carat’’ stones set in 
fourteen carat gold will ba recommended to thirty 
dandies at a price which will defy competition, 
even though the profits from this branch of the 
businets do not add materially to the dividends of 
tile shareholders. Still as Mr. Bryant says, Mr. 
William’s experimenls, if interesting, are not in 
themselves unprecedented, except that they have 
resulted in the concoction of a gem not hitherto 
produced by the same means. For crystals of 
chrysoberyl have been turned out by subjecting the 
fluorides of aluminium and glucinum to a very high 
temperature, and early in this country Berthier 
fabricated a great many minerals, inoludicg peridot 
(chrysolite), pyroxene (augite), and others not of 
any economic importance. Colourless sapphires 
and blue sapphires are among the triumphs of the 
laboratory. But moat remarkable of all, rubies of 
escellent hardness and hue have been produced 
by a process of synthesis under the action of tire, 
though it is doubtful whether this was the means 
by which they were originally crystallised in the 
earth’s crust. As far back as 1837 Gaudin produced 
the ruby on a small scale, by exposing ammonia- 
alum to the heat of the oxyhydrogen blowpipe. 
By the in'ense heat, thus generated he obtained 
fused alumin.T, which is readily coloured by the 
addition of oxides of chromium, the crystals ap- 
pearing in the rhombohedrals and characteristic of 
the mineral, and having the same specific gravity 
and hardness. At a later date, Ebelmen arrive 1 
at much the same results by a different method. 
He dissolved alumina in boric acid at a high 
temperature, and on the cooling of the mass 
