224 ANNUAL REPORT SMITHSONIAN INSTITUTION, 1911. 
Commercially, we are as far from being able to produce artificial 
diamonds as in the days of the alchemists. It is, perhaps, a bold 
thing to say that no such thing as an artificial diamond will ever be 
placed on the market, but one can safely assert that so far as our 
knowledge stands at present it is impracticable. In saying this, I 
am quite aware that statements as to the commercial production 
of synthetic diamonds being an accomplished fact have quite recently 
appeared broadcast in the public press, but those who are responsible 
for such statements are, shall we say, under a misapprehension as to 
the meaning generally conveyed by the term ‘‘synthetic,”’ and are 
unable to follow the distinction I have drawn between an artificial 
gem and an imitation. 
To pass on to corundum, the problem of its artificial production is 
very much simplified by the fact that its composition is oxide of 
aluminium, and alumina—which is, therefore, its amorphous equiy- 
alent—fuses to a liquid under ordinary atmospheric pressure at a 
temperature somewhere about 2,000° C. (the exact point has not as 
yet been determined), and being the only stable oxide of a strongly 
basic metal, it can be heated in air without any change. 
The chief problem to be faced, therefore, is that of attaining the 
necessary temperature, and it is not surprising that crystalline 
alumina was produced as a scientific curiosity as far back as the 
commencement of the nineteenth century. It is at this time that we 
first begin to hear of the oxy-hydrogen blowpipe (or the gas blow- 
pipe as it was then called), and in a book published in 1819,! describ- 
ing various experiments with this new apparatus, we read that 
“two rubies were placed upon charcoal and exposed to the flame 
of the gas blowpipe * * * after suffering it to become cold 
* * * the two rubies were melted into one bead.” This hint 
does not appear to have been followed up for some considerable time, 
however, and the earlier experimenters in the production of artificial 
gems worked in another direction; they were unable to obtain 
products of commercial utility, because although they succeeded 
in obtaining crystalline alumina, it was produced under conditions 
which resulted in the formation of a mass of small crystals, almost 
microscopic in size. Moreover, the form of these crystals was that 
of the hexagonal plate which is the fundamental form of corundum, 
and such a form would be useless for cutting even when of consider- 
able area, owing to its thinness. Thus Gaudin, who appears to have 
been one of the first to attain any success in this direction, obtained 
a mass of such crystals by fusing alum and potassium sulphate in a 
closed crucible. Ebelman obtained similar results by fusing alumina 
with borax, and later Deville and Caron used aluminum fluoride 
and boric acid. All these attempts yielded similar results, as in each 
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1 The Gas Blowpipe, by Dr. E. D. Clarke. 
