PRECIOUS STONES. 701
Rubies,
sapphires, cat's-eyes, alexandrites, etc., are the gems sought for, but
with these zircon, chrysoberyl, tourmalines, spinels, garnets, and
other gems are also obtained. It is proposed to work the streams by
means of dredges and other improved mining machinery. The properties
mentioned are in Ratnapura, Rakwanne, and Doloswella. In the district
acquired by the syndicate are several localities in the province of
Sabaragamuwa. The gems occurring here are true sapphires, rubies, and
cat's-eyes. Many valuable ones have been found, and the localities have
been worked from time immemorial.
ARTIFICIAL PRECIOUS STOXES.
Frequent
references have been made in the public press during the year 1893 to
Mr. Thomas A. Edison's experiments in producing artificial rubies and
sapphires. As so much stress is laid commercially on the success of
such attempts, inquiry was made of him by the writer as to whether his
results had been satisfactory or not. He responded as follows: "The
experiments to which you refer were given up because it was found
impossible to produce stones free from bubbles, which rendered them
useless for cutting edges." This referred to their use as points for
the phonograph, but the same objection would render them valueless as
gems.
In
reference to a statement that the Cowles Electric Smelting and Aluminum
Company is suffering an infringement on its patent for making
artificial diamonds by means of an electric furnace, Mr. Cowles, the
inventor, informs me that the statement is incorrect in so far as it
relates to the subject of artificial diamonds, they never having
produced any diamonds. , Therefore another reputed artificial diamond
discovery has been withdrawn. The Cowles brothers claim that they were
the first to put on record the direct reduction of silicon from silica
in the presence of carbon and in the absence of a base metal to alloy
with the product, and they claim that the product they secured is the
same as the substance "carborundum " (a) lately introduced as a
polishing material. In this substance the Carborundum Company has
discovered that there is carbon in combination with the silicon,
forming a carbide. They now hold a patent secured on the composition of
the carbides.
The
new composition known as carborundum is essentially a carbide of
silicon, containing silicon 6940 per cent, and carbon 30.20 per cent.
Dr. Mulhauser gives the specific gravity of green crystals as 3.22; Mr.
J. W. Richards, 3-0123. In form the crystals are hexagonal, either in
flat plates or in short, stout rhombohedral plates, varying from
one-half to 2-1/2 millimeters in diameter. This material has been used
as a high-class abrasive for wheels, dental tools, glass grinders, etc.
In
August, 1893, the writer, while examining the hardness of carborundum,
found that it readily scratched red, blue, white, pink, and yellow
a "Carborundum" by Acheson. See Journal of the Franklin Institute, June 1, 1893; and William V. Blake, Engineering and Mining Journal, September 9, 1893, pp. 270-330, September 23, 1893.
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