PRECIOUS STONES.
1335
have been obtained. One of these is that of A. Ludwig, who has been able to produce such crystals from pulverized carhon heated in hydrogen on a spiral of iron wire in the eleetrie arc under a pressure of 3,100 atmospheres,a The other is announced by R. von Hatslinger,
who fuses graphite with silicates. lie prepares a mixture representing
as nearly as possible the composition of the African blue ground, ami
then introduces powdered graphite. The whole is melted in a crucible,
the process being facilitated by using metallic aluminum and magnesium
in preference to the
oxides of those metals. When the fused mass is dissolved, minute
octahedra are found, possessing the physical properties of diamond.i
Effect of Radium on the Diamond.—Sir
William Crookes delivered his notable lecture on the subject of the
diamond before the British Association for the Advancement of Science
at its Kimberley meeting in September, l905 In this lecture experiments
were described in connection with radium in contact with the diamond,
which showed that the beta rays from radium preparations had like
properties to the streams of inactive electrons in a radiant matter
tube. It was found, by exposing line colorless crystals of diamond to
radium bromide undisturbed for more than twelve months that the radium
caused the diamonds to assume a beautiful bluish color. This color is very persistent: it was affected neither by heating in strong nitric
acid nor by potassium chlorate. Furthermore, the radium had
communicated to the diamonds radio-active properties strong enough to
affect a photographic plate; and when they were heated to a. dull
redness in a dark room a faint phosphorescence spread over the stone
just before the color became visible.
Sir William Crookes also announced the results of his experiments in examining
the extreme baldness of the metal tantalum, produced by Messrs. Siemens
Brothers, of Berlin, lie found that a diamond drill making 000
revolutions per minute and continue; in operation for three days and
nights bad only produced a depression of one fourth millimeter in depth, the question being then as to which had been affected the more, the diamond or the tantalum.
Wages in the diamond-cutting industry.—For
the last two years there has been a great deal of disturbance in the
matter of the adjustment of the rates and hours of labor in the
diamond-cutting industry. The outcome for the United States has been
that in November, 1905, an eight-hour day was established, with wages
ranging from $40 to $80 per week for the various employees in the
industry. This result was brought about by the great demand for cut
material and by the fact thad the amount of cutting in the United
States has increased so rapidly within the last live or six
years that at the present time more than one-half of all the diamonds
sold in the United States have been cut here. As the high quality of the cutting
is not: (excelled in any of the foreign centers, and because of the
systematic methods in use in this country, there is a possibility of a
dill greater lercentage of the larger stones being cut here. This is
not true of the smaller stones.
CO RUNDUM GEMS.
CORUNDUM. SOUTH CAROLINA.
The first volume of the North Carolina Geological Survey reports c treats of the history of corundum mining both as an abrasive and as gem material.
