crystals, the film is far more intense, and snow-white. This I found
later to be merely an effect of the bright surface of the crystals,
for when an aluminium electrode was highly polished it exhibited more
or less the same phenomenon. I made a number of experiments with the
samples of crystals obtained, principally because it would have been
of special interest to find that they are capable of phosphorescence,
on account of their being conducting. I could not produce
phosphorescence distinctly, but I must remark that a decisive opinion
cannot be formed until other experimenters have gone over the same
ground.

The powder behaved in some experiments as though it contained alumina,
but it did not exhibit with sufficient distinctness the red of the
latter. Its dead color brightens considerably under the molecular
impact, but I am now convinced it does not phosphoresce. Still, the
tests with the powder are not conclusive, because powdered carborundum
probably does not behave like a phosphorescent sulphide, for example,
which could be finely powdered without impairing the phosphorescence,
but rather like powdered ruby or diamond, and therefore it would be
necessary, in order to make a decisive test, to obtain it in a large
lump and polish up the surface.

If the carborundum proves useful in connection with these and similar
experiments, its chief value will be found in the production of
coatings, thin conductors, buttons, or other electrodes capable of
withstanding extremely high degrees of heat.

The production of a small electrode capable of withstanding enormous
temperatures I regard as of the greatest importance in the manufacture
of light. It would enable us to obtain, by means of currents of very