Again, if the appearance in the
daytime of the article which it is desired to have appear luminous at
night is not material, it may be left unpainted and simply sized to
retain the powder.
In printing it is probable that the composition will be employed almost
exclusively in the form of dry powder, as printing-ink, normally pasty,
becomes too thick to be well handled when it is combined with powder in
sufficient quantity to render the printed surface luminous. However, the
printed surface of a freshly printed sheet may be rendered luminous by
dusting the sheet with powder, which will adhere to all of the inked and
may be easily shaken from the unmoistened surfaces thereof.
I am aware that monosulphide of calcium and magnesia have before
been used together in phosphorescent compounds. What I claim is a
phosphorescent composition consisting of monosulphide of calcium,
combined with carbonate of lime, magnesia, and silex, substantially as
described.
Orlando Thowless, of Newark, N.J., obtained a patent for a process of
manufacturing phosphorescent substances dated November 8, 1881.
The inventor says: The object of my invention is to manufacture
phosphorescent materials of intense luminosity at low cost and little
loss of materials.
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