The morning news. [volume] (Savannah, Ga.) 1887-1900, 1892-05-13
SOME POINTS ABOUT INKS.
Invisible Kinds for Secret Writings
Colored Inks and India Ink.
From &c Washinaton SIR.

Colored Inks and India Ink.
From the Washington Star.
It is very easy to make an invisible ink
II you wish to insure special secrecy for
your correspondence, )" said chemist to a
writer for the StGr "I on have only to do
your writing with solution sugar of lead
in pure water, adding TO the mixture q small
amount of gum arabic, so that it may flow
well from the pen. The letters traced with
this preparation are not visible when it has
become dry but when the manuscript is
held over jet of sulphuretted hydrogen gas
they come out intensely black. This gas is
the same as that generated in bad eggs, so
that one or two Of those might serve to do
the reading by. However, one may avoid
the necessity Of being tortured with I'M
pleasant odors by selecting some other
chemical for an ink.
ANOTHER PREPARATION.
"There is nothing better for the purpose
than bromide of copper, which you can
prepare for yourself by mixing one part of
bromide os potash one part of blue vitriol
and eight parts of water, adding a little
alcohol and gum arabic. Writing done in
this solution is absolutely invisible until ex-
posed to heat when it Immediately becomes
legible. Any dealer in chemical supplies
will sell you chloride of cobalt to which
you can add gum arabic. 1t makas a pink
script, which disappears when dry, be-
comes green when heated, disappears when
cold and is pink again when damp. Writing
done in rice water cannot be seen when it is
dry. but turns blue when iodine is applied
TO it. 1t was much employed during the
great mutiny in India. Invisible inks have
been suggested for postal cards.
HOW CoLORED INKS ARE MADE.
"Colored inks are made in all sorts of
ways, out of aniline dyes, dye woods and
chemicals of various kinds. Ground Brazil
wood is used for red ink campeachy wood
for purple, logwood for violet, sulphate of
indigo for blue and verdigris and cream of
tartar for green. Coal tar colors may be
employed in place of these. You can
manufacture for yourself an excellent
black writing ink by soaking pound of
bruised gals for twenty>four hours In boil
ing water. straining the liquid and adding
five ounces of sulphate of iron, three ounces
of gum arabic and few drops Of carbolic
acid. The gall fluid acts upon the sulphate
of iron, making an intense black, and the
carbolic acid is intended to keep the ink
from becoming moldy. To make copying
ink you have only to mix three pints of the
black ink with one pint of glyceriue
INDIA INK.
"The basis of India ink is IampbIack, which
Is made IN furnace specially constructed
for the purpose. Various kinds of oils and
grease are burned to produce the lampblack,
but the finest quality is obtained from pork
fat. The lampblack is subjected to a sift-
ing process through silk bags in order that
it shall be rendered as fine as possible. In
the manufacture of the ink the first step is
to melt in a pot quantity of a particu-
larry excellent glue from buffalo hides.
To this as much lampblack is added
as will compose a soft paste, which is
kneaded with the hands, a small guam
tity of pea oil being put in also. The MKT
ure Is made into fiat cakes and left to
'ripen' for while, after which it is COM
pressed in cylindrical molds. The cylinders
in which shape the product is sent to mar
ket, are dried and given final polish on
the outside by brushing them with a hard
brush impregnated with the kind of white
wax which is deposited on trees in China by
insects. A little musk or Borneo camphor
added to the paste while it is hot gives its
peculiar odor to the best kind of India ink