West Virginia argus. [volume] (Kingwood, W. Va.) 1877-1946, 1879-07-05
sympathetic Inks.

A great number of sympathetic inks
may be obtained by means of reactions
known to Chemistry. For instance,
write on paper with n colorless solu-
tion of sugar of lead; II the water that
Is used for the solution be pure, no
trace of the writing will remain when
II becomes dry. Now hold the paper
over jet OF sulphurated hydrogen,
and the characters will Immediately
appear on the paper of an intense black
color. The following recipes for inks
OF this kind are more simple IL writing
be executed with dilute solution of
sulphate OF iron, the invisible charac-
ters will appear of n beautiful blue, II
the paper be brushed over with "A pen
Gil full of solution of yellow prussiate
of potash; or they will be black, IL "A
solution of tannin be substituted for
the prussiate. IL the characters be
written with solution of sulphate of
copper, they will at ouce turn blue on
exposing to the vapors of ammonia.
Another sympathetic ink is afforded by
chloride of gold, which becomes a rcd
dish purple, when acted upon by salt
of tin. a red sympathetic ink may be
made In the following manner: Write
with IA very dilute solution of pcrchlo-
ride of iron-so dilute, indeed, that the
writing will be invisible wher dry.
Bv holding the paper IN the vapor aris-
ing from long-necked glass flask con-
tanning sulphuric acid and few drops
of solution of sulpho-cyanide of pot
assium, the characters will appear of u
blood red color, which will again dis
appear on submitting them To the va
pors OF caustic ammonia. This cXpcr-
iment can be repeated ad intinitum.
During the war i'm India, some years
ago, important correspondence was
carried on by the English by means of
the use of rice water as writing fluid.
On the application of iodine, the des-
patches Immediately appeared I'm blue
characters. sympathetic inks which
are developed under the influence of
heat only, are much easier To use than
the foregoing. Almost every one, per-
haps, knows that IL writing be executed
on paper with clean quill dipped in
onion or turnip juice, 1t becomes abso-
lutely Invisible when dry; and that
when the paper Is heated the writing
at once makes Its appearance In char
acters of brown color. All albumi-
mold, mucilaginous and saccharine veg
etablc juices make excellent sympa-
thetic inks; we may cite, IA among the
best, the juices of lemon, orange, apple
and Dsar. dilute solution of chloride
of copper used for writing Is invisible
until the paper is heated, when the let
sers are seen of IA beautiful yellow, dis
appearing again when the heat that
developed them is removed. The salts
of cobalt, as the acetate, nitrate, sui
phate and chloride, possess like prop
erty. When dilute solution of these
salts Is used as an ink. the writing, al
though Invisible when dry, becomes
blue when exposed to heat. The adj
dition of chloride of iron, or of "A salt of
nicklc, renders them green, and this
opens the way for "a very pretty exper-
iment: II winter landscape be drawn
In India ink, and the sky be painted
with wash Of cobalt alone, and the
branches of the trees be clothed with
leaves executed with wash Of cobalt
and nickle, and the snow clad earth be
washed over with the same mixture, a
magic transformation at once takes
ON the application Of heat, the winter
landscape changing into summer
scene.