CIA reveals World War I recipe for `invisible ink`

CIA claims to have lifted the lid on the "secret writing" in World War I.

Last Updated: Apr 20, 2011, 20:17 PM IST

Washington: The CIA claims to have lifted
the lid on the "secret writing" practices during World War I,
revealing how "invisible ink" was used by spies, generals and
diplomats to send secret correspondence between allies.

The six de-classified CIA documents, dating back to
WWI, painstakingly detail the recipes of the "invisible ink".

"Mix 5 drams copper acetol arsenate. 3 ounces
acetone and add 1 pint amyl alcohol (fusil-oil). Heat in water
bath -- steam rising will dissolve the sealing material of its
mucilage, wax or oil," `The Washington Post` quoted one of the
documents as saying.

But there`s a warning for the intrepid spy: "Do not
inhale fumes."

One document lists chemicals and techniques to create
invisible ink for what is charmingly called "secret writing".

Another document from June 1918 and written in French provides
the formula the Germans used for invisible writing during WWI.

Another describes how to carry invisible ink in one`s
clothes. Spies were instructed to soak their handkerchief or
starched collar in a mixture of nitrate, soda and starch
before drying the fabric.

The instructions continue: "The article thus treated
is later on again put in water and a solution obtained, which
can be used for invisible ink. The best means for developing
are iodite of potassium."

And spies weren`t just taught to make invisible ink --
they were told how to interpret it, too. Instructions include
"examine through powerful beams of light directed on surface
at different angles` and `run a warm iron over the surface".

They documents were originally kept by the Office of
Naval Intelligence, decades before the CIA itself was founded.

In a statement, CIA Director Leon Panetta said:
"These documents remained classified for nearly a century
until recent advancements in technology made it possible to
release them. When historical information is no longer
sensitive, we take seriously our responsibility to share it
with the American people."

PTI