TheCodeBreakers
for the secret writing on the handkerchief of George Dasch, leader of the
eight Nazi spies who landed by submarine on Long Island in 1942 to
blow up American defense plants, railroad bridges, and canal locks. The
red letters that appeared as if by magic when the pungent ammonia
reached it spelled out the names and addresses of a mail drop in Lisbon
and of two reliable sources for help in the United States. Each of the
eight saboteurs had also been given a watertight tube containing four or
five matchsticks tipped with a grayish substance that served as a ready-
made pen-and-secret-ink. The trick in concocting a good secret ink is to
find a substance that will react with the fewest possible chemicals— only
one, if possible, thus resulting in what is called a highly "specific" ink.
To test for secret inks, censorship stations "striped" letters. The
laboratory assistant drew several brushes, all wired together in a holder
annaabi.ee 
