TheCodeBreakers
city for a week to see if anything suspicious turned up. During the
war, about 4,600 suspicious letters were passed along to the F.B.I, and
other investigative agencies; of these 400 proved to be of some
importance.
Problems that would not yield to the crude approach of the field
stations went back to the T.O.D. laboratory. Here, amid Bunsen burners
and retorts, Pierce and Breon, aided by an expert photographer and
laboratory technicians, cooked up reagents that would reincarnate the
phantom writing. Better equipped and more deeply versed in the nuances
of sympathetic inks than the mass-production workers of the field
stations, they had received a great stimulus from contact with one of the
great secret-ink experts of the world, England's Dr. Stanley W. Collins,
who had conducted this battle of the test tubes in two World Wars; he
spoke at the Miami Counter-Espionage Conference in August, 1943.
T.O.D. soon learned that Nazi spies were taking countermeasures to
annaabi.ee 
