Secret letters written in semen Secrets revealed ... the book BRITISH spies experimented with using SEMEN to write top-secret letters. Spooks at MI6 discovered the bodily fluid could be used as an invisible ink, as it glows brightly under UV light but does not react to detection chemicals. The tests are detailed in a diary entry written during the First World War by a senior member of the Secret Intelligence Service. Walter Kirke wrote in June 1915 that Mansfield Cumming, the first chief of the SIS, was "making enquiries for invisible inks at the London University". In October he noted that he "heard from C that the best invisible ink is semen", which did not react to usual methods of detection. It also had the advantage of being easily available. One member of staff close to Cumming, Frank Stagg, said he would never forget his bosses' delight when the Deputy Chief Censor said one of his staff had discovered that "semen would not react to iodine vapour". Stagg noted: "We thought we had solved a great problem". However, the discovery also led to some further problems — the agent who made the discovery had to be moved from his department after becoming the butt of jokes. At least one agent also had to be reminded to use only fresh supplies of semen when correspondents began noticing an unusual smell. The revelations are included in new book MI6: The History of the Secret Intelligence Service 1909-1949 by Professor Keith Jeffery. Prof Jeffery, of Queen's University, Belfast, was given access to all of MI6's files between those years.
Walter Kirke wrote in June 1915 that Mansfield CUMMING, the first chief of the SIS, was "making enquiries for invisible inks at the London University".-rotfl
you wouldn't want to write a long winded letter or have to draw a map for secret locations with this stuff. Not enough "ink"
