Wow, this is scarey, secret stuff! Shades of Wikileaks. I wonder how many lives were endangered by these revelations. Funny though - I seem to recall as a kid knowing that milk or lemon juice could be used for invisible writing, which was revealed when heated, and thus turning brown.http://www.bbc.co.uk/news/world-us-canada-13141473
CIA reveals invisible ink recipes used by WWI spies
Woman's feet - photo Science Photo Library Spies were told to watch out for secret messages written on body parts and engraved on toe-nails.
World War I spies engraved messages on toe-nails and used lemon juice to write invisible letters, classified documents released by the CIA reveal.
The six documents, amongst the oldest secret papers to be held by the agency, disclose a number of spying techniques.
The nearly century-old records include instructions "to suspect and examine every possible thing".
Is this an example of CIA genius? No wonder 9/11 happened under their noses. Dumbasses.
