You can use this method to protect you papers from whomever, just go down to a magic supply store and ask for flash paper or a commercially made liquid to make your own. Alternativly you can go to a chemical supply store house and obtain some Potassium Nitrate (also known as Saltpeter.) Mix this chemical in water, using as much of the chemical that will dissolve in water and then dip you paper in this solution and let dry.

Bookies today still may use this method, but another method they use is chalk and dry erasable marker boards. If a raid takes place they simply wipe their chalk or marker board down eraseing the information.

Methods like these are becomming less and less necessary since the advent of high powered computers and crypto software. Using a computer and crypto software like secure drive/device a bookie could keep the information on his computer on an encrypted drive and simply turn off his computer during a raid. If the bookie had selected his pass phrase correctly and took precautions about using swap files and other common security leaks the police, FBI, or other govenment agency would have little chance on opening up the encrypted drive.