Add Yahoo as a preferred source to see more of our stories on Google. William Abel, a mail censor at Iowa's State Prison, Fort Madison, using a hot iron to bring out a secret message written in lemon ...

A Hillhouse student’s eyes widened as he applied grape juice and heat to what appeared to be a blank piece of paper — but instead held a secret message in invisible ink, written as part of a course ...

My finger hovers over an iMessage obscured by a haze of dancing white dots. Before I tap to dissolve the sparkling pixels and reveal the contents of the message, I know it's going to be juicy, or at ...