It's the stuff of spy novels, except in this case it's the stuff of actual spycraft. A new exhibit opening in London features ...

Some have experimented throughout history with other acidic or alkaline substances, including urine, vinegar, onion juice, juice from other citrus fruits and semen. Lemon and grapefruit juice were ...

The intelligence agency’s exhibition at London’s National Archives delves into Britain’s history of spying and includes a 110 ...

The lemon, now black and shriveled, helped convict Karl Muller, a German spy in Britain during World War I. It was found by ...

In 1915, a German spy was executed after he was caught with a lemon in his pocket. A new exhibit in the U.K. shows how he used it for espionage.