Acid tabs. These pieces of paper are impregnated with acid", or lysergic acid diethylamide (LSD). LSD is a psychedelic drug (it changes the level of consciousness) and a hallucinogen. It is commonly used for recreational purposes, despite being illegal in most countries. Colourless, odourless and easily synthesized it is non-addictive and non-toxic, but its effects are unpredictable. The drug was first synthesized by a German chemist, Albert Hofmann, in 1943. In 1947 the US Central Intelligence Agency began experiments with LSD, often on unsuspecting victims. It was also used by psychiatrists in the US. It was banned in the US in 1965, and in the UK in 1966."