'Chasms of Delight' is rooted in chemist John Mann's fascination with psychedelic, narcotic and euphoriant drugs. He sets out a colourful history of their discovery and use, telling the story of mind-altering drugs, their contribution to the work of poets and artists, the iniquities of the drug trade and the popular use of drugs in the 60s and 70s. Timothy Leary's famous exhortation in 1968 to 'turn on, tune in, drop out' has been blamed for persuading the masses to play with drugs, but the truth is that by the time of the 'Summer of Love' we had already been experimenting with them for...