Magnesium

The summer of 1618 saw England gripped by drought, but as Henry Wicker, a local cowherd, walked across Epsom Common he came across a pool of water from which his thirsty cattle refused to drink. The water tasted bitter and on evaporation yielded a salt which had a remarkable effect: it was a laxative. This became the famous Epsom's salts (magnesium sulfate, MgSO₄) and a treatment for constipation for the next 350 years. 

From it's humble beginning, John Emsley explores the journey of Magnesium.