Who,what,where

In 1618 a farmer at Epsom in England attempted to give his cows water from a well. This they refused to drink because of the water's bitter taste. However the farmer noticed that the water seemed to heal scratches and rashes. The fame of Epsom salts spread. Eventually they were recognised to be magnesium sulphate, MgSO4. Black recognized magnesium as an element in 1755. It was isolated by Davy in 1808