Thorium nitrate from Soddy's laboratory, 1900.
© Science Museum / Science & Society Picture Library
This glas jar of Thorium Nitrate (Th(NO3)4) is labelled 'Thorium Nitrate Dr O Knofler and Co, made 25/II/1900'. Frederick Soddy (1877-1956) was an English chemist who conducted research on the transmutation of elements. Atomic transmutation is the changing of one type of atom into another as a result of a nuclear reaction. Thorium is a radioactive element.