After
World War II, Josten returned to England, and in 1954 he became a naturalized
United Kingdom citizen. Josten became Curator of the Museum of the History of Science at Oxford in 1950. He was an expert on the early
history of chemistry (
alchemy),
astronomy, and early astronomical instruments. On his early retirement in 1964 aged 52, Josten took an
emeritus curatorial position at the museum. He encouraged his successor,
Francis Maddison, who was previously an assistant curator at the museum. Josten was a member of
Brasenose College, Oxford, which was also the college of Elias Ashmole. He was also a Fellow of the
Society of Antiquaries of London. He lived in rooms in
St John Street, Oxford. He married Constanze Josten in 1962. She died in 1968. ==Works==