Williams then spent another period back at Merton, having won a junior
research fellowship, Then, “out of the blue, in 1954,
Cyril Hinshelwood, then Oxford Professor of Chemistry, asked to see Bob.” He was told that three colleges—Christ Church, Pembroke and Wadham—needed a tutor in chemistry. “Each one will invite you to dine. Come back again in two weeks to give me your decision.” William's work in pure inorganic chemistry led to a two-volume textbook of inorganic chemistry, written with Courtenay Phillips, He became increasingly interested in enzyme catalysis, and in particular the role of metal ions, as for example the role of copper in proteins. He and
Bert Vallee proposed of the concept of the
entatic state whereby atoms and groups in enzyme active sites are maintained by binding to the apoenzyme in positions and states appropriate to catalyse reactions. In the same year
Peter Mitchell proposed a similar idea in the form of the chemiosmotic hypothesis. In a special issue of the
Journal of Theoretical Biology in celebration of 50 years of its existence Williams described the correspondence between Mitchell and himself. Williams contributed to understanding of the distribution of the chemical elements in living organisms and in collaborationwith
João J. R. Fraústo da Silva he wrote three books in this area, as well as a book with
Rosalind Rickaby on geological aspects of life. Williams retired in 1991 and devoted much of his retirement to the writing of the books mentioned.
Awards and honours Williams was appointed
Member of the Order of the British Empire (MBE) in the
2010 New Year Honours for services to the community in North Oxford. He was elected a
Fellow of the Royal Society (FRS) in 1972 ==Personal life==