Referee's report by Charles Herbert Lees, on a paper 'Critical and co-operative phenomena. IV. A theory of disorder in solids and liquids and the process of melting' by John Edward Lennard-Jones and A F Devonshire Sectional committee: Physics Recommended for publication in Proceedings. The recap of previous work could be reduced. Some of the description should be amplified. [Published in Proceedings of the Royal Society A, 1939]. Endorsed on verso as received 18 January 1939. January 1939