THE popularity of Prof. Stewart's book shows that it meets the requirements of certain kinds of readers. It can scarcely appeal to the serious student of physical and inorganic chemistry. A good deal of the material dealt with would not commonly be said to belong to either of the branches of chemistry indicated in the title. Much of it is pure physics, such as the long descriptions of X-rays and positive rays, and it is noteworthy that in just these cases good recent monographs by experts, not too large or beyond the capacity of students, are available. Would it not have been wiser to utilise this space for the description of some less accessible recent advances in inorganic or physical chemistry? Recent Advances in Physical and Inorganic Chemistry. By Prof. A. W. Stewart. With an Introduction by Sir William Ramsay. Fourth edition. Pp. xvi + 286 + v plates. (London: Longmans, Green, and Co., 1920) 18s. net.