In spite of the difficulties which war-time placed in the way of publishers, the production of scientific books, both in England and Germany, has been astonishingly large during the past five years. The greater number of them have--naturally enough--been devoted either to technical subjects or to branches of science having an immediate technical application. The field of industrial chemistry, especially, has been well tended by the writers, and not only new books, but new series of books--such as Messrs. Longmans' _Monographs on Industrial Chemistry_, Messrs. Churchill's _Textbooks of Chemical Research_, and Messrs. Baillière, Tindall, and Cox's _Industrial Chemistry_ series--have appeared to bear witness to the activity of the English chemists. Certain subjects in particular have been extensively treated; we may instance synthetic colouring matters, colloid chemistry, and catalysis, the last-named subject having books devoted to it in all the series just specified. In these the subject is handled from the industrial point of view, but it is frequently seen that the commercial and the theoretical developments of a science are mutually stimulating, discoveries made in the laboratory without any object but the wresting of knowledge from nature finding commercial application, and the commercial processes suggesting fresh theoretical problems. The great industrial importance of catalysis has led to a revived interest in the scientific theories of the process, and the latest book on the subject, by Drs. Eric Rideal and Hugh Taylor, deserves praise for having devoted considerable attention to the historical and theoretical aspect of the subject, which has been rather neglected of late.