J. B. S. Haldane's new book of essays, previously published in England under the title of "Keeping Cool," takes up scientific and social problems from a point of view which cannot allow any segregation of the two. Professor Haldane's career as a scientist has been remarkable, both in its scientific and non-scientific aspects; he gave aid to the Spanish Loyalist Government as a consultant in the problem of gas attacks, and as a lecturer in Britain; he has been a consistent fighter against Fascism, at home and abroad; and he is the last man of research who has resisted evacuation from University College, London.

The adventures of which he writes so well have a greater right to be styled "adventures" than most of the thrillers chronicled by Lancelots of the microscope. Professor Haldane has an honorable history as a guinea-pig, both his father's and his own. He has had more experience of chlorine than it is to be hoped that the reader ever will; he writes: "I . . . drank large amounts of various chemicals in solution, some of which have since been used in medicine, though generally in smaller doses than I took. I think I hold the record for the amounts of ammonium, calcium, and strontium chlorides which I have taken." In one essay, "After-effects of Exposure of Men to Carbon Dioxide," he reprints his Lancet article on an experiment he made in connection with the Thetis disaster. This study, as its author points out, has both stylistic and factual interest for the average reader.

The account of science's various unsolved problems is skillfully and intelligently presented; but of even greater interest are Professor Haldane's brief studies in politics, religion, Marxism and a philosophy of life. These bespeak a wisdom, sanity and deep humanitarianism form which his progressivism logically proceeds. And the latter without the former is useless.