The Physical Properties of Gases. By Arthur L. Kimball. (Heinemann.)—The
author of this neat little treatise, who dates from the Johns Hopkins University, seeks, he says, to meet the wants of many who, lacking the time for a more thorough study of the subject ho treats of, wish to know something of modern views, and the basis on which they rest. But it will even appeal to and be appreciated by students in the ordinary sense. Mr. Kimball's method is good and—or because—it is simple. Ho treats first the properties which belong to gases considered as fluid masses, and then takes up those which depend on their molecular structure, reviewing finally the evidence for the Kinetic theory. All the chapters are distinguished for lucidity in exposition ; the eighth, on Avogadro's law, is exceptionally good. Mr. Kimball is the reverse of a wild theorist ; on the contrary, ho maintains that "beyond force and matter the physicist cannot go ; experiment can teach him nothing of this realm ; he can form no conceptions more fundamental than these; he has reached the Ultima Thule of physical research." The student, however, who desires, not brilliant hypotheses, but the actual results of research, will feel grateful to Mr. Kimball.