The prominent characteristic of Professors _F.P. Venable_ and _J.L. Howe's_ text-book on _Inorganic Chemistry according to the Periodic Law_[47] is expressed in the title, and is the adoption of the periodic law as the guiding principle of the treatment, and the keeping of it in the foreground throughout. So far as the authors have noticed, the complete introduction of this system has not been attempted before in any text book. They have made the experiment of following it closely in their classes, and their success through several years has convinced them of its value. "In no other way have we been able to secure such thorough results, both as to thorough, systematic instruction and economy of time. The task is rendered easier for both student and teacher." After the setting forth of definitions and general principles in the introduction, the elements are taken up and described according to their places and relations in the periodic groups, and then their compounds are described successively, with hydrogen, the halogens, oxygen, sulphur, and the nitrides, phosphides, carbides, silicides, and the alloys. The treatment is systematic, condensed, and clear. The purpose of Mr. _John W. Troeger's_ series of Nature-Study Readers is declared by the editor to be to supply supplementary reading for pupils who have been two years or more at school. They are composed, moreover, with a view to facilitating the recognition in the printed form of words already familiar to the ear, and to making the child at home with them. In carrying out this purpose the author takes advantage of the child's fondness for making observations, especially when attended by his companions or elders. In doing this the aim has been kept in view not to weary the child with details, and yet to give sufficient information to lead to accurate and complete observations. Most of the chapters in the present volume, _Harold's Rambles_, the second of the series, contain the information gleaned during walks and short excursions. Among the subjects concerned are birds, mammals, insects, earthworms, snails, astronomy, minerals, plants, grasses, vegetables, physics, and features connected with the farm. These Nature-study readers are published as a branch of Appletons' Home-Reading series. (New York: D. Appleton and Company. Price, 40 cents.)