chrmical halance as a measuring roul of precision. Wirh it thc chcmiit mn determine the optical constant5 of rhc marcrials with which he drals as well as the utlmr m o r ~commonly srudietl physical properties. The appearance of the second edition of Volume 1of the HANDBOOK 011 CHEMICAL.MICROSCOPY by Professors Chamat and Mason is, therefore, very timely. During the seven years that have elapsed since the first appearance of this work in the twovolume form, much progress has been made. Happily the second edition is not simply a reprinting. While i t has essentially the same organization as the first edition, i t differs in many details. New material, especially many new references appear on almost every page. New data have been added also to the tables. A few figures were added, a few were dropped. The section on particle size determination of the first edition has been expanded to a full chapter in the new edition. Important additions have also been made in the section dealing with the cryptocrystalline aggregates, oriented aggregates, and so forth (such as textile fibers, nitrocellulose, starch). Minor changes appear in the sections on illumination, photomicrographs, preparation technic and crystals. Condensation or omission of less essential materials has made the new volume more useful and yet no larger than the old. The reviewer is doubtful whether the section on crystal morphology is yet adequate t o provide the background needed for the understanding of the optical and crystallographic data found in the literature, and in the newer handbooks and tables. The section on crystal optics is still rather brief, though perhaps the careful execution of all experiments described and supplementary lectures will make this part satisfactory. The authors and publishers are to be thanked for providing us with a new edition of this most useful work. F.J. PETIIJOKN
tions, and some glaring errors of fundamental viewpoint (such as the statement that oxalic acid contains carbon in two different states of valence) have been corrected, hut thereremainsa certain tendency toward arbitrary rules which are not always fully explained. One finds an eight-step procedure for balancing oxidation-reduction equations, without any mention of the highly explanatory electron, and it seems that only an unusual student would remember such an involved procedure without some such simple key t o its meaning. The word "valence" is used without any attempt a t definition: thus bromine in the hromate ion is given a "valence" of +5, without any warning that a purely arbitrary convention is being employed. I n the chapter on potentiometric methods, the authors employ the European conventions regarding the signs of electrode potentials, without reference to the alternative system of Lewis and Randall. I n view of the widespread use of the latter conventions in more advanced instruction, it would have been valuable to describe both systems, and to show that the consistent use of either leads to correct results. On the whole, however, the third edition of this book represents a considerable improvement over the second, and it should be looked upon as a very useful aid t o teachers of quantitative analysis. ANTONB. BURG TYBUNrVaPSLTY OF C l r C & 0 0 C","rn". II.LIN"IS
THECHEMISTRY OF THE CARBON COMPOUNDS. Victor yon Rickter. Edited by the late Professor Richard Anschiite. Translated from Vol. 1111 of the XI1 German edition (compiled by Prof. A . Butenandt. Dr. M . Lipp, Dr. I
