such omissions have been the chief reason for which the sterner chemists have damned previous attempts t o humanize the science. I n the interest of culture and because of recent advances, chapters and sections have been added which, of course, were not present in the original Smith texts, and here the author has emerged from the shadow of his master. The chapter on atomic structure is unusually complete as well as clear and interesting. The chapters on plant and animal life and the chapter on synthetic products are perhaps the most valuable from the cultural viewpoint. A few pictures of noted scientists, a valedictory including a list of the winners of the Nobel Prize in chemistry, lists of medallists, the presidents of the American Chemical Society, and the inspiring accomplishments of all t h e s e s u c h inclusions seem quite apropos since culture must presume a recognition of persons as well as a knowledge of their works. At the end of certain chapters there are numerous references t o recent hooks and journal articles. These are largely popular in nature and, if the student could be persuaded t o read a few of them, they would certainly stimulate his interest in chemistry. It is a t least to he hoped that they may be read by his instructor! I n general, this textbook is one which a chemist must feel that he would have liked as a student. It is particularly t o he recommended as a reference hook t o those instructors who wish t o impress their students with a m m liberal view of chemistry.
HARVEY A. NEVILLE Colloids. H. R. KRUYT, Professor of Physical Chemistry, University of Utrecht, Holland. John Wiley and Sons, New York, 1927. xi 262 pp. 116 figures. 15 X 23 cm. $3.50.
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This is an excellent text, well balanced, and the most modern of its size and type. Adsorption is clearly presented with quite a leaning toward the orientation theories of Langmnir and of Harkins. Capillary electrical phenomena receive rather exten-
sive treatment and, of course, Kruyt's own excellent work on flow potentials is well even. The author has done notable work on the stability of colloids and it is an advantage to the reader to have this research summarized by Kruyt himself. Kruyt shows, for instance, how an emulsoid may he dehydrated by alcohol or acetone t o the suspensoid state, sensitive to low ionic concentrations. Perhaps we might quibble OW the reference t o hvdroxide sols as lyophohe colloids. The oxides of some of the metals such as fenic oxide are really noticeably hydrated although not comparable to agar or albumin. The author is more careful than most of us in using the symbols "m r" where we incorrectly write "lrp" for "millimicron." Kruyt's comments on Perrin's colloidal atmosphere are sane and in general we are impressed by the soundness of his views. He takes sharp issue with Loeb on the overwhelming importance of $H values in a gelatin sol. By the use of certain other ions than hydrogen or hydroxyl he brings gelatin to an isoelectric point a t varying Pa values. Biologist followers of Loch will do well to study carefully the convincing evidence presented by Kruyt. Yet Kruyt insists that Loeb's own views suffered a radical change from 1918 t o 1923 and would have been modified much more hut for his untimely death. Illuminating views are also expressed in this book on the Donnan equilibrium and membrane notentials. Phyzicicts and bi~logirtrwill join colloid rhaniits in apprecinrm~ of this valu.dde - hook. H A RN. ~ HOLWS ~ Principles of Organic Chemistry. DAVID E. WORRALL,Ph.D., Professor of Organic Chemistry in Tufts College. Longmans, Green and Co., New York 312 pp. 14 X 20 City, 1927. xii cm. $2.50.
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Thewobject of the author, as set forth in'th
