isotopes. Numerous examples are cited where the radio-elements are employed as indicators in analytical chemistry, in electrochemistry, in colloid chemistry, in the determination of powder surface, in inorganic preparations, in technology, physics, and physiology. The group of volatile hydrides (part 11) is treated under the following heads: Classification of the Hydrides; Preparation of Volatile Hvdrides of the H e a w Metals; Comparison of the Constants of the Volatile Hydrides: Comparison of the Volatile ~ y d i i d e s with other Volatile Compounds. The Natural System of the Chemical Elements (part 111) has the following three chapters: Periodic and Non-Periodic Properties of the Elements; Isotopes, Definition of the Concepts "Chemical Element," "Simple Element," "Complex Element;" The Number of Chemical Elements. This is a most interesting and suggestive book and is a notahle contribution to modern chemical theory. The translation has been excellently done. JAMES M. BBLL
since the book first appeared in its original form. The book is not recommended in general t o physicists but should find a place in an introductory and historic treatment of thermionics quite readable by high-school teachers of science and professional people who do not care t o go into the subject too deeply. There are a few mistakes and the careless use of mathematical equations may cause annoyance t o others than mathematicians or physicists, who are already accustomed t o these formulae. The book gives a very good picture of the development of thermionic phenomena. References are numerous and i t gives the impression of being written by one who is a scholar in the subject. The hook is not as rigorous, complete, or so mathematical as is Richardson's "Emission of Electricity from Hot Bodies," from which much of the material was taken. C. H. K U N ~ M A N
Pundamentals of Daiq Science. AssoCXATESoI. LOREA. RDGERS. American Chemical Society Monograph, No. 41. Chemical Catalog Company, N. Y., 1928. 543 pp. 31 figures. 15 X 22.5 Thermionic Phenomena. ?3ucam BLOCH. cm. $5.50. Mdtre de Conf6rences A la Facult6 der This comprehensive monograph repreSciences, Paris. Translated by J. R. sents the joint effort of no Less than twentyClark, MSc., F. Inst. P. E. P. Dutton & Co., New York City. x 145 pp. eight contributors. I t covers an extensive field in an orderly and systematic manner. 24 figures. 12 X 18.5 cm. $2.50. I n fact, its coherence and uniformity of Bloch's book on thermionic emission style as a manuscript is remarkable in view was probably of far more value as a "Conof the large number of individuals who ferences Rapports" a t the time it first contributed t o it. As a source of carefully appeared than it is today in the form of a selected facts gleaned from an extensive translation by Clark, as no reference is literature, it constitutes the most useful made in this book t o work done since 1920. and authentic document in its field of subThe last chapter of eighteen pages de- ject-matter. voted t o the application does not do iusThe monograph is divided into four tie to this field, as well as being difficult parts, each of which is further subdivided to follow. Probably no other single phe- into rhxptera. 1':rrL I , the conrtituents of nomenon has been more carefully studied milk, includei fire clnplers on the rornpuand generally applied in this decade than sition of milk and milk products, proteins thermionic emission. I t is a phase of one of milk, milk fat, pigments of milk, and of our largest industries-the radio indus- lactose. I n Part 11, the physical chemtry-which has grown up in this country istry of milk and milk products are in-
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C., 1928. 27 v pp. 14.5 X 23.0 cluded chapters an acid-base and onidaan. $0.10. tionweduction equilibria of milk, physical equilibria of milk, coagulation of milk, and The methods used by the United States freezing of milk and milk products. Part Geological Survey for analysis of the 111, the microbiology of milk and milk mineral content of waters are described products, covers sources and distribution in Water Supply Paper 596-H which of bacteria found in milk, metabolism and bas recently been issued under the above growth of bacteria in milk and milk prod- title as Pages 235-261 of "Contributions ucts, iduence of physical and chemical t o the Hydrolo= of the United States." factors on bacterial growth, and yeasts Copies may he obtained from the Superand molds of milk and milk products. intendent of Documents. Part IV, the nutritional value of milk and 0.REINMUTE milk products, and the physiology of milk Colloid Symposium Monograph. Val. V. secretion, indudes the two chapters bearEdited by HARRYB. WEISBR. The ing those titles, respectively. Chemical Catalog Co., New York If any general criticism of this hook is City, 1928. 394 pp. 15 X 22 cm. made, it will be that of too great brevity $6.50. in certain sections. This appears t o be particularly true of the first few chapters. This volume contains the twenty-four Thus the bases for certain conclusions are papers delivered a t the Fifth National rlot invnrinl,ly hid in an adequate manner, Symposium on Colloid Chemistry held a t which results i n 3 sornee,hat ilidxtic stylr. the University of Michigan, June 23 Certain inconsistenciesin the use of chemi- t o 25, 1927. Needless to say it is cal symbols likewise appear. A few addi- indispensable t o the library of every coltional words or phrases in the section deal- loid chemist, and i t would be a valuable ing with the methods of examination of addition to any chemical library. milk fats would aid materially in the interThe titles included are as follows: pretation of analytical data. 1. "Unity in the Theory of Colloids." chemistry of milk H. R. Kruyt. Part 11, the ~hysical . . and milk products, is particularly attrac2. "The Stability of Emulsions, Monotive to the reviewer. This difficult phase molecular and Polymolecular Films. of dairy science is treated in a manner that Thickness of the Water Film on Salt is both unique and unusually adequate. Solutions and the Spreading of Liquids," Each chapter is followed by a list of the Wm. D. Harkins. references which are cited in the tent. I n 3. "Adsorption and Crystal Form," this manner a bibliography, totaling more Chas. H. Saylor. than 1300 papers, is included in the mono4. "Adsorption from Solution by Ashgraph. Free Adsorbent Cbarcoals," E. J. Miller. In view of its completeness, this hook 5. "Some Unsolved Problems in the should prove useful to a wide range of in- Molecular-Kinetic Behaviour of Colloidal terests. Teachers of various branches of Suspensions," E. 0 . Kraemer. dairy science will undoubtedly use i t ea6. "The Measurement of Adhesion tensively as a convenient source of mateTension, Solid against Liquid," F. E. rial. I n addition, it should have a wide Bartell and H. J. Osterhof. sale among technologists, and manufac7. "Investigations on Molecular Sieve turers of dairy products. Membranes," Leonor Michaelis. C. H. BAILBY 8. "Synthetic Kidneys," Wilder D. Bancroft and R. L. Nugent. 9. "The Chemistry of Body Processes; Notes on Practical Water Analysis. W. D. COLLINS. United States Govern- The Nature of the Action between Gelatin ment Printing Office, Washington, D. and Electrolytes," A. L. Ferguson.
