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W B find that ro = 4.425 cm. and, if the values of r, and rb given above are uszd, equation 17 is satisfied if a = 4.9. That is,
6r:/2 = 4.9 or 6 = 0.57
This cannot be used as a precision method but should be useful for indicating the order of magnitude of df. REFERESCES (1) AHCHIBALD: l'hys. Rev. 6.9, 746 (1938). (2) .4ncmsALD: Ann. K . E'. Acad. Sci. 43,211 (1942). (3) SVEDBERG ANI) I'EDBRSEN: '/'he I'llracenlrijuye. Oxford University Press, London (1940).
KEW ROOKS Practical Physioluqiral Chernislty 12th edition. BY P H i L r r n. H A W KB, E R N A RXi. D OSER, ANI) WILIJANH . SI-KW:RSOS. s i v 1323 pp. Philadelphia: The Rlakiston Company, 1947. Price: $10.00. The twelfth edition of this well-known book will be welcomed by everyone who is interested in this particular field All the subjects pteviously covered have been revised and several new sections have IJeen added. This results in a very complete coverage of the topics which fall within the srope of the title. The subjects covered, which are presented in the more or less conventional order, are a s fLJll0WS' wine physir,ochcrnical properties of solutions; the chemistry of carbohydrates, fats, proteins, and nucleic acids; the chemistry of milk; the chemistry of epitholial and connective tissue, teeth, muscular tissue, and nervous tissue; enzymes; the chemistry of digestion; intestinal absorption; putrefaction and detnsication; feces; the chemistry of blood and blood analysis; the chemistry of respiration; energy metabolism; hormones; the constituents of urine and their determination in urine; carbohydrate, fat, protein, and inorganic metabolism; vitamins and deficiency diseases; and antibiotics. I n addition there are nine appendices covering such topics a s : reagents and solutions; composition of foods; tahles of logarithms and atomic weights; analysis of variance; and maintenance of aninials for nutrition esperimcnts. .new sections Coricwning the new material, the senior author states in the preface, '' have been introduced o n the polarograph; on isotopes; on the sulfa drugs; on metabolic ant,agonists and antibiotics; on the Warhurg tissue-slice procedure; on the theory and pract.ice of photometric analysis; on the electrophoretic fractionation of the plasma proteins; on the composition of foods; and on the various vitamins whose importance has become recognized since the last edition together wit,h a fuller discussion of the clinical relationships of certain vitamins. Also many new quantitative procedures for blriod and urine have been added." All tlie material is presented in a clear manner; the experimental procedures are very d e t d c d and casy t o follow.. T h e large number of illustrations (329 text illustrations and 5 color plates) add much t o the quality of the hook. With regard t o nomenclature and symbols, some changes have t e e n made from previous editions. As an example, the term milliliier has been used in place of cubic centiirieler as a unit of volume. The presentation of numerous chemical formulas is quite useful and mhances the value of the book a s a reference.
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I n format the book is first class, the binding and paper being of high quality. This book can be easily recommended t o anyone in the field of physiological chemistry. As a laboratory text and reference book i t is excellent. I t should be especially useful to anyone who is teaching laboratory work and t o all students doing graduate work in t h e field.
CHARLESCARR. Mesot&Theory of Nuclear Forces. HY WOLFGANG PAULI.69 pp. S e w York C i t y : Interscience Publishers, Inc., 1946. Price: $2.00. This small volume b y one of the most distinguished and active workers in the field of meson physics is based on lectures given a t the Massachusetts Institute of Technology in 1044, the notes of which are here published in but slightly amended form. Within the compass of sixty-nine pages Professor Pauli has given the meat of all aspects of the current theory, for both charged and uncharged mesons, and for the so-called weak and strong coupling forms of the theory. The treatment is really only a summary, rather than a n ekposition. of the theory and is scarcely adapted for a first introduction; for the more sophisticated reader in quantum-methanical literature i t will give an illuminating account of the present state of affairs in the theory of mesons. While the theory is unquestioiiably a brilliant attempt t o extend the electromagnetic theory of photons, and in a certain sense has been vindicated by the discovery of mesons in cosmic rays, the present ambiguous state with respect t o nuclear forces and the inherent mathematical difficulties make i t difficult t o guess in what sense it will remain a8 a permanent part of our conception of nature. Professor Pauli's discussion gives a balanced account of both the successes and the failures of the theory t o date. EDWARDI,. HILL.
FouTier Y'ramj(ir~iisand Slruclirre lg'actors. By DOROTHY WRINCH. 96 pp. Monograph S o . 2 of t.he American Society for X-Ray and Elect,ron Diffraction. February, 1946. Copips of the monograph can be obtained from the Treasurer of the Society, Dr. C . C . Murdoclc, Department of Physics, Cornel1 University, Ithaca, New York. Price: 54.00.
In just t,he same way t h a t a crystal structure can be represented in terms of a reciprocal latt,ice every point of which is weighted with its corresponding structure factor, a molecule can be represented in terms of weighted reciprocal space (.4. Hettich: %. Icrist. 90, 483 (1935). 1'. P. Ewald: %. Krist. 90, 493 (1935). G. K n o t t : Proc. Phys. Soc. (London) 62, 229 (1940)). Such a representation is called the molecular structure factor, which is very closely related t o the Fourier transform of the molecule. This representation has proved particularly useful when the geometry of the molecules or groups comprising a crystal is known and the problem is to determine their relative orientation (A. Charlesby, G. Finch, and H. Wilman: Proc. Phys. 8oc. (London) 61, 4 i 9 (1939). J. Waser and C . S. Lu: J . Am. Chem. SOC.68,2035 (1944); the power of the Fourier transform is illustrated by its use here in reducing the original fifty-four unknown parameters in the biphenylene crystal t o four). I n this short and excellent monograph, Dr. Wrinch has recorded the Fourier transforms of a large number of structural types, many of which occur frequently in a wide variety of crystals. These types include points of a lattice (Chapter 3) and, among others, tetrahedral, octahedral, and hesagonal sets of points (Chapter 4 ) . The discussion is extended (Chapter 5 ) t o set.8 of many points on surfaces and within volumes based on a cubic lattice. The transforms of continuous distributions (Chapter 6) permit a discussion of composite distributions 6 ( D ) ,in which continuous distributions D are repeated by parallel displacement a t any of the sets of points 6 . Three classes of applications are mentioned: ( I ) When D represents a n atom, the composite distribution yields the transform of like or closely similar atoms a t the points of one of the sets 6. ( 8 ) When D represents the unit of pattern of a crystal and 6 the set of points of the lattice, the composite distribution is the crystal, and its transform is defined only a t reciprocal lattice points. (3) When 6 is a
