VOJ. 5. No. 3
RECENTBOOKS
W s i o n pressure and osmotic pressure is quite common. The book mpplas a much-felt need and will prove excecdmgly useful to hrologiwl students. E m S. JOHNSTON The Electronic Theory of ~alehcy. N. V. SmGwrcK, M.A., Sc.D., D.Sc., P.R.S. Oxford University Press, Ameriean 310 Branch, New York, 1927. xii pages. 4 figs. 24 X 16 cm. $5.00.
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The book gives the fullest account yet available of the principles of valency and molecular constitution, based upon the Rutherford-Bohr atom. It attempts to interpret the fundamentals of valency in molecular structure in terms of the . physical concepts of electrons, nuclei, and orbits, without transmessing the physical laws which these physical entities possess. The book, therefore, outlines the theory of the nuclear atom, the Bohr wncept of the hydrogen atom, and the Bohr-Main, Smith-Stoner proposals for the position of orbital electrons in atoms. With this as a foundation it proceeds with the development af the electronic theory of valency, the familiar views of Kossel, Lewis and Langmuir constituting the fundaments1 basis of presentation. To the ideas of electrovalency and co-valency the wncept of co6rdinate valeucy is added. Having discussed the criteria of each, the applicability to Werner's theory of wardination is illustrated in detail. The idea of a coardinate link with one atom or group as donor of electrons and one as acceptor wnstitutes a necessary amplification and extension of Werner's ideas to double salts and to chelate or ring wmpounds in which latter one part of the molecule acts as donor to another part as acceptor. Molecular association in compounds is attributed to wardinate linkages, as also is solvent power, hydrate formation, and solvation. Atomic and molecular magnetism are then treated. followed bv a discussion of the stereochemistry of various elements
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in their compounds. A more detailed discussion of chelate rings is given and a final chapter is devoted to a skeleton outline of a future volume taking up the applicability of these ideas to the individual elements and their compounds. The author has undoubtedly given us a most lucid treatment of the subject and has succeeded in systematizing, with the aid of a few electronic postulates, a vast mass of iuorgsnic chemistry as well as organic. The book should be read by all teachers of chemistry. I t is already being used with success in at least one university (Princeton) as an advanced text for graduate students in inorganic chemistry. HUGHS. TAYLOR
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The Higher Coal-Tar Hydrocarbons. ARTHURERNEST EVEREST.Longmans, Green and Co., Ltd., New York, 1927. 334 pp. 22 X 14 cm. $7.00. xiii
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As pointed out by the author, the field of wal-tar hydrocarbons is far too extensive to be dealt with in such a volume as this and so 111 hydrocarbons up to and including napbth&ne and anthracene have been omitted. The author has collected and presented in a compact wellarranged form the known facts regarding the acenaphthene, fluorene, and phenanthrene groups of hydrocarbons, together with some miscellaneous groups not included under these headings. A great gain in clarity has been attained hy the care taken with the numbering of the various ring complexes. The number of suggestive things pointed out by the author are many and a few may he mentioned here. Speaking of pyrene, BsHlo, the author staks: "Despite the fact that this substance has been known for a considerable timeLaurent obtained it in an impure state in 1837-it has not yet attracted any great amount of attention, nor has it yet received any large technical application. Glaser has pointed out that this hydrocarbon contains a larger percentage
