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Hii1t.s” has undergone a few mitior revisions, including the addition of a very brief discussion of the Tesla discharge source. One of the most appealing features of the book-the plates covering portions of the spectra of numerous molecules-has been extended from 39 t o 65 reproductions of spectra in the new edition. Xew molecular spectrograms are given for NaH, MgH, ZnH, P H , MnH, NiH, N:, NS, PO, 1’2, O:, 0 4 , NO*, SiF, TiO, CO, and CHIO. h molecular level diagram for Na is a new feature of the present edition. I t should be pointed out that the conversion table for wave lengths in air t o wave lengths in unciio refers t o standard air only (i.e., air a t 15”C., 760 mm. pressure, and containing :L normal proportion of 0.03 per cent of carhon dioxide). The need of continuing revisions of this compendium of information on molecular speetr:i is emphasized by recent publication of data on HgIn (Phys. Rev. 1, 89 (1951)) for which no data are available in the new edition. The authors are t o be highly complimented in bringing it as up t o date as to November, 1049. J . R A N DRICSALLY,JR. Cheniicul Kiricticu. U y I h . r i i J . 1.arnLm. 408 pp. New York: McGraw-Hill Book Company, lnc., 1950. Price: $5.50. In the preface the author elates: “The object of this book is the presentation, within a re:ison:ibly small compass, of the more important facts and theories relating t o the rates with which chemical reactions occur.” Whether the author has achieved his goal or has merely presented :i limited portion of the subject of chemical kinetics is a matter of opinion :md depends to :i 1:irge rxtent on what the reader considers important. I n general, the cxperimcnt:il :iq)ects of tlic subject :ire treated as incidental to the theoretical. The theoretical trentniciit is essentially i i simplified version of what is contained in the more elabor:ite work, Theory of fialc I’roccssca, b y Glasstone, Laidler and Eyring. I n fact, the present t)ook on Chemical Kinctics might he used :IS an introduction to the study of this older hook. The subject matter in this book is divided roughly into two parts. Chapters 1 t o 6 and Cluipter 13 de:d primarily with elementnry reartiotis, i.e., reactions xhich can be thought of a s proceeding f r o m the initi:iI t o the tin:tl state in one step. Chapters 7 t o 12 discuss complex reactions which are thc result of various combinations of elementary reactions. The discussion of the experiinrnt:il tneasurement of rates is confined t o the first 55 pages vhich constitute C1i:ipters 1 : i r i d 2, entitled “SIeasurement of Reaction Rates” and “ E x perimental Methods.” Tlic student will find little here beyond what he has already read in i i n :iverage physical chemistry text. One is left with the impression that the only rate laws one needs to determine are the simple ones which consist of :L single term which pcrniits c:ixy integration of t h e differentin1 equation. There is no attempt t o show the student how to cariy out the study of a renction which follows R more complex rate law such :is w c find i n tlic iorni:ttion of hydrogen hromide, the reduction of hydrogen peroxide hy iodidr, o r :iny other law which must he expressed by two or more terms or by a complex fi.:irtioii. In the opinion of this reviewer this is a i l unfortunate omission, since only ii relalivrly sni:LIl iiumher of rc:ictioiis follow rate laws :is simple R S those discussed in these r1i:Lpters. Prrhnps the :iutlior did not consider such reactions iniportnnt, since most mntel i d of th:rt type is iiot included :i:iywhere in the book. There is no mention a t all of the rxtensive writings on kiiwtics 11y .-\bel or Bray and only the most meager reference t o the \ \ o i , k of such people as I A \Ier, .-\.It. Olson, Skrabal, atid others who have studied many systems of varying dcgrees of complexity in solution. I n fact, it niay bk said that the aut h o r hiis relied 1w:ivily o t i t h e h t : i for gnseous systems, thus severely limiting the SCCIJJC of the book. The theoi,etical treatment is based entirely on the “alJsolute reaction rate theory.” On pages 5 9 4 2 the author presents the “collision theory,” which he declares is unsatisf:ictory and pmceeds t o denounce frequently throughout the rest of the book. This strong preference for one point of view has led him to make some statements which do not stand up well under close srrutiiiy. Thus, on page 61 in discussing the “collision theory” he
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says: I ‘ . i t is hardly possible to interpret on this basis the abnormally high rates t h a t are sometimes observed.” The reviewer is not aware that anyone has ever advanced any theory which will have a reaction occur at a rate that is faster than the molecules can come together. In fact, on page 62 the author says: reactions will still be regarded as taking place on collision between reacting molecules, but the nature of a collision will be defined more precisely.” I n other words, his dispute is not with the gencral idea of a collision theory but with the method of calculating the number and evaluating the effectiveness of the collisions. Such being the case, the relative success of the two points of view depends on the relative cleverness of the advocates of each in selecting a set of assumptions which will lead to a suitable interpretation of the experimental data. Hence table 40 on page 229, instead of showing the superiority of the “activated complex” theory over the “collision” theory, shows that the author was better able to make assumptions for the former theory in three cases and for the latter theory in two cases. Again, on page 72 the author claims that the “collision theory” for bimolecular reactions of complex molecules predicts rates 105 to 10” times faster than does the “absolute reaction rate theory” and is in disagreement with experiment by such a factor. No data are given to support this statement and the reviewer knows of data which are directly contrsdictory to i t . Anothcr example is found on page 107, where he invokes the restriction on singlet-triplet trnnsitions to account for the slowness of some gaseous isomerizations, although on page 61 he has denounced the “collision theory” for failing to account for such slowness without the aid of such a crutch. In general, while the author is highly critical of what he calls “collision theory,” he is rather noncritical when applying his own point of view t o experimental data. For example, in table 30 on page 131 the data are supposed t o confirm a rough rule stated above the table, but the discrepancies between the experimental and theoretical columns run as high as a factor of 10’. The discrepancies between theory and experiment can also be brought out by comparing the ratio of the experimental factors with the ratio of the theoretical values for pairs of the reactions cited. Sometimes there is excellent agreement, but in others the ratios disagree by factors which range up to 10’. If one is t o be allowed that much leeway, i t should be possible to find plenty of theories to fit the data. Actually, the collision theory must give the same result as the absolute reaction rate theory if equivalent assumptions are allowed. It has already been mentioned that the examples of reactions discussed have been chosen largely from gaseous systems. Since the book does not claim t o cover everything in the field of kinetics, the author should be allowed such a choice. It is unfortunate that he has not always covered the literature on those reactions which he does discuss. As examples might be cited the decomposition of dimethyl ether, where he presents the work of Hinshelwood (1927) but fails to consider that of Leifer and Urey (1942), and the thirdorder reactions of nitric oxide with oxygen and the halogens, where he fails t o consider the work of 0. K. Rice, which showed that the dimer of nitric oxide exists in amounts sufficient t o make it an important intermediate in the reactions. I n spite of the faults which have been mentioned, the book has its good points. It is written in a style which should not be too difficult for the average student to understand. There are 44 figures and 51 tables to illustrate the discussion. The reactions which are discussed are grouped in a logical manner. The book is well printed on good paper and is bound in the excellent form characteristic of the series. Taking all things into consideration, it is probably as good a book as is available for use as a text on this subject. G . K. ROLLEFSON.
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Colloidal Dispersions. By EARLK. FISCHER. 387 pp. New Yolk: John Wiley and Sons, Inc., 1950. Price: $7.50. Colloidal dispersions constitute an ever-present factor in our everyday lives. The scope of this field is tremendous. The content of the present book is restricted t o “technical aspects of the subject” and is directed primarily to dispersions of finely divided solids in
