FEBRUARY, 1953
107
In an appendix Dr. Baker gives a complete summary of the nomenclature rand symbols of the English school together with concise explmations of each such term and does it in only two and a quarter p a g e e a n ~ffectiverebuttal to that small group of American chemists whioh apparently feels that the English nomenclature is so ridiculously complex that it merits no serious consideration. It should be recalled that the thpoq- of hyperconjugation was a t one time known as the Bsker-Nathan effect. Although it is not true that Baker and Nathan were the first to suggest the possibility of "no-bond resonance'' (a term synonymous with hyperconjugation) it is true that the concept was almost never used in theoretical organic chemistry prior to their famous paper which appeared in the year 1935. Their success in using the concept wm linked to the important assumption that only G H linkages could become involved in hyperconjugative resonance. It is therefore pilrtieulsrly interesting to note that Dr. Baker now freely assumes the participation of carbonhdogen linkages in hyperconjugntive resonance in both excited and ground states. The presentation of the subject matter of the book is as rigidly limited to the theme of hyperconjugation as possible. However, in discussing the applications of the hyperconjugative concept to diverse organic reactions, Dr. Baker has found it expedient to introduce each new topic with at least one paragraph summarizing pertinent knowledge relating to the tapir. This practice adds immeasurably to the value of the book, especially since Dr. Baker possesses to a remarkable degree the ability to summarize clearly and in a few words the information which is essential for the understanding of a topic. A good example is the introductory paragraph to Chapter IV in which he summarizes the modern theory of tautomeric equilibria. His discussion of organic reactions also includes many references to recent theoretical developments which have not for the most part been included at all in other books on theoretical organic chemistry. ~ r all organic chemists I t is the opinion of the present u ~ i t that seriously interested in the elert,ronic theory of organic chemistry should read this monograph. A. EDWARD REMICK
0
of science to the problem. The student will find a discussion of such diverse subjects as the chemistrv of herbicides and their physiological effect, plant competition; and equipment for weed control in the book. Each crop presents it,s own individual weed problem necessitating variation in the method of the application or chemical or other means of weed control. The cereal crops and grasslands come as close as any crops in similar requirement in control pleasures. 2,4D has been espeoially outstanding for weed cantrol in these crops, but other chemicals and other. method8 me required for certain specialized problems. The increasing interest and importance of defoliation and preharvest maturation of certain crops to facilitate machine harvest provides another use for herbicides. The defoliation of cotton is extremely important to machine harvesting. For the f i s t time this problem has been recognized to be of sufficient importance to have a chapter in s. textbook devoted to it. "Principles of Weed Control" is an interestingly written hook. The student will also find the organization of material logical and easily understood. The organization of the book is a deperture from similar texts, in that portions of it are devoted to weed problems hy crops. On the ot,her hand, research workers map he someu-hat disappointed by thelack of depth of theinformation. Unfortunately, there is less emphasis devoted to the principle involved in the problem of controlling a. given weed than there is in s. description of currently employed practices. Moreover, the references cited a t the end of each chapter are not as up to date as one might expect in a book published in September of 1951, nor are they particularly exhaustive. Frequently references are brought up only to 1949 and in many of these cases there are later references. Illustrations in the book are generally good, but a few of the photographs show poor composition in that the presence of same individual or some item of equipment di~tractsfrom the point of the photograph. As is frequently the case with early books in a new field, a. few minor factual errors have creot in. This does not esaeeiallv detract from the value of a &I written book and can de overlooked in this case where the published information on points concerned is very very sketchy. On the whole, the student and interested layman in this field will find interesting and informative reading in the book. While a research worker will certainly want this book on his shelf, he will not find it a prtrtieularlr profound refrrence hook.
PRINCIF'LES OF WEED CONTROL
V. H. F R E E D
Gilbert H. Ahlgren, Professor of Farm Crops, Rutgers University and The State University of New Jersey; Glenn C. Klingman, Associate Professor of Agronomy, North Carolina State College; and Dale E. Wolf, Assistant Manager, Agricultural and Biological Section, Grasseli Chemicals Dept., E. I. du Pont de Nemovrs and 368 pp. Co. John Wiley & Sons, Inc., New York, 1951. vii 109 figs. 25 tables. 14.5 X 22 cm. $5.50.
+
WEEDShave been the bane of the farmer's existence since man first tilled the soil. I t has been only in the past two decades that the character of weeds, their identification, dissemination, habits of growth, and eradication have been intensively studied. As a result of these studies more and more effective means of weed control are being developed. The exact definition for a weed that would he universally applicable still defies the bed efforts of man. A plant in one situation may be a weed but in yet another it may have considerable economic vslue. Similarlv, since nature abhors a vacuum. many of these wild plants serve's useful purpose on waste lands by preventing soil errosion and a t the same time building up the soil. This diversity of eharact,eristics in plants when compounded with a wide variety of craps and situations under which the plant may occur gives a clue to the complexit,yof the problem of weed cont,rol. Weed control involves the application of knowledge from suoh diverse fields as botany, agronomy, horticulture, chemistry, plant physiology, and ecology. The aut,hars of this hook have a+ tempt,ed to show a direct application of these various branches
OBE(IONSTATECOLLEU~ C O R Y * LO~ R . E~ON
0
ELEMENTARY HEAT POWER
H.L. Solberg, 0. C. Cromer, and A. R. Spalding, respectively Professor and Associate Professors of Mechanical Engineering at Purdue University. Second edition. John Wiley & Sons, Inc., New York, 1952. xvi 624 pp. 308 figs. 13.5 X 22 cm.
56.50.
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THE second edition of this surcssful text in the heat power field has been expanded and kept up to date. It is essentially a text descriptive of equipment used in power generation. The first two chapters deal with fundamentals of thermodynamics and fuels and combustion. Thermodynamics can hardly be taueht in the 63 aeees devoted to it, oarticularlv when unite and dim&inns, the laws, properties,. the Row equation and the second law are all discussed. Nor can combustion cdoulations
which analytical values can be substituted. The last eleven chapters are the best. They are descriptive of heat power equipment: internal-combustion engines, fuelburning equipment, steam generation, steam power-plant. cycles, steam turbines, st,eam engines, pumps, drafts, fans, blowers and
