326
JOURNAL O F CHEMICAL EDUCATION
The author has achieved a remarkably thorough and in many ways novel presentation of his subject. In great detail and with many drawings, he has discussed the determination of ionization constants, t h e ealculatian of pH, buffers, "ioniaation fractions," various kinds of titration curves, feasibility of titmtion, and titration errors. He has outlined the material systematically in the table of contents, which covers 13 pages. His list of symbols and abreviations runs to seven pages. Leafing through the book upon first examination of it, one receives the impression that it must average a dozen mathematical equations per page. Awed by the author's ;accomplishment, the reader will agree that the latter part of the purpose expressed in the prefaco has been realized. Yet, although it ia probably not important, one may doubt, that it has been done without depending upon theories of the mechanism of ionization. Moreover, the book might have been more readable if the author had been satisfied to use the generally accepted symbols rather than inventing so many of his own. For example, to designate the concentration of hydrogen ions, he uses a oapital H in italic; to designate the aativity of hydrogen ions, he uses a oapital H in boldface. Such deviations from standard pracbice make the book more difficultto read than i t ehould be. Sometimes the book is verbose; occasionally it is obscure. The second sentence of the first paragraph is a typical example; it reads as follows: "The 'reaction' or condition of the pure rolvent will be taken as the meaning of neutmlilg." One may also regard the author's distinction between salts on the one hand and acids, bases, and ampolytes on the other hand as unjustified, artificial, and oontrary to his statement of purpose in the preface. Experimentally, it is generally agreed that m m y salts are acidic in water and that many others are basic. However, despite these minor points, tho hook is a remarkable contribution to the field. Pvobably it will remain the last word for many years to come.
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INITIATION AND GROWTH OF EXPLOSION IN LIQUIDS AND SOLIDS
(Cambridge Monographs on Physics) F. P. Bowden and A. D. Yoffe. Cambridge University Press, New York. 1952. xii 104 pp. 68 figs. 20 tables. 5 plates. 14.5 X 22.5 cm. $4.50
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THEinitiation of an explosion is a complex and sometimes seemingly mysterious ~eriesof phenomena. The reason for the occurrence of an explosion is a t times obscure and the resulting destruction may prevent retracing to the heginning of the process. The apparent lack of reproducibility and difficult techniques neoessarily involved have not made this an inviting field of research for many scientists. Professor Bowden and his students have constituted one of the few groups who have worked in this field and they have done much to clarify the thinking about the explosion processes. "Initiation and Growth of Explosions in Liquids and Solids," one of the series of Cambridee M o n o m a ~ h son Phvsies. is an exoosition of a relativelv simile idea &n>ernine the beiinnine
surfaces, perhaps enhanced by a particle of grit, or by impact which may result in the adiabatic compression of an air bubble. Whatever the source of the hot-spat, if sufficient energy is cancentrated s t a point it will start an explosion. These hotapots, which mtLy be to 10-8 cm. in diameter, provide a sufficient concentration of heat to ignite the explosive. The process pictured as following the ignition is essentially that of a van't Hoff thermal explosion. A considerable amount of relatively simple but elegant experimentation is desorihed which has been developed bo test this basic idea. The techniques described include high-
speed photography as well a s a veryelementarydesrriptio~rof the use of the image converter tube for photography. Throuehout all this work Bowden and his eo-workers have used only minute quantities of explosives. Hence they have not studiedthesteady-statedetonationwhichoccurs in bulkexplosives. They assume, probably correctly, that the mechanisms which they have studied are the initial steps in a lsrge-soale explosion. The principal chapters of this short book me concerned with friction initiation, impact initiation in both liquids and solids, and the growth of the explosion to full-scale detonation. I t is filled with pictures and diagrams and its style is particularly readable. Since, as is painted out, the incidence of explosion i~ to some degree erratic, i t is to be regretted that the authors have not always used as sound a st,atinticnl approach to this work as might be desired. The sample is often toosmall to he conclusive. On the whole this is an excellent hook which adds much to a field in which the m i l a b l e literature is entirely too limited. I n fact the bibliogrilphy a t the end, which contains less than 100 references, constitutes a goo3 list (psrticulsrly of British work) of the unclessified puhlioationfi in thia field. ~~~~~
PAUL M. IiYE U. S. NAVAL ORDNANCILABORATORY S l ~ v e nSpnmo. M ~ n r b ~ a n
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ELEMENTS OF FOOD ENGINEERING. VOLUME I
Milton E. Parker, Consulting Food Engineer, Director and Professor, Food Engineering, Illinois Institute of Technology, Chicago, with the collaboration of Ellery H. Harvey, Professor of Food Engineering, nlinois Institute of Technology, and E. S. Stateler, Consultant on Fwds, Wahl-Henius Institute and Professorial Lecturer in Food Engineering, Illinois Institute of Tech386 nology. Reinhold Publishing Corp., New York, 1952. ix pp. Illustrated. 16 X 23.5 cm. $8.75.
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THIS first of three projected volumes proposes a. definition of food engineering and presents classes of unit operations and unit processes as they apply specifically to food processing. Most chemical engineers and mechanical engineers in the food industry may find that this new professionsl desoription of food engineer fits them more aptly. However, beyond the first chapter entitled Engineering Factors in Food Prooessing, the authors become almost completely concerned with qualitative descriptions of food proeessing and exclude almost entirely any engineering aspects. Perhaps such treatment is attributable to the infancy of food engineering. Or the authors may be reserving far the Inter volumes the principles of process design and equipment. As general technology preliminary to'food engineering, this volume is refreshing, interesting, and pictorial; it is alive with names of processing people, novel classifications, definitions, tables of standards, and statistics. The beginner student should find this hook engrossing and stimulating. The seasoned food technologist will reeognise numemus advances in processing technology although he is likely to find the treatment of his own specialty less than authoritative and nometimes vague. I t is not atypical of the industrv that when direct knowledee and familiarita are Inking, orrs nlubr oitvr. clrpvml nupm ~ourwtithat are itrr~nlplvte ctr w h d ~ m l p h n w r u~rclulvrertnir, points of vicw, leucling to :xn imbalance in presentation. The early chapters are fascinating treatises dealing with nutritional aspects, and economic and processing factors of food production. Thereafter the function of this volume beeomea that of describing the processing of "refined foods." These include the headings: wheat and corn flours: rice and oats millinn: minor cereal flours: fats and oils: suears. siruos. starches. ucts; and nuts. JOHN H. N A I R AND EDWARD SELTZER
