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lation hut the protective colloid must Catalytic oxidations are discussed at some length hut the chief illustrations are not "poison" the catalyst. colloidal metal = The main part of the book is devoted methyl alcohol air HCHO; and 2CO 0 9 = 2'202. to a review of colloidal metal sols prepared A discus&m of the kinetics of colloidal by Paal's method (protalbinic or lysalbinic acids as protective colloids) or by Skita's catalysis is given but here the only remethod (gelatin or gum arabic as pro- action sufficiently well studied to be adetective colloids). Complete directions are quately discussed is 2H202--t 2H.O given for preparing P t sols containing 0,. The question of poisoning of the cat50Yo P t ; Pd sols containing 47% Pd; and I r sols containing 19% 11. These sols alystis discussedat some Length. Only tl-c Paal preparations have been sufficiently can be evaporated t o dryness, and heated a t 10&11O0C. and still be readily dis- well studied to generalize. Hg and HgO persed when water is again added. The are fatal t o hydrogenation reactions but properties of these sols are discussed in not t o the reaction 2H20z--t 2 H ~ 0 0 ~here, ; however, HgCh acts as a poison. considerable detail. Hydrogenation reactions are next taken As a rule oxides and hydroxides of other up and thc necessary apparatus is illus- metals are less effective poisons than is Hg. In the final section the author discusses trated. Directiansare given for the hydrogenation of acetylene to ethylene and eth- the theories of catalytic hydrogenation. ane; of phenyl propiolic acid to cinnamic There is a good discussion of the various acid; of nitrobmzene to aniline; and of ben- theories of hydrogen activation hut the author does not draw any definite conzaldehyde cyanhydrin to beneyl alcohol. Inorganic compounds can likewise be clusion as to the theory which should be hydrogenated by these preparations. In accepted. The book closes with a subject and the presence of protalbinic acid and a trace of colloidal palladium, Cu(0H). is author index. I n general, it may be reconverted by HS into a colloidal copper garded as treating a very limited portion sol. One milligram of colloidal Pd is of the general field of catalysis, wit\ essufficient to convert 0.2 gm. of CU(OH)~. pecial reference to the catalytic tehavicr Similarly sols of Ni and Co can be pre- of Pt, Ir, and Pd, and even here only those pared. Ammonium bichromate solutions preparations prepared bjr Paal's or Skita's methods. However, i t brings together a under similar treatment yield a sol of Cr(OH)$;ammonium molybdate solutions considerable amount of widely scattered yield a sol of MO(OH)~ and ammonium literature and as such serves a useful purmeta vanadate yields a sol of V(OHh. pose. It should he of interest t o those who are studying catalytic reactions and Paal's colloidal metals can be used as also to the organic chemist who may wish catalysts to hydrogenate double and trito selectively hydrogenate some organic ple bonds in aliphatic organic compounds but are without effect upon the carhonyl compound. Ross A I ~ GORTNER N group or upon the double bonds causing the aromatic character of benzene, naphthalene, pyridine, or quinoline. TheSkita Digest of Elementary Chemistry. MARTIN MENDEL,M.A. Globe Publishing preparation, on the other hand, will hyCompany, New York, 1927. v f 234 drogenate not only the aliphatic double pp. 22 figures. 12 X 18 cm. $0.67. and triple bonds but also the carbonyl The name indicates the purpose of the group and the aromatic carbocyclic and heterocyclic compounds, including even book, which is elaborated in the preface. "This book is designed t o present in canthe very resistant (to other methods of hydrogenation) isoquinoline. A number cise and logical form those essential facts of chemistry which are necessary not only of illustrations of methods are given.
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for the successfid completion of the coune as measured by examination results but t o supply that informational hackground which is conducive to good thinking." Each chapter dealing with descriptive chemistry begins with a summary of the reparation, properties, and uses of the substances treated, together with equations and diagrams of apparatus for the most important experiments. Following these are sets of questions or problems, about 9(X) in all. A chapter devoted t o I,aws, Theories, and Hypotheses includes a four-page treatment of the electron theory and an excellent periodic table giving electron diagrams of the first 25 elements. There is a chapter an Chemical Tests and one on Definitions. Tables of essential properties and Regents examination papers for the last five years conclude the book. The summaries of processes and properties are generally good, although the effort to condense, leads to statements in the theoretical portion that are not always clear. The questions are much broader than the summary text. The figures are clear and notably well labeled. All problems are grouped in one chapter with a very large proportion of them involving volume relations. This digest is better done than most such books. I t should be used for review purposes only. Most modem texts have summaries, and the use of a new set for review dws little to form habits of independent study. Questions differently worded from those the pupil is accustomed to hear are valuable, and the scope and wording of those in this book arc excellent. The implication in the preface that a digest might be substituted for a well organized textbook is unfortunate, as it involves the doubtful ethics of cramming a pupil to pass an examination in a subject that he has not mastered. R. B. BROWNLEE
try Department, Boys High School, Brooklyn, N. Y. The Globe Book Company. New York City, 1827. 182 pp. 7 figFirst edition. vi ures. 12.5 X 19 cm. 51.20.
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As the title indicates, this is a hook written to strengthen the student in the calculations encountered in first-year chemistry. The author bclicves that while the lamentable weakness of the average "beginning" student is due in part t o failure to grasp the reasoning process involved, a larger factor is the lack of properly graded problems in the average textbook. "The aim of the hook is t o provide a wealth of material in chemical calculations by means of which the course may be vitalized and strengthened in those parts which are so often considered difficult and uninteresting." The book includes 14 chapters and an appendix consisting of 8 tables of data needed for solution of the problems. The title does not fully cover the scope of the book. Chapters I , "Matter, Changes, and Atomic Structure;" 11, "Symbols, Formulas, and Molecular Weights." and V1,"Chemical Equations," are purely theoretical and duplicate material t o be found in any good textbook. They are simply and clearly written, however, and the duplication is no doubt justified in view of the importance of the material treated. Most of the chapters present briefly and elearly the theory underlying the type of calculation considered, then solutions of several typical problems, then a wellchosen group of problems for the student t o solve. Chapter XI1 includes272 problems, grouped under the chapter headings of the average textbook, which makes them admirahly adapted for outside assignment as the coune progresses. Chapters XI11 and XIV consist of 54 selected problems from those set by the State of New York and by the College Entrance Examination Board. A total of 148 study questions and 625 problems are included in the book. No answers are given. Teachers of college courses will he quick L.DINSChemical Calculations. ERNEST MORE, A.B. Chairman of the Chemis- t o note several serious omissions, among
