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attained approach molecular dimensions and little imagination is needed to visualize advances in microscopy that appear to be of the greatest importance to many fields of science. Besides the optical uee of electron beams, their importance aa image transformers in television and aa current multipliers is also discussed. The present tract affords a ready means of becoming acquainted with these modern developments. GEO. GLOCKLER.
A Course of Study in Chemical Principles. By ARTHURA. NOYESAND MILES S. SHERRILL.Second edition. 82 x 5f in.; 6 tables; xxv 554 pp. New York: The Macmillan Company, 1938. Price: $5.00. This famous text has been rewritten and rearranged,-a revision that had been contemplated before the death of the late Professor A. A. Noyes. The first five chapters were published in pamphlet form several years ago. The new arrangement is aa follows: Chapter I. Chemical substances in general; Chapter 11. The first and second law of thermodynamics; Chapter 111. Gases and kinetic theory; Chapter IV. Solutions and molecular theory; Chapter V. Solutions and ionic theory; Chapter VI. Reaction rates; Chapter VII. Chemical equilibrium; Chapter VIII. Phase rule; Chapter IX. Free energy values. The laat chapter includes a short discussion of the third law of thermodynamics and calculations of free energy values from spectrographic and heat data. These modern developments might have been rendered in a more extensive manner. The method used in the first edition, of teaching the fundamental laws and propositions of physical chemistry by means of problems is retained in the second edition. This procedure puts the burden of presentation upon the reader and student. Any individual who will work through the many excellent problems will be amply repaid for his efforts, for he will have covered the subject of physical chemistry in a thorough and complete manner. I t is evident that no person in any way even remotely interested in the subject of physical chemistry can afford to omit this volume from his “must purchase” list of books for his library. The notation used agrees in many respects with the one employed by Lewis and Randall. The book is an excellent text for students in physical chemistry and advanced courses and is to be highly recommended for the clear and precise presentation of an intricate subject. GEO. GLOCKLER.
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Proceedings of the Indian Academy of Science. Jubilee Volume of original papers prepnted in commemoration of the fiftieth birthday of Sir C. V. Raman. The volume contains thirty-eight papers by various authors and has been collected in commemoration of the fiftieth birthday of Sir C. V. Raman. Most of these papers pertain to the subject of the Raman effect, the theory of small vibrations, force constants, diffraction of light by supersonic waves, etc. Some are concerned with quite different topics having no connection with the general theme. The papers are written in English, French, German, and Italian. The volume should be of interest to research workers in the field of the Raman effect. GEO. GLOCKLER. Principles of Flotation. By IAN W. WARK. 101 figures; 39 tables; 346 pp. Melbourne: Australian Institute of Mining and Metallurgy, 1938. Price: 21s. From Australia, cradle of froth flotation, site of the first agglomerate tabling, and early user of skin flotation (DeBavey), comes now the best book yet written on froth flotation. The author WBS the first to publish anything on the modern cationic collectors which have made possible reliable flotation of silicate minerals. The
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emallest continent haa made some of the biggest contributions to the concentration of minerals by filming methods. Here is a truly critical and discerning book on the principles of flotation, s u m marizing not only the voluminous literature from the author’s own laboratory but thoroughly digesting other work,-American, British, German, and Russian,-as no one has ever done i t in English. The author hss been for some years in charge of the flotation research laboratory of the Department of Chemistry of the University of Melbourne. This is financed by a group of Australian metal producers, together with the Burma Corporation, Ltd. His papers in the technical press have always been valuable and independent. Physical chemistry aa a tool in research haa long shown its value, but too few of the previous experimenters have been properly equipped with this tool. Dr. Wark so saturates his argument with physicochemical concepts that he excels Gaudin, who has previously stood out in this respect, and he rivals Gaudin in clarity of exposition. The charts are numerous in which Wark uses various flotation results as functions of pH, thus expanding the work initiated by Gaudin. The chapter on depressanta is the best one in the book and is a fine critique from the physicochemical standpoint. Such an encomium does not mean that the writer has not erred nor that his standpoint is not debatable. The eras in growth of flotation theory are not shown, and the effort seems to have been to present a picture of the best present flotation theory, Historical sequence is usually lacking. The pioneers are forgotten or go uncredited. During the era of “oil” flotation, and especially between 1912 and 1917, the temperamental process of froth flotation was converted from one applied to only a few hundreds of thousands of tons of ore per annum to a reliable process working on over 50,000,000 tons per annum in America and as much in the rest of the world. The author entered the flotation picture only after the swing from oil flotation to soluble collectors had been well accomplished and the theories built around “oil” had been adapted to the new reagents. Perhaps this excuses his lack of appreciation of the earlier work. The importance of contact angle measurements is emphasized, but the author does not credit T. J. Hoover, who wrote the very first book on flotation nearly thirty years ago, with giving like emphasis. Methods of measurement in Hoover’s day were not so elegant as the present ones and did not tell us as much. On the other hand, credit is claimed for Bradford in first activating sphalerite for flotation by treatment with copper sulfate. Bradford has an Australian patent dated 1913 and this would appear to justify the claim. Nevertheless, the American J. F. Myers and his associates made their separate discovery in Tennessee in July, 1914, and put it into commercial practice. Their historic bronze-slide testing machine gave better results than the commercial wood and iron machine and led to its widespread commercial use in the United States with no knowledge of the existence of the Bradford patent. The connection with flocculation of the floated mineral with good conditions of flotation is credited to Sulman (1919) and Edser (1922) on pages 26, 146, and 301. Closer study of the literature would reveal that in America Bancroft and Van Arsdale were making these observations in 1916-17. The author states in oracular fashion that flocculation of the floated minerals is only a concomitant to and not a necessary antecedent t o flotation. He says that mineral particles clinging to air bubbles give pseudo-floccules. The reviewer knows that the quality of a good practical working froth of just the right volume and lasting just long enough to get out of the machine is quite closely connected with flocculation condition in the froth, and the author’s
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review of the paper stating these facts has missed the point. I t is agreed that proper preparation of an ore pulp involves gangue dispersion to release valuable minerals from complex floccules and to remove slime coatings from mineral surfaces. Thereafter the attempt is to attain selective flocculation even though nothing but “pseudofloccules” might be formed. The condition of flocculation is the beginning of water repellance. The final chapter of the book is on electrical theories of flotation and is the finest thing yet written on this subject. I t recalls the suggestion by the present reviewer made in 1914 that a study should be made of surface charges of suspended particles in their relation to flotation. Swarms of tyros sought to climb enthusiastically onto the electrical bandwagon, only to have i t break down. A disgraceful series of incompetent papers was written. Wark points out the true nature of the electrokinetic potential (a term of recent coinage) but draws an incomprehensible conclusion that, because an air bubble when i t attaches itself to a mineral particle displaces the film of water on a portion of the mineral surface, only the electrochemical potential is of importance. Surface energy simply must have electrical manifestations and, without getting into the hen-and-egg argument, the reviewer must insist that we are not through with “electrical” theories. The non-sulfide and non-metallic minerals are mentioned casually in many places but emphasis is given to flotation of sulfide minerals. Too little is known to permit the author to discourse extensively on the non-metallics. Flotation reagents are classed as frothers, collectors, activators, and depressants. Modifiers and dispersants are rejected aa unnecessary. The reviewer cannot agree. If a dispersant causes removal of a slime coating, the resulting flotation cannot be said to be due t o activation by the dispersant; the latter removed an impediment that was in the way of the true activator. Incidentally, no mention is made of the original classification of frothers and collectors that seems to have come from the group a t the Mellon Institute backed by J. M. Callow in 1915-17. An exceedingly useful book has been presented and the reviewer is justified in stating that one of the brightest stars has flashed into the flotation firmament. ‘Dr. Wark should be encouraged to continue his excellent work. OLIVERC. RALSTON. Inorganic Colloid Chemistry. VoZ. I I I . The Colloidal Salts. By H. B. WEISER. viii + 473 pp. New York: John Wiley and Sons, Inc., 1938. Price: $6.00. This volume completes Professor Weiser’s important work on the colloid chemistry of inorganic substances. The book gives an excellent summary of the recent work in the borderline field between the colloidal state of salts and their precipitated form or macroscopic state. The subject falls rather naturally into five parts, and the author considers the colloidal ( I ) sulfates, (8) halides, (3) sulfides, (4) ferrocyanides and ferricyanides, and (6) silicates in the order named. The section on sulfates also includes a chapter on carbonates, phosphates, chromates, and arsenates. Throughout the book the importance of the adsorption of many different kinds of ions is stressed. This leads to discussions of mechanisms of adsorption, electrical effects, stability, sensitization, coagulation, contamination of precipitates, adsorption of indicators, etc. Thus a good deal of the colloidal chemistry of sols is presented whenever the author is able to connect i t with the results of studies on the salt under consideration. In addition, the important bearing which much of the work in this field has on analytical chemistry is emphasized. The value of some of these materials in the industrial field and in everyday life is shown by consideration of the setting of gypsum, and the preparation and properties of lithopone. Separate chapters are devoted to (1) the silver halides in photography, (8) inorganic soil
