NEW BOOKS Flotation. By A. M. GAUDIN. 552 pp.; 145 illustrations; 20 chaphers. New York and London: McGraw-Hill Book Co. Inc., 1932. Price: $6.00. An introduction, written for this book by Dean Theodore J. Hoover, of Stanford University, who wrote the first book on flotation almost twenty-five years ago, states that, LLOne of the outstanding merits of this book is that i t much more fully than any previous attempt gives a practically complete exposition of the scientific principles underlying a process which is treating millions of tons of ore every year.” The author also drew assistance from the other writers of books on flotation, including the present reviewer, who, with the distinguished T. A. Rickard, prepared the second book on flotation about seventeen years ago; the book is dedicated to the author’s former teacher, Professor A. F. Taggart, of Columbia University, who prepared the third major treatise in English on flotation a t a much more recent date. The result of many suggestions and much criticism before printing has justified Hoover’s estimate of the book. Theory, description, practice, economic effects, are all included. While readers of This Journal are not greatly interested in “Pointers on Mill Design,” “Elements of Costs,” or “Machinery,” there are many chapters on the theory of the process and the technical problems in its application which carry a message. With rare exceptions the researchers on flotation as a method of ore concentration have not been physical chemists and were inadequately prepared to study a phenomenon which is essentially a problem in physical chemistry. The author himself is not a physical chemist, but has striven faithfully t o remedy that defect and has called in the help of many physical chemists, so that his theories might have the background least liable t o criticism. The trouble with the periodical literature has been that the physical chemists did not know much about flotation, and the flotation engineers did not know enough physical chemistry. The result has been a flood of near-worthless papers on the theory of the subject. Gaudin’s book goes far toward remedying this defect and starts off with chapters on the following subject: “The Physicochemical Foundations of Flotation,’’ “The Phases in Flotation Systems,” “Colloid Systems,’’ “Flotation Reagents,” and “The Mechanical Aspects of Froth Production.” The physicochemical problem in flotation is first of all to produce a suspension of finely ground ore in water to which is added reagents that will produce froths of the desired consistence and life. Secondly, other reagents must be added which will cause the desired minerals t o cling to the bubble interfaces so that they will concentrate in a froth layer or the upper surface of the ore pulp. From a colloid standpoint it is a problem more or less of differential flocculation, attachment of certain classes of mineral particles t o bubble surfaces being a function of the degree of flocculation of desired minerals and of gangue minerals. To alter the surface films on particles that normally are not easily floated until they are susceptible of flotation concentration is another problem in physical chemistry. This book is a good start in the direction of discarding misapprehensions and misapplications of science to a process whose application in industry long ago outdistanced its scientific explanation. OLIVERC. RALSTON. 129
