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NEW BOOKS The Metallography of Steel and Cast Iron. By Henry M . Howe. 26 x 20 cm; 641. New York: McGraw-Hill Book Company, Inc. 1916. Price: $10.00. In the preface the author says: “This volume consists of two distinct parts, an introduction to the new science of microscopic metallography, as applied to steel and to cast iron, and an extended study of the very new branch of that science, the mechanism of plastic deformation. It is through the application of the principles of these subjects that the great advances in the metallurgy of iron and steel are to be expected. The mechanism of deformation has The been before us so little that a word as to its importance may not be amiss. usefulness of steel really results from its resistance to deformation, and its power to endure limited plastic deformation. Hence a knowledge of the mechanism of this deformation and of the way in which steel in part resists deformation and in part accommodates itself to it, may in time disclose to us the essence of its power of resistance and accommodation. To understand this essence is to be the better prepared to approach the problem of fitting the metal for its service to our race, not empirically alone but also scientifically.” “Greatly as steel and cast iron differ from each other in manufacture, properties, and application, they form for the metallographist two conterminous divisions of a single series, so closely united that, for the purposes of a general survey, they may well be studied together. Partly on this account, and partly because metallography seems to me to hold out even greater promise to the iron founder than to the steel maker, I have devoted a considerable fraction of this work to the metallography of cast iron. I find strong reason to hope that the intelligent application of metallography may succeed in improving the properties of cast iron to such a degree as to broaden its application greatly. Indeed, a relatively small degree of improvement might well lead to a disproportionate broadening. That so little has been done intelligently to improve the properties of this product by applying metallography to it can be explained in part by the extreme complexity of this branch of the subject, and in part by the usually slighter technical training of the iron founder than of the steel maker. But that so little has been done, far from disproving, tends rather to suggest that much remains to be done, and to add to the attraction of this field, as yet only roughly surveyed.” The subject is treated under the general headings : introduction; thoughts on the permanence of our supply of iron; outline of the classification and manufacture of iron and steel; classification and nomenclature; outline of the constitution of iron; sodium nitrate-water diagram; introduction to the carboniron diagram (cementite-austenite or metastable form, the transformation of steel, the transformations in cast iron) ; graphitization; the phase rule; evidence that the structure of metals is crystalline; general considerations of deformation ; specific deformation, slipbands ; silhouettes ; discussion of slipbands; Beilby’s amorphous theory; plastic def ormation in steel i t w i n s ; the Keumann bands or mechanical twins in ferrite; mechanism of twinning; the X bands; the deformation lines in Hadfield’s austenitic manganese steel; is there fluid as well as crystalline motion in metals? ; inter-granular and trans-crys-

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talline rupture; relative preference of the path of rupture for ferrite and pearlite; fracture; ghosts and the other elements of fiber; influence of manufacturing conditions on fiber; certain crystalline intersections. On p. 196 the author summarizes the discussion on hardening. “Apart from hardening by cold deformation, which is generally thought to act by amorphizing part of any ductile metal, there are five distinct methods, three of them dynamic and two static, three involving temperature changes and two a t stationary temperature, of bringing iron to a hard state intermediate between the soft gamma and the softer alpha states. The hardness of mixtures of this hard state with one or both of the soft end states is so great as to indicate that the hardness of the hard state, if i t could be completely isolated, would be some ten times that of alpha iron and far greater than that of gamma. “I infer that this intermediate state is not amorphous iron, first, because this hardening can be induced statically and thus without mechanism capable of causing amorphism; second, because it endures through long heating a t temperatures as high as 800’ (method ( 2 ) ) a t which amorphous iron would become crystalline and fine-grained iron would coarsen and thus reduce its amorphous envelopes to a relatively negligible quantity; and third, because the hardness, for instance, of quenched carbon steel, decreases progressively on the slightest heating, whereas that of iron made amorphous by cold deformation increases on gentle heating, so that the hard constituent of such hardened steel differs strikingly from the amorphous hard constituent of cold deformed iron. “Amorphism as the common cause of hardening by these five methods being thus eliminated, there remain the solution hypothesis that the intermediate hard state is a simple solution in varying proportions of the two end states in each other, the high temperature gamma and the low temperature alpha; and the beta hypothesis that it is a distinct beta state or states of iron, coordinate with the end states gamma and alpha. Gamma iron alone is dense, beta I and I1 alone are hard, and beta I1 and alpha alone are magnetic, both gamma and alpha being isolated easily, but beta thus far always occurring mixed with either gamma or alpha or more often both. “Between these I choose the beta hypothesis confidently, first, because the hardness of the hardened steel is far too great to represent a simple solution of the two soft end states in each other, especially in view of the slight increase of hardness which the dissolving of the glass hard cementite causes in gamma iron, and because this extreme hardness points to the presence of a far harder allotropic variety; second, because the sharpness of the inflection of the curve of the temperature coefficient resistance, and the sharpness of the extinction of magnetism, a t or close to A2, are so marked as to represent an allotropic change here rather than a mere progressive change in the proportions in which alpha and gamma are dissolved in each other; and third, because, for given degree of hardness, the variations in magnetism are far too great to be explained by variations in the.ptoportions of only two substances, gamma and alpha, for such an admixture should, or given hardness, have only one or a t most two relatively fixed degrees of magnetism, whereas the beta hypothesis of one hard mixed with one bulky and one or two magnetic substances might give almost any intermediate combination of hardness and magnetism. This third reason is reinforced by the fact that the variations in the ratio of hardness to

New Books magnetism with varying conditions of hardening are those which should be caused by the greater bulkiness of the beta and alpha than of the gamma state. “Nevertheless, in view of the hardening, slight though it be, of the copper aluminum alloys by quenching from above their transformation range, referable perhaps to the dissolving of the end constituents in each other and perhaps t o amorphism caused by the quenching strains, it may be that, in the hardening of carbon steel by quenching, both solution and amorphism may contribute to the resultant hardening, that solution may in all the other hardening methods, and that amorphism may in all the dynamic methods. “The solution and the amorphous hypotheses, though each fitting some of the facts, yet fail by themselves to explain others. The beta hypothesis thus liberally applied seems to me to fit all the present and intricately related facts, many of them a t first sight contradictory, with a degree of accuracy which justifies us in adopting it provisionally with some confidence for working purposes. “Because the solution of cementite in gamma iron hardens it so little, and because the hardness given by the static methods, which exclude amorphism, is nearly as great as the greatest given by quenching, I infer that the contribution of solution and amorphism to the hardening of steel is of minor importance, and the preservation of much iron in the beta state the dominant cause.” The reviewer believes that it is unfortunate to assume that Fe3C is a metastable phase under all conditions, p. 131. The author adopts Beilby’s theory of amorphous films, pp, 373, 381, though he apparently does not concede all that is claimed for it, p. 498. This is a monumental piece of work and the reproductions of the micrographs are astonishingly well done. Wilder D . Bancroft

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X 16 cm; ;bp. ix 249. Price: $2.50 net.-In the preface to his book the author makes the following observations: “The state of the art of concentrating ores by flotation is not such that a test-book can be said to cover the field with any degree of intensiveness. The process has not been developed sufficiently to provide a basis for a work that will endure for a great length of time without careful, perhaps radical revision. The theory upon which the process operates has not been fully elucidated, and practice has not been so formulated that much forecasting can be indulged in. The probabilities are that flotation is still in its swaddling clothes and the measure of its full growth cannot be even imagined now. That its usefulness will continue to increase for a long time seems unquestionable.” The book is intended primarily for the engineer and mine-operator and it aims accordingly to give a summary of the status of ore-flotation, particblarly as it has been developed in America up to the present. The chapters include a discussion of the patent records, the theory of ore-flotation, oils and their uses, flotation testing, together with numerous detailed descriptions of flotation plants that have been installed in various parts of the world. More than half of the book is taken up by these descriptions. Several statements appearing here and there interested the reviewer. On page 38 the observation is made that sufficiently fine particles in the pulp will aid in producing a froth, having essentiallv the same effect as a colloid present

The Flotation Process. By Herbert A . Megraw.

A7ew York: McGmw-Hill Book Company, Inc., 1916.

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in the oil, which we know aids the formation of air-in-oil foams. The reviewer has noticed this in some experiments of his own, but hitherto has seen no reference to it in any published paper. I t is probable that the solid particles re-enforce the oil film surrounding the air bubbles and help the limited quantity of oil present to spread out over the very large air-water int.erface. * On the same page there are a few interesting remarks on the spreading of ‘‘collecting’’ and “frothing” oils on a water surface. This is a very important point which has been overlooked in the past and careful experiments along this line will undoubtedly produce some valuable results. A foam of value in flotation cannot be obtained unless the oil spreads rapidly and completely. On page .j8 the statement is made that oil in excess tends to destroy the froth. This is interesting in view of the fact that Hardy once observed a maximum irothing action on blowing air through water on the surface of which was spread an extremely thin film of oil. On adding more oil the frothing diminished rapidly. I t all goes back t o the peculiar behavior of oil films on water, a problem that we have got t o straighten out before we can hope to understand all that happens in. the flotation mill. The book as a whole is a useful one. The chapter on flotation oils is written in a distinctly haphazard fashion and statements are repeated in some cases within two or three pages. However. the author is to be congratulated for not having called upon surface tension t o do the many extraordinary things that we have T . R. Briggs had attributed t o i t in recent publications.

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522. General Chemistry. B y Hamilton P. Cady. 21 X 15 cm; p p . a h New York: McGraw-Hill Book Company, Inc., 1916. Price: $2.25 net.-This book is a condensed and simplified form of the author’s inorganic chemistry (17,369). The general arrangement is much the same; the most marked difference from the earlier book is to be found in the treatment of the atomic theory. “The author feels that the recent advances have justified a more unqualified support of this theory than was accorded in the former work. By introducing an experimental conception of molar weights before taking up the chapter on atomic weights, the author feels that he has been able t o develop the conception of atomic weights in a very simple manner from the experimental standpoint. The theory is then brought in as an explanation for the facts previously discussed.” The headings of the chapters are: introduction: units; oxygen; hydrogen; water, combining weights and atomic theory; hydrogen peroxide; chlorine; ionic theory; oxygen compounds of chlorine; bromine, iodine, and fluorine; sulfur; selenium and tellurium; nitrogen, phosphorus; carbon; silicon; boron; the argon group; the metallic elements; the alkali metals; the metals of the alkaline earths; the magnesium sub-group; copper, silver, and gold; group 111;group IV; group V ; group V I ; group VII; group VIII; radio-activity. As an illustration of the difficulty in avoiding mistakes, one may cite the diagram of the Townsend cell, p. 281,which does not agree with the text and which apparently escaped notice for four years in the earlier book. Wilder D. Bancroft