150 exercises are required for covering satisfactorily the whole. course as presented, but a provision is made for employing the book for a shorter course by the omission of certain designated articles and problems that are less important or more difficult than the others. H. L. W. 3. The Determination of Sulphur in Iron and Steel; by H. B. PULSIFER. 8vo, pp. 160. Easton, Pa., 1922 (The Chemical Publishing Company).-The determination discussed in this book is an exceedingly important one, since sulphur has a deleterious effect upon the metals even in small amounts, and small variations in the amounts present may have important effects upon quality. As the total amount of sulphur present, except in certain crude pig-irons, is usually less than 0.100%, and often below 0.010%, the analytical problem is a delicate and difficult one. A vast amount of research has been devoted to methods of making this determination, and an excellent feature of the book under consideration is an extensive and evidently very complete bibliography of the subject, with many interesting comments and citations of results. The bibliography covers practically the whole period of modern chemistry, as it begins with the year 1797. It takes up about two-thirds of the book, and it is not only interesting historically, but it should be of great value to future workers on this problem. The author has made and records here a very large number of sulphur determinations by several methods, and he recommends the use of an "evolution" method, where the sulphur is first converted into hydrogen sulphide by the action of concentrated hydrochloric acid upon the metal in an apparatus of his own modification, then the hydrogen sulphide is absorbed in an ammoniacal solution of cadmium chloride, and after acidifying the latter the sulphur is determined by titration with iodine solution. It does not appear to the reviewer that the author has definitely shown that his preferred method is the most reliable one, and it must be admitted that his results by different methods show unexpectedly wide variations. H. L. W. 4. Organic Chemistry; by VICTOR VON RICHTER. Vol. II. Chemistry of the Carbocyclic Compounds. Translated from the 11th German edition by E. E. FOURNIER D'ALBE. 8vo, pp. 760. Philadelphia, 1922 (P. Blakiston's Son & Co.).—This translation appears ten years later than the corresponding German edition, but it is to be heartily welcomed as a work of much importance to English-reading students of organic chemistry. For many years the various editions of Richter's Organic Chemistry have been very valuable sources of study and reference to advanced students in the subject, as they have given excellent presentations of the theories, as well as descriptions of very large numbers of compounds. Our older chemists will remember that the earlier English translations of the work were made in a very satisfactory way by Dr. Edgar F. Smith of the University of Pennsylvania. At present the work appears in two volumes, the first of which deals with the aliphatic compounds. The recent German editions have been prepared under the direction of Dr. Richard Anschütz of Bonn. H. L. W. 5. Friction and Lubrication.-In discussing lubrication two cases are to be distinguished: (1) When two surfaces are floated apart by a lubricant, static friction is absent and the resistance to motion varies directly as the viscosity of the lubricant. (2) Where two solid surfaces are near enough together so that the friction depends not only upon the lubricant but also upon the chemical nature of the surfaces, the resistance varies as some inverse function of the viscosity of the lubricant. This second case is termed boundary lubrication. It has recently been studied by HARDY and DOUBLEDAY using polished surfaces of steel, glass, and bismuth lubricated with liquids of the paraffine series. To assure definiteness of contact area, one of the surfaces was made of spherical form, and the other a plane. The coefficients of friction were first determined for the "clean" state where all possibly removable impurities had been abstracted. This is to be judged from the fact that the friction has a high and constant value. The variables studied were (a) the weight of the slider, (b) the curvature, (c) the thickness of the layer of the lubricant, (d) the chemical nature of the lubricant and the solids respectively. The authors find that the friction is strictly proportional to the weight or that the coefficient of friction is (a) independent of the weight and (b) of the curvature. In studying (c) three methods of lubrication were adopted: (1) the flooded state, where the slider stood in a pool of the fluid; (2) the primary film. When a drop of lubricant with sensible vapor pressure is placed on a clean plate, although the drop to all appearance remains where placed without change, an invisible film nevertheless spreads so as to cover the whole plate as is evidenced by the fall in friction; (3) lubrication by deposit from the saturated vapor alone. The results showed that the friction was independent of the quantity of lubricant present provided there was enough to cover the surfaces with the invisible primary film. Where the amount was less than this critical value the fall of friction was proportional to the concentration of the molecules in the gaseous phase, indicating that each molecule exerts the same influence as every other. The influence of chemical constitution (d) was found to be unexpectedly simple. If μ denote the coefficient of friction and M the molecular weight, their relation is given by μ = b — a M where a and b are parameters. The parameter a is independent of the nature of the solid faces and depends only on the chemical type of the lubricant, varying from one chemical series to another. The parameter b however depends both upon the chemical series and the nature of the solid face. The interpretation of these results is difficult. The authors do not accept the current view that friction is due to interlocking asperities of molar dimensions but rather depends upon molecular attraction across an interface. If asperities are to be considered they must be the atoms and the molecules of the substances. The effect of a tangential force is not merely to move the atoms and molecules in the tangential plane but also to rotate them. The mental picture which the authors offer is that the primary film of lubricant consists of a single layer of molecules which have been oriented by the attractive fields of the solids so that their long axes are perpendicular to the solid faces. When two such surfaces are brought together the friction represents the maximum tangential stress which can be supported at some median plane of slip which is an imaginary surface parallel to the surface of the solid. This resistance is obviously conditioned by the attractive field of the solids which must vary rapidly along the normal, and also by the nature of the molecular chain of the lubricant used.-Proc. Roy. Soc. 100, 550, 1922. F. E. B. 6. Power Alcohol; by G. W. MONIER-WILLIAMS. Pp. xii, 323. London, 1922 (Henry Frowde and Hodder & Stoughton).—In view of the possible insufficiency of the world's petroleum reserves the investigation of alternative motor fuels is an important subject which is very fully examined in this book. The first chapter passes in review the questions of the supply, the production and the economy of the various motor fuels, and reaches the conclusion that there is strong probability that before many years the supply of gasolene will be permanently unequal to the demand, and that power alcohol has an undoubted future before it as a supplementary if not as a competitive fuel. Chapter 2 discusses the way in which various organic constituents of plants are elaborated, and the chemical processes by which sugars are converted into alcohol by the yeasts. Chapter 3 treats of the raw materials from which fermentation alcohol is produced, namely, plants supplying starch, plants containing ready formed sugars, and cellulose, and also of the commercial processes of mashing, saccharification, fermentation and distillation. Chap ter 4 surveys the more important starch or sugar-bearing raw materials from the point of view of yield, availability and related economy of alcohol production. Chapter 5 is devoted to the commercial treatment of cellulose materials for the production of alcohol. Chapter 6 explains the ways of making synthetic alcohol and its production on a commercial scale. Chapter 7 reviews the methods of denaturation and various matters in connection with excise supervision in Great Britain. Chapter 8 discusses the principles of the internal combustion engine and its efficiency. In Chapter 9 the chemical and physical properties of alcohol are presented in full detail both by tables and by diagrams. Chapter 10 summarizes with considerable detail the results of alcohol-engine tests with regard to performance and efficiency. These compare very favorably with gasolene-engine tests except in the matter of fuel consumption. Apparently the price of alcohol will have to fall considerably below that of gasolene before it can be regarded as a commercial competitor. Another and more promising line of attack on the motor fuel problem is in the direction of mixtures of alcohol with other easily volatile substances such as ether or benzol, or even with gases such as acetylene. The final chapter (11) discusses various proposals of this nature but the subject is too extensive to receive adequate treatment in a book of this character. Appended to each chapter will be found a useful and numerous list of references to the particular topics which have been under discussion. F. E. B. 7. The Journal of Scientific Instruments.-The Institute of Physics (England) in connection with the National Physical Laboratory proposes to publish a journal devoted to the theory, construction and use of instruments as an aid to research in all branches of science and industry. The preliminary number appeared in May. To assure its continued existence a subscription list of about 3,000 is desired. F. E. B. 8. La Théorie Einsteinienne de la Gravitation; by GUSTAVE MIE, translated from the German by J. ROSSIGNOL. Pp. xi, 118. Paris, 1922 (J. Hermann).—This little volume contains a clear and readable exposition of the relativity theory and Einstein's theory of gravitation couched in simple language and free from mathematical symbols. It should appeal to the reader who has a knowledge of the principles and laws underlying the subject of physics, but who is not conversant with the somewhat complicated differential geometry involved in a detailed presentation of the general relativity. The author's emphasis on the philosophical aspects of the subject should make the book particularly interesting to those philosophers who are looking for a clear and simple account of the revolutionary changes in our concepts of space and time which the relativity principle has occasioned. A short mathematical appendix (11 pages) added by the translator presents in condensed form the author's derivation of Einstein's law of gravitation. L. P. II. GEOLOGY AND MINERALOGY. 1. Gravity Anomalies and their Geological Interpretation*.— This article is in part a condensation of a more detailed paper by the same author entitled "Die mediterranen Kettengebirge in ihrer Beziehung zum Gleichgewichtszustande der Erdrinde." (Abh. Sächs. Akad. d. Wiss., Bd. 38, 2. Leipzig, 1020.) The article opens with some general explanations of the formulas for theoretical gravity and of the methods for reducing gravity observations for topography. This opening section contains two or three statements not strictly correct, but these concern matters not generally understood except by specialists in gravity work or in the theory of the figure of the Earth, and do not essentially affect the conclusions reached. The Bouguer anomaly is used throughout the article as a measure of the compensation. A single Bouguer anomaly measures, of course, merely the net effect of the compensation and of the distant topography and affords no clue to the mass of the compensation nor to its situation. Thus no allowance is made by this method for the effect of nearness to the continental shelf, but for nearly all of Europe this effect is practically negligible. The advantages of using Bouguer anomalies are the ease with which they are computed and the fact that they imply no particular depth or distribution of compensation, and that, when gravity stations are sufficiently dense, they lend themselves, according to Prof. Kossmat, to geological interpretation better than the anomalies computed by the isostatic method. The article summarizes the results of Prof. Kossmat's examination of known gravity anomalies in Europe, Asia, Africa and North America. For the last-named the war has evidently prevented him from receiving the more recent publications on the subject. He maintains that mountain chains are not caused by a swelling of the crust in their vicinity but by the folding under tangential pressure of certain weaker portions of the crust. Such a chain is not compensated by itself but only in connection with the neighboring piedmont regions. The additional matter imposed upon a given area by the folding may be partly compensated by the sinking of that area under the additional load. This sinking the author conceives as partly elastic rather than entirely flotational, the substratum being bent under the load. The result is that the compensation is regional rather than local. In regard to the evidence on this subject offered by the 124 stations in the United States, the number treated in U. S. Coast and Geodetic Survey Special Publication No. 12, which evidently * Die Beziehungen zwischen Schweranomalien und Bau der Erdrinde, by Franz Kossmat. Geologische Rundschau, vol. 12, pp. 165-189. 1921. |