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( b ) The dispersing phase is liquid. Gas bubbles in a liquid form foam; liquids in a liquid form a milk; and solids in a liquid form slimes. (c) The dispersing phase is solid. Gas bubbles create a pumice-like structure. Liquids give rise to the entrapped drops so familiar to the mineralogists, while solids give solid mixtures. Pulverulent mixtures of solids do not belong under this head because powders are really solid particles in air or, in other words, dust. So far as one can judge, Ostwald accepts the Brownian movements, p. j42, at their face value. Of course, t h a t is the most natural and obvious thing to do; but the reviewer has always had a sneaking feeling t h a t the particles only danced when some one was looking. The fact t h a t particles have been seen to dance to-day and also ten years ago is no proof t h a t they have been vibrating continuously during those years. The question is whether the particles vibrate because they are in a n inhomogeneous field or because it is their nature to. ITe know t h a t they will march and countermarch under the influence of a n electric current, we know t h a t they are electrically charged, and we know t h a t they are in a n inhomogeneous field all the time t h a t we watch them; but we do not know as yet whether the actual motion is due entirely to the inhomogeneity of the field or not. Ostmald looks upon the calculations of Einstein and of Smoluchowski as final, in view of the experiments of Svedberg; but a n elaborate mathematical calculation is a thing to be tested very carefully. Tl'ilder D. Bancrojt General Chemistry for Colleges. B y Alexaltder Smith. 13 X ZI cm; 529. -Ye= I'ork: The Centur3J Co., 1908.--"The present Tvork differs from the Author's Introduction to General Inorganic Chemistry, in being intended for pupils who can devote less time to the study of the science, a n d whose needs can be satisfied by a less extensive course. It resembles the larger work in the arrangement of the contents and in the general method of treatment. The matter, and particularly the theoretical matter, however, has been simplified and has been confined strictly to the most fundamental topics. Such parts of the theory, as are thus given, are presented with the same fullness as before, and are illustrated and applied with all the persistence needed to insure full apprehension and, ultimately, spontaneous employment by the student. Such parts as could not be treated in this way, within the limits set by the plan of the book, have been omitted." One of the problems confronting every teacher of elementary chemistry is as t o the amount of physical chemistry to be introduced into such a course. The answer to the problem depends largely on the amount of physical chemistry which the teacher happens to know. Consequently, we are not surprised t o find a lot of it in this book. In the chapter on solution, the subheads are: general properties of solutions; the scope of the word; limits of solubility; recognition and measurement of solubility: terminology; solution, one of the physical states of aggregation of matter; kinetic-molecular hypothesis applied to the state of solution; kineticmolecular hypothesis applied to the process of solution; independent solubility; two immiscible solvents and law of partition; influence of temperature on solubility; equilibrium in a saturated solution.
p p . xiii
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I n the chapter on chemical equilibrium, the subheads are: reversible actions; kinetic explanation; chemical equilibrium and its characteristics; the influence of temperature; the influence of concentration; formulation of the lan- of molecular concentration; the forward action in homogeneous and inhomogeneous systems; the reverse action and displacement of equilibrium. I n the chapter on dissociation, the subheads are: some characteristic properties of acids, bases, and salts, shown in aqueous solution; freezing-points of solutions; laws of freezing-point depression; freezing-points and dissociation in solution; the constitution of solutions of acids, bases, and salts. I n the chapter on ionization, the subheads are: introductory; non-electrolytes; chemical changes taking place a t the electrodes during electrolysis; ionic migration; the hypothesis of ions; application to the explanation of electrolysis; difficulties presented by this hypothesis; risum6 and nomenclature; ionic equilibrium ; applications to the interpretation of conductivity measurements; constitution of solutions of ionogens; relation of ionization to chemical activity. I n the chapter on ionic substances and their interaction, the subheads are: mixed ionogens and double salts; the kinds of ionic substances furnished by ionogens; ionic equilibrium with a single ionogen; displacement of ionic equilibria; double decomposition in solution; precipitation; neutralization; acidimetry and alkalimetry; indicators; displacement and the electromotive series; non-ionic modes of forming ionogens. Scattered through the other chapters are such things as the solubility product, precipitation by a common ion, increase of solubility when a complex salt is formed, etc., etc. From all this it is easy to see that the enthusiastic freshman is expected to learn a good deal of physical chemistry. TT’hether he can digest so much so early in his chemical studies is a matter to be decided experimentally. Presumably, it depends very much on the teacher. On p. 410, there is a n objectionable phrase where the author speaks of “a current of less than 0.j volt.” The reviewer feels also that a more sparing use of the kinetic hypothesis would be advantageous; but this is a matter of taste. In most respects, the book is an admirable one, concise and clear. TT-ildcr D . Bancuojt Exercises in Elementary Quantitative Chemical Analysis. For Students BJ’ d z a r i a h T h o m a s Lwicolit and J a m e s Henri TI‘-altort. 15 X 2 2 cm; pp. xiiz 218. S e w I-ork: T h e AIIacmillan C o m p a n y , 1907. Price: $ r . j o net.-“Owing to the groiving demand for quantitative analytical chemistry by those engaged in the study of agriculture, it seemed t o the authors t h a t the presentation of the fundamental methods of agricultural analysis as carried out in the laboratories of the American Experiment Stations would be desirable. While this book is designed primarily as an elementary quantitative guide for the use of agricultural students, it may also be used for the work in general elementary quantitative analysis.” The book is divided into five sections: introduction; gravimetric analysis; volumetric analysis; agricultural analysis; stoichiometry. Under agricultural analysis, are given methods for analyzing milk, butter, cereals and feeding materials, fertilizers, and soils. The directions are clear, and the book should prove 11-ilderD. Bawcvojt serviceable to those for whom it is written. of Agriculture.
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