THE ANALYST. 325 REVIEWS. A COMPENDIUM OF CHEMISTRY, INCLUDING GENERAL, INORGANIC, AND ORG~NIC CHEMISTRY. By Dr. CARL ARNOLD. Translated by Dr. J. A. MANDEL. (London : Chapman and Hall. This work, which is a translation of Professor Arnold’s ‘( Repetitorium der Chemie,” contains some 570 pages of reading matter, in which the author has contrived to embody a large mass of information probably in as satisfactory a manner as is possible in, for such a wide subject, so limited a space. The information given is accurate, also well up to date, as is especially shown in the chapters devoted to physical chemistry. The book is well printed, commendably free from typo- graphical errors, and contains a copious index. The work has had a large circulation in Germany, having reached its eighth edition, hence it must have a large sphere of usefulness.The information given is, however, hardly detailed enough for the advanced chemist, and the book would be by no means easy reading for the novice. The translator has done his part admirably. Price 15s. net,) W. J. S. THE OCCURREKCE OF ALUMINIUM IN VEGETABLE AND ANIMAL PRODUCTS, AND IN NATURAL WATEBS. By Drs. C. F. LANGWORTHY and P. T. AUSTIN. (London : Chapman and Hall.) This is an exhaustive compilation and reproduction in a condensed form of the numerous articles which have appeared for some years past in the various chemical and food journals, official reports, etc., and certainly is a monument to the authors’ patience and perseverance. The book cannot fail to be extremely useful to those interested in the subjecli on which it treats.The printing is good, the work has been carefully revised, and is furnished with an index occupying a fifth of the whole volume. W. J. S.326 THE ANALYST. THERMODYNAMICS AND CHEMISTRY. By P. DUHERI. Translated by GEORGE K. BURGESS. (London: Chapman and Hall, Ltd. 1903.) Price 17s. net. Pp. xxi + 445. The day of rule-of-thumb methods and empirical reactions in analytical chemistry fast drawing to a close; the modern analyst is not satisfied wit,h the knowledge that a reaction takes place, but must needs find out under what conditions it is complete, and how it is eEected by the presence of (‘ inert ” bodies. Thermodynamics, therefore, is a st.udy which should not be neglected. As this science concerns change of state, it has usually been treated of by that branch of mathematics which enables change to be expressed in a simple manner-the infinitesimal calculus ; and a want of training in higher mathematics has deterred many from familiarizing themselves with modern thermodynamic theories.This work is written for the non-mathematical student; in fact, the author states in the preface that he has supposed on the part of the reader no knowledge beyond that possessed by the graduate of a good high-school. I t is a little doubtful wh‘ether the author can be considered to have achieved entire success in his en- deavour to free the ideas of thermodynamics from all mathematical complications, for not only does the work bristle with formullfit, but these are used to define terms used.The differential calculus is not used, but the idea of a diflerential is brought in as a tangent to a curve, and it is not made quite plain why the tangent is introduced. If a page or two at the commencement of the work had been devoted to explaining the first principles of the differential calculus, and especially that if a law is ex- pressed by an equation or a curve, the differential expresses rate of change, many points would have been simplified. The author has assumed that the reader has a knowledge of co-ordinate geometry of three dimensions, which is not always taught at gnglish high-schools. The reader must therefore be prepared to use a certain amount of math em at ic s . The first five chapters are introductory; the first treats of work, energy, and equilibrium, while in the second the ideas are applied to heat; the next three are on chemical calorimetry and equilibrium and the principles of chemical statics.The sixth chapter is on the phase rule of J . Willard Gibbs, which treats of the relation between the number of components and the number of phases of a system; this rule, which is purely mathematical, is treated of with a minimum of mathematics, and in a manner which makes it plain to the careful reader. In succeeding chapters the various kinds of systems are described and illustrated by examples ; thus multi- variant systems-ic., those in which there are more components than phases-are illustrated by ternary alloys and solutions of several salts ; monovariant systems, those which have one phase more than there are components, by, among other illus- trations, the variation of fusing point with pressure ; triple points--i.c., points whero a substance csn exist in equilibrium in three phases-are explained, as well as the analogous multiple points of systems containing more than one component.Considerable space is devoted to mixed crystals, eutectic points, and critical states, and the chemical mechanics of perfect gases is discussed. The chapters on false equilibrium, and on chemical dynamics and explosions, which conclude the work,THE ANALYST. 327 are of considerable interest and importance, and should have practical bearing on analytical work, I t is annoying to constantly find letters dropped out in the printing, and to meet with so much repetition ; for instance, the heading of Section 322 is ‘‘ Every state of false equilibrium which is not limiting is indifferent,” a self-evident proposition ; yet this is discussed and explained by putting it into other words, and, finally, the proposition is again stated; all this takes up nearly half a page.The author uses the value 2.325 in many of his formulif?, as well as its reciprocal 0.4301 ; these are evidently the value of log. 10 and the modulus of common logarithms, which should be 2,3026 and 0.4343 respectively. The spelling of some chemical names-e.g., butric acid, propionitrite, benzine, and methylethylcetone-is not in accord with the usual methods. While the book is unnecessarily tedious, and requires very careful study and constant reference to formuk given in the earlier chapters, it is one that will repay the time spent in mastering its contents, and the earnest student will gain much valuable information and have his mind widened by reading it.H. D. R. THE EXAMINATION OF WATERS AND WATEIC-SUPPLIES. By J. C. THRESH, D.Sc, The interpretation of the results of water analyses is not to be undertaken lightly or without patient study, and the work now under review will be found very helpful to young practitioners, while most analysts of riper experience will find in its four hundred odd pages much to interest them, and will be glad to possess it as a book of reference, if only for the sake of the many illustrative analyses of waters from different sources which are here brought together. The work is divided into three parts, of which the first deals with the sources from which water is derived.Without undervaluing the information yielded by the mere analysis or examination of the water itself, the author strongly urges that the examination of its source is even of greater importance, and is sometimes absolutely essential to a right interpretation of the results obtained in the laboratory. This portion of the work deals with the geology of water-bearing strata, and discusses deep and shallow wells, surface-water supplies, rivers and streams, and includes a chapter on storage and distribution, written from a sanitary rather than from an analytical standpoint, The second part deals with the interpretation of the results of physical, chemical, microscopical, and bacteriological examinations ; while the third part is devoted to a detailed discussion of the collection of samples and of the various methods of analysis, whether for ordinary sanitary purposes or of a more complete character, including the determination of gaseous as well as saline contents.I n this section considerable space is given to methods of bacteriological and microscopical examination. Under the heading of “Nitratcs” two reduction methods by the copper-zinc couple are described-namely, reduction in slightly acid and in alkaline solution respectively. The indigo process is described, but the author only gives it half-hearted commendation, saying that he prefers the copper-zinc couple process. When the (Lond.), M.D. (Vict.), D.P.H. (Camb.). (London : J. and A. Churchill.)328 THE ANALYST.accurate determination of very minute quantities of nitrate is concerned, the author is probably right. I t should be observed, however, that the instructions given both for standardizing the indigo solution and for applying it seem insufficient for working the process with the simplicity, rapidity, and degree of accuracy of which it is capable. The phenol-sulphonic method of converting nitric acid into picric acid is described, but not recommended. The Crum process, singularly enough, is not given. The author mentions various modifications introduced from time to time in Forcham'mer's method for (' oxygen absorbed by oxidizable organic matter." Prob- ably most analysts in this country are in the habit of keeping the water, after adding the permanganate, for four hours at a temperature of 80" F., in accordance with the recommendation of the Water Committee of the Society of Public Analysts in 1881 (see ANALYST, vol.vi., 1881). Dr. Thresh prefers a temperature of 98" F., because that is the temperature of the ordinary warm incubator now found in most laboratories. Where, however, temperature is a purely arbitrary matter, but where uniformity is essentially desirable for the comparison of results, it seems a pity, on the mere ground of slight extra convenience, to introduce yet another alteration. The author only casually alludes to the fifteen minutes' period. Probably most public analysts, still following the recommendations of the Water Committee of 1881, are in the habit of making two determinations of oxygen absorbed-one after a period of four hours, and the other after a period of only fifteen minutes-attaching considerable significance to the ratio between the matter so readily oxidizable as to consume oxygen in the shorter period as compared with that oxidized during the main period of four hours. Referring to the opinion now largely held that a bacteriological examination is more important than a chemical analysis, the author observes that this is undoubtedly true in certain cases, but not in all, and that, while a properly made bacteriological examination may often afford indications of pollution which no chemical analysis can detect, yet the inferences drawn from the results of many so-called bacteriological examinations are often as fallacious as those derived from the results of chemical analyses.He observes that when we find that waters used for long periods by large communities are condemned by bacteriologists as being dangerously polluted, and that the results obtained from the same water by different bacteriologists differ to an extent that is impossible in a chemical analysis, our -faith in bacteriological examina- tions is somewhat shaken ; and that in any case a proper bacteriological examination is far more tedious and troublesome to perform than a chemical analysis, while the results are even more difficult to correctly interpret. The book is well printed in large, clear type, and is copiously illustrated. B. D. JUST before going to press we have received the painful intelligence that our esteemed colleague, Mr. William Chattaway, died suddenly on Friday night, Oct. 7, after a surgical operation. This sad announcement will, me feel sure, be read with universal regret.