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NEW BOOKS Nucleic Acids. By P . A . Leuene and L . W . Bass. 83 X 16 cm; p p . 337. New York: Chemical CakZbg Company, 1951. Price: 84.60. This is one of the American Society Monographs. In the preface the authors say: “The chemistry of nucleic acids can be summed up very briefly. Indeed, a few graphic formulas which need not fill even a single printed page might suffice to express the entire store of our present-day knowledge on the subject. Yet a detailed formula expressing the arrangements of all the atoms entering in the structure of the molecule of nucleic acids is the result of the combined labors of many chemists, the list of whom is headed by Scheele, who w m born in 1742 and died in 1786. Somehow, every point in the structure of nucleic acids was reached with great difficulty by the paths of error and controversy. Theories had been advanced and had been abandoned but even the errors often led to true progress and it would be an injustice to many if the monograph contained only the views that seem correct today. Hence, the historical method of discussion was adopted in this monograph. I t was hoped that this method would lead to an unbiased presentation of the material; yet we fear that unintentionally some contributions may have been overlooked”, p. 7. The book is divided into two parts, entitled Components of the Nucleic Acids and The Nucleic Acids. I n Part I the chapters are: sugars, imines, imido esters, and imidazols; pyrimidines; uric acid and purine; purine bases; nucleosides; and nucleotides. In Part I1 the chapters are: the discovery of nucleic acids and of their components; structure of nucleic acids; nucleic acids of higher order; nucleases. “Imperfect as is the present-day knowledge of the chemistry of nucleic acids, yet it is able to disclose much of the mystery of their biological synthesis and of their degradation. I n its simplest form nucleic acid is an ester of phosphoric acid and an organic radicle, the latter consisting of a sugar and a nitrogenous component which is a cyclic derivative of urea. The moment chemistry has succeeded in formulating nucleic acid in these terms, it has indicated the way of its formation from carbonic acid, ammonia, and phosphoric acid. I t has long been known that the plant is capable of reducing carbonic acid to formaldehyde and of condensing this into sugar. It is also long known that urea can be derived from carbonic acid and ammonia; in fact, urea is a partially ammonized carbonic acid. As an aquoammono derivative of an organic acid, urea represents a particular substance of a large group of analogous substances widely distributed in animal and plant tissues. “The one peculiarity that is common to all substances of this group is the readiness with which they s d e r intramolecular rearrangements under the influence of external conditions. Every rearrangement naturally leads to an alteration in the chemical functions of the substance. I n the living organism every change in chemical function may and perhaps always does lead to a change in biological function. If for a moment one stops to think that nearly every biologically important organic molecule bontains at least one and most frequently many such dynamic groups, and that the number of them in a single cell is beyond count, he will realize what a sensitive instrument the cell is. If he will further bear in mind that most of the changes here referred to are reversible, and that even in a simple solution of a single substance the ratio between the two forms can be discovered only with great difficulty, he will realize the obstacles that the biologist must encounter on his way when he attempts to correlate biological function with chemical change,” p. 12. On p. 41 the authors give graphic formulas for the enol and the keto form of uracil; but they do not point out that the enol form would add one hydrogen chloridestoichiometrically and the keto form none. Since uracil does add one hydrogen chloride stoichiometrically the solid cannot be the keto form. This does not necessarily have the enol form as mitten because there are other possibilities not discussed by Levene and Bass. On p. 63 they say that uracil does not combine with acids. “The free base [cytosine] crystallizes out in bright platelets with mother-of-pearl luster,” P. 57.

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“The observations of Brugnatelli and of R o u t are the last made in the period of the primitive phase of organic chemistry. They have a more or less casual character. By itself, the discovery of a new substance waa in those days a great event, and to establish connection between the newly discovered compound and the parent substance was beyond the power of chemistry at that time. The search for new substances rather than the finding of relationships was the dominant incentive even in the following period when the chemist was already in possession of quantitative analytical methods. This peculiarity comes to light very strikingly when one reads side by side the classical contributions of Wohler and Liebig and of Baeyer.’ It will be seen later that Baeyer in a way may be regarded aa the interpreter of the findings of Wohler and Liebig, a relationship which in no way detracts from the importance or from the value of Baeyer’s contributions,” p. 78. “The workers who were principal figures in the development of uric acid chemistry, namely, Liebig and Wohler and Baeyer, were inclined to derive the substance from aminobarbituric acid. It is poeaible that the formulation of Medicus was inspired by what may be termed the instinctive feeling of the great chemist. The graphic formulas of Medicus and of Fittig, however, were no more than probab es, no more than hypotheses, and were not theories rigorously,” p. 88. “One might have said that .the syntheses of uric acid by Behrend and Roosen and by Fischer established the structure of uric acid sufficiently well to make additional evidence in favor of the Medicus formula superfluous. In recent years, however, there have come to light many instances of migration of groups in course of a synthesis, and therefore any theory of structures established on synthesis alone gains in value when it is substantiated by some other independent methods. “Thus, to sum up, the contributions of Fischer to the theory of the structure of uric acid are the following: He accomplished a synthesis of uric acid by a method that indicates a union of the second urea rest to carbon atoms (4) and ( 5 ) of the pyrimidine nucleus. He synthesized all the mono-, di-, and trimethyl derivatives that are postulated by the theory of structure expressed by the formula of Medicus. He demonstrated the presence of a double bond between carbon atoms (4) and ( 5 ) as required by this theory. He converted uric acid into trichloropurine, which is theoretically possible only when uric acid has the structure assigned to it by the same theory. And, finally, he converted uric acid into purine, the nucleus of all naturally occurring substances related to uric acid,” p. 93. “The significance of the nucleosides in the development of the theory of the structure of nucleic acids was manifold. Their discovery a t once ended the dispute as to whether the bases in the molecule of nucleic acid are attached to the sugar or to the phosphoric acid. They furnished a rational explanation of many physical and chemical properties of the simple and complex nucleic acids. One of the most important practical interests of these substances lies in the fact that through them it was possible to isolate the sugars of the nucleic acids in crystalline form and thus to reveal the structure of these peculiar sugars. Thus far they have not been found in any other combination save in connection with nucleic acids. “The name ‘nucleosides’ was aeaigned to the substances of this group for the reason that, on one hand, they contain sugar in a glucosidic union, and, on the other, the substances linked to the sugars are nuclein bases. It is evident that the physical and chemical properties of each individual nucleoside are the resultants of the individual peculiarities of the sugar and of those of the base. In the discussion of their properties, nucleosides may be classified, therefore, according to either the sugar or the base. It may be expedient, however, to classify them fist according to their sugar and then subdivide each group according to the base. The principd reason for this preference lies in the fact that each of the complex nucleic acids contains only one sugar and four bases, and, furthermore, for the reason that ribose characterizes the plant nucleic acid and desoxyribose the thymonucleic acid. Thus, in a way, the sugar always reveals the origin of the nucleoside; the base in some cases only. “Thus far there have been discovered in nature four different sugars linked in glucosidic union to nuclein bases, namely, ribose, desoxypentose, methylthiopentose, and glucose.

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Each of the latter two sugars has been found in a single nucleoside. The following four types will be discussed, and -,hen necessary, they will be subdivided according to the type of the base. I. Ribosides. a. Purine ribosides. b. Pyrimidine ribosides. 2. Ribodesosides. a. Purine ribodesosides. b. Pyrimidine ribodesosides. 3. Adenine methylthiopentoside. 4. Pyrimidine hexoside (glucoside). “This classification refers to the naturally occurring nucleosides only. Synthetic nucleosides have been prepared from several common sugars, namely, from derivatives of glucose, galactose, rhamnose, arabinose, xylose, and ribose. All these synthetic nucleosides will be discussed in the section on ribosides according to the component base. The reason for this mangement lies in the fact that the details of the structure of nucleosides were worked out on the ribosides, which are by far the most accessible and which chronologically were the f i s t to be obtained from nucleic acids,” p. 126. “In justice to Haiser and Wenzel it must be said that their conclusion was partly due to the fact that they had relied upon the data of Neuberg on the properties of the phenylosazone of the sugar obtained from inosine. Later they took the mixed melting-point of the two benzylphenylhydrazones, namely, of lyxose and of the sugar from inosinic acid. The individual hydrazones had nearly identical melting-points, that of lyxose melting at 127°C. and the other a t 129°C. The mixed melting-point, however, was 40’ below the values of the individual compounds. Furthermore, they found that the p-bromophenylhydrazone of the sugar from inosinic acid has the same properties as van Ekenstein and Blanksma described for ribose. The authors then accepted the conclusion of Levene and Jacobs on the ribose configuration of the sugar,” p. 134. “This gelatinization of guanylic acid requires special discussion. I t is not caused by the colloidal nature of the acid, but is due to the presence in its molecule of guanosine, which, in the presence of impurities, settles out of aqueous solution in gel form. This peculiarity was observed by Levene and Jacobs in their early work on guanylic acid. It was then stated that the product of neutral hydrolysis of nucleic acid on cooling turned into a semisolid gel. Very minute quantities of mineral impurities suffice to bring about gelatinization. I n excess of alkali, this gel is soluble. The gelatinization of guanylic acid also depends on the presence of a small quantity of sodium or potassium ions. Feulgen later dwelt very exhaustively on the gelatinizing property of the acid sodium salt of guanylic acid. Indeed, Levene and Jacobs in 1912 showed that when the gelatinizing guanylic acid is purified through conversion into the mercury salt, the free guanylic acid obtained from it does not gelatinize but forms a nicely crystalline brucine salt. This investigation of Levene and Jacobs is important for still another reason, namely, it introduced for the fist time the method of purification of nucleotides through fractional crystallization of their brucine salts. The method has been in general use since that date,” p. zoo. “In 1869 Miescher sent to Felix Hoppe-Seyler, at the time Professor at Tubingen, a manuscript announcing the separation of the nuclear substance from the other constituents of the cells; to this substance he assigned the term ‘nuclein’. This discovery was not a matter of mere chance or of good fortune, as discoveries often are, but was the result of conscious and sustained effort to find a chemical explanation of morphological and physiological observations,” p. 240. “The properties of this substance seemed very startling. It had stronger acidic properties than proteins were known to possess. It was soluble in dilute alkalies and insoluble in dilute acids. It was insoluble in water and in organic solvents. In its solubility it resembled mucin but it was not mucin. It did not contain sulfur but did contain a considerable proportion of phosphorus. At the time the only known phosphorus-containing organic component of tissues was lecithin,” p. 241.

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“Under the influence of Fischer’s discovery of glucal, which originally was supposed to possess the property of ordinary aldehydes to restore the color of a fuchsine solution decolorized by sulfurous acid, Feulgen attributed the glucal structure to the sugar of thymonucleic acid. Somewhat later, however, Fischer, Bergmann, and Schotte found that purified glucal does not possess the properties of simple aldehydes and that the reaction attributed to it wa,s due to impurities. This finding naturally disposed of the theory of Feulgen, and accordingly the question arose whether the Schiff reaction obtainable with the neutralized hydrolysate of thymonucleic acid was due to a secondary decomposition product or actually to the sugar present in it. Indeed Steudel and Peiser insisted that both tests discovered by Feulgen were due not to the sugar component but to traces of furfural which were formed on hydrolysis of nucleic acid, and that the sugar itself might be simply glucose, the queer behavior of which could be explained by its f i m union with the phosphoric acid,” p. 259. “In 1912, however, Levene and Jacobs stated that in their belief the peculiarities of the conduct of thymonucleic acid were attributable to the unusual instability of the sugar. This has been the firm conviction of the senior writer of this monograph since 1909,for his experiments on plant nucleic acid were always paralleled by experiments on thymonucleic acid. Because of this conviction he initiated in cooperation with Medigreceanu, a detailed study of the nucleoclastic enzymes, and as a result of this investigation it was possible to locate in the intestinal juice an enzyme capable of cleaving nucleotides to the stage of nucleosides only. This finding was the incentive for the work that led finally in 1929 to the isolation of the desoxypentose nucleoside by Levene and London. Through the action of gaatrointestinal secretions on a solution of thymonucleic acid, and through the resulting isolation of the nucleosides, the mode of union between sugar and base has been established,” p. 264. “As yet it is not certain whether nucleoproteins are protein salts of nucleic acids or more stable substances derived from nucleic acids through loss of water (esters or acid amides). On this knowledge will depend the significance of the observations of Hammarsten for the biological functions of the cell. I t must be admitted, however, that in the fish sperm the nucleic acid is present in an ionizable combination with protoamine,” p. 293. “Proteins with an isoelectric point at pH 4.7 combine with thymonucleic acid more readily in the region of the first two dissociation constants of the acid. This behavior is not easily understandable in view of the fact that the values of the f i s t four dissociation constants of nucleic acids are of the same order of magnitude,” p. 293. “In the preceding chapters reference has been made to the r61e of enzymes in the evolution of the present-day knowledge of the structure of nucleic acids. Needless to say, the chapter on nucleic acids is not the only one in chemistry in which enzymes are employed aa chemical reagents. In fact, it is certain that in the future enzymes will be found to be among the most useful reagents in the study of the structure of all natural organic substances of high molecular weight, such as starches, proteins, fats, etc. “The knowledge of the existence of nucleases antedates our knowledge of the structure of nucleic acids. On the other hand, it is true that it was the elucidation of the structure of ribonucleotides and ribonucleic acids which made possible the identification and the classification of individual enzymes of the group of nucleases. The familiarity with nucleases, in its turn, made possible the elucidation of the structure of thymonucleic acid,” p. 309. Wilder D. Bannofl

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Physical Chemistry. By L o u i s J. Gillespie. 21 X 14 cm; p p . ix 287. N e w York and London: McGraw- Hill Book Company, 1931. Price: $2.75. In the preface the author says, p. v: “This book has been developed from lecture notes used in a course intended primarily for biological students and given by the author a t the Massachusetts Institute of Technology for the past seven years. . . . Certain subjects that are often included in physical chemistry but are not taken up here are modern atomic theory, crystal structure, and photochemistry. There is no chapter on colloid chemistry, but it is believed that most of the important physical chemistry of colloids is presented, the principal omissions being of a descriptive nature. The subject matter has been thus limited in order to make possible a high degree of unity.”

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The chapters are entitlea: introduction-the phase rule-equilibrium in general; a simple theory of gases; general properties of liquids and solids; surface tension; phase relations with liquids and solids for pure substances; relations of gases to liquids or solids when one or more of the phases is a solution; the measurement of vapor pressuresteam distillation; the vapor pressure of liquid solutions; vapor pressure lowering-boiling point elevation-freezing point depression; osmotic pressure; the colligative properties of sohtions of electrolytes and of non-electrolytes; electrical conductance; theory of the conduction of electricity through aqueous solutions; transference numbers and the mobility of ions; thermodynamics and free energy; electromotive force and free energy; liquid junction potentials-the activity-the influence of pressure and composition of the electrode substance; chemical cells; cells for the determination of hydrogen-ion concentration or activity; the law of mass action; typical applications of the mass action law in terms of concentrations to electrolytes in solution; amphoteric electrolytes; bufIers and titration curves; indicators; Donnan equilibrium, membrane and interfacial potentials; oxidation and reduction potentials; the heat of reaction and the effect of temperature and pressure on chemical equilibrium; the velocity of chemical reactions. “If a wet soluble salt is placed on a blister, the water is ‘drawn out’ from the blister. The blister skin is not very permeable to most salts, but is rather rapidly permeated by water, and the water passes out from a dilute solution within the blister to the concentrated solution about the salt. That this might happen, and not the contrary movement of water, we should infer from the fact that the vapor pressure of water in the concentrated solution is less than that in the dilute solution, so that if blister fluid and saturated salt solution were to be placed in separate containers underneath a hell jar, the water would distill from higher to lower vapor pressure”, p. 78. “Physical chemists usually call the osmotic pressure the osmotic pressure of the solution; biologists often call it more explicitly the osmotic pressure of the dissolved substance that cannot, pass through the membrane. It is often necessary to be explicit,” p. 79. “The osmotic pressure of the colloids of blood serum has been found to be about 30 to 34 mm. of mercury. In earlier work somewhat lower values were found ( 2 5 to 30 mm.). Although the osmotic pressure of the blood has no great significance, it is otherwise with the osmotic pressure of the blood colloids. It is an important task of the kidneys to remove water and many crystalloids from the blood while retaining the albuminous blood colloids. I n the glomerulus of the kidney a filtration occurs, in which colloids are retained and water and crystalloids are permitted to pass. The existence of a more or less perfect semipermeable membrane in the glomerulus is evident. Unless the pressure on the blood entering the glomerulus isgreater than the osmotic pressure of the blood colloids there will be no tendency for the water to leave the colloids and enter the filtrate. The pressure of the blood is normally ample to account for the atration. I n experiments on animals it has been possible to reduce the blood pressure in the renal artery to a value near the osmotic pressure, and when this is done, the secretion of urine Stops. “The variation in blood pressure from artery to vein is also quite enough to be important in determining the interchange of fluid between blood and lymph,” p. 86. “Because in changes a t constant temperature the nature of the intermediate steps is of no importance, there is a definite capacity of a system for doing work in constant-temperature changes of state, which capacity is known as the free energy of Helmholtz, or as the ‘work content.’ The decrease in this capacity is measured by the maximum quantity of work obtainable in the change of state when conducted throughout at constant temperature. “When a change of state occurs a t constant pressure, work may be done in the expansion of the system against the external pressure. It is proved that its magnitude will be given by the product of the pressure times the increase of volume (and it will be negative, if the volume decreases). This work against constant external pressure depends evidently on the initial and final states alone. Hence, since there is a definite capacity of the system for doing work in constant temperature changes of state, there must be, in the case of changes of state at both temperature and constant pressure, a definite capacity of the system for doing work in excess of the work of expansion. This latter capacity is known in America, and to an increasing extent elsewhere, as simply the free energy.” p. 123.

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“The chloranil electrode is coming into use. The solutions are eaturated with both chloranil and its hydroquinone. These two substances do not form an insoluble compound like quinhydrone,” p. 167. “The glass is a glass membrane and very thin, not more than about 0.025 mm. thick. Such membranes were 6rst extensively studied by Haber and Klemenriewicr. Even with the thinnest membranes, an ordinary high sensitivity galvanometer will not receive enough current through the glass membrane to operate satisfactorily, and a quadrant electrometer is generally used, which takes only enough current to charge its plates. Owing to the very high resistance of the cell, the insulation must beextraordinarilyeffectiveso that theelectrometer does not receive any charge from a source other than the cell. Recentlv a new vacuum tube haa been successfully used to replace the quadrant electrometer. “Not all glasses are equally suitable. If the glass has a suitable composition and is in contact with solutions not too alkaline it seems to act a t both surfaces as an electrode reversible to hydrogen ions alone, that is to say, hydrogen ions are somehow absorbed at one surface and delivered a t the other when current is passed without the occurrence of other important changes of Rtate,” p. 169. The pH of water is given, p. 199,as 7.45 a t oo, 7.0 a t 25”,6.15a t 1m0, and 5.7 at 300”. “When the electrochemical process does not involve the hydrogen (or hydroxyl) ion, and likewise the chemical reaction, oxidant to reductant, does not involve hydrogen (or oxygen), then the oxidation potential will depend only on the activities of the oxidant and reductant and not upon the activity of hydrogen ion. When the hydrogen ion is involved, it always acts as an oxidant to increase the oxidation potential. Hence, any solution is likely to be less oxidizing a t higher pH values. “It is clear that measurements of oxidation potential should in any case be accompanied by measurements of pH,” p. 252. “In the formulas for oxidation potential the absolute concentrations of oxidant and reductant do not matter but only their ratio. We may have then a given high level of oxidation produced by a large amount of material, or by a small amount. I n some biological systems the amount of material responsible for the oxidation potential may be of great importance; for instance, bacteria may in their metabolism use up oxidants and thus greatly change the oxidation potential of the medium, if this is the result of small amounts of material. The oxidation potential does not measure the amount of oxidizing or reducing substance, but only the level of oxidation as defined above,” p. 252. “The investigator in pure physical chemistry has never been interested in measurements of electromotive force unless he has known the electrode processes. The biologist also seeks to learn what are the electrode processes back of an oxidation potential, but can afford to attempt to correlate biological phenomena with oxidation potentials even if without hope of discovering the nature of the electrode processes,” p. 253. On p. 20 there is a helpful table giving the constants in an equation of state for various gases. On p. 8 2 it is not true in general that the osmotic pressure for two solutes will be the sum of the osmotic pressures of the solutes taken singly. The relation is a function of the es. Few botanists would now admit that osmotic pressure is one of the important factors in the rise of sap in trees, p. 88. Wilder D. Banmojt

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Spektroskopie der Rbtgenstrahlen. B y M a n n e Siegbahn. 24 X 17 n;pp. vi 675. Berlin: Julius Springer, 1931. Price: 4? marks, bound 49.60 marks. I n reading the second edition of Siegbahn’s “Spectroscopy of X-rays” one has a very vivid impression of the great advances which have been made since the fist edition appeared in 1924,and of the way in which the author and his pupils have continued to lead in this field. This is a book which no one but he could have written so well and it immediately takes its place aa the standard work on X-ray spectra. The subject has grown so rapidly that the present edition runs to more than twice as many pages aa the former. Its pages are packed with information, but the book is very readable because of its excellent arrangement.

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The division into chapters follows in the main the lines of the former edition. They comprise I, Knowledge before Laue’s discovery of Diffraction; 11,X-ray Optics; 111,Technique; IV, Emission Spectra; V, Absorption Spectra; VI, Theory of X-ray spectra; VII, Investigation of the Long-wave Region; VIII, The Continuous Spectrum. The technique of the measurement of X-ray wavelengths has greatly improved. As is well known, the accuracy with which wave-length may be determined in terms of a crystal spacing, and thus compared with each other, is much higher than that with which the crystal constant itself is known, owing to our lack of knowledge of the precise values of atomic constants. It is therefore necessary to define arbitrarily a standard crystal spacing, and refer all X-ray wave-lengths to it. The standard first used was the spacing of planes parallel to the cube face of a rocksalt crystal, which was taken to be primarily 2814.00 X E (2.814wA). Rocksalt is, however, by no means an ideal crystal for the purpose, and the standard now accepted is the spacing of the ( I I I ) planes of calcite, defined to be dip = 3029.04 X E. As an illustration of the increasing accuracy of measurements we may instance progressive determinations of the iron K, doublet Kc,, Kaz Moseley (1914) 1946 Siegbahn & Stenstrom (1916) I932 1928 Siegbahn & Doleysek (1922) 1936.51 1932.30 1936.51 1932.38 L a w (1924) Lareaen (1927 ) 1935.907 1932.066 Ercksson (1928) 1936.012 1932.076 Whereas in the earlier edition a table of wave-lengths for the K, L, and M series of all elements sufficed to summarize our knowledge, so much work on emission spectra has now been done that it is found deairable to accord each element a table of its own. The chapter on emieaion spectra has been expanded to four times ita former size. Certain sections of the book are entirely new, and describe lines of investigation which have been developed since the first edition was written. Most of the familiar optical effects of surface reflection, of refraction, and of diffraction have now been paralleled in the X-ray region. The existence of a refractive index for X-rays slightly less than unity was predicted by Darwin in 1914, and Compton discovered the consequent total external reflection a t a plane surface. The dispersion, or variation of refraction index with wave-length, shows interesting abnormalities in the neighbourhood of an absorption edge which are analogous to optical anomalous dispersion. The refraction of X-rays by a prism, their diffraction by passage through a fine slit, fringes by the Lloyds mirror method, and fringes by reflection a t both surfaces of a thin film, have all been observed. Most important of all, the diffraction of X-rays by a ruled grating, first demonstrated by Compton and Duane, has been used by Siegbahn and his School and by other workers to investigate the range between the X-ray and optical regions with conspicuous success. Chapter VI1 is devoted to this new field. Spectra recently obtained with a curved grating and fine angle of incidence show a wealth of detail in the region 50 A to 500 A which recallsthat of optical spectra. I t is now possible to make precision measurements in the whole range of wave-lengths, the former gap between X-rays and light having been completely bridged. Other new sections deal with the fine structure of absorption edges, the influence of chemical combination on absorption and emieaion spectra, the fine structure and breadth of emission lines. A series of tables are given, of which the most important is a list of the strongest lines arranged in order of wave-length. The extensive literature-index occupies eighty pages, in itself an indication of the vast field which is reviewed. There are separate indices for authors and for subjects. One cannot but be grateful that Professor Siegbahn has found it possible, while engaged so actively in research, to bring up to date his exposition of a subject in which he is so great an authority. L . Bragg.

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Fortschritte der Metallkunde und ihre Anwendungen auf Leichtmetalle: ( A Symposiu?, 39 x 20 n;p p . vi $53. Berlin: Verlag Chemie, 19$1. Price: 16 marks. The title of this publication suggests a volume of delicious reading for the metallurgist, and the presence of such names aa Sachs, Mark, Masing, and Polanyi in the author-index serves to enhance the prospect. The book consists however, of 67 miscellaneous papers contributed to the 36th Congreas of the Deutschen Bunsen-Gesellschaft fiir angewandte physikalische Chemie E. V., of which only about 30 would seem to be directly related to the formula which appears on the cover. “Advances in Physical Metallurgy and their application to the Light Metals” might pass as a translation of the general subject of the Congreas, though it must be admitted that a difficulty has been generally recognised in rendering into English the word “Metallkunde.” Suggestions which have been advanced quite recently to replace the term used above, include such words as “metallics,” “metallosophy” and “metal-lore.’’ Whatever equivalent the English metallurgist might concoct for purposes of translation, however, the general sense of the title would not suggest to him that papers on “The Cyclohexane Problem,” “The Electron Structure of Nitrogen Peroxide” or “The Thermodynamics of the Nitrogen Oxygen Combination” would find shelter within the covers. Yet here they are in considerable numbers, and doubtless many of them will be of great interest to the physical chemists. With this preliminary observation it may pow be said that the book contains important metallurgical contributions. The text is suitably illustrated with photographic reproductions and diagrams, and each article is followed by such discussion aa it provoked a t the meeting. The papers are grouped into ten classes, the first five of which-covering 150 pages-contain most of the metallurgical matter. The remainder deal with spectra and molecular structure; general physical chemistry; surface chemistry, kinetics and photo effects; electrolytes; and finally electrochemistry. In these latter claases a few papers dealing with corrosion and electrodeposition are to be noted. A short account of the chromiumplating of light alloys by A. Koenig produced a considerable discussion but as a protection against corrosion this treatment is probably not as satisfactory as the well known anodic oxidising proceas dealt with in a paper by H. Rohrig. The large-scale production in recent years of aluminium of 99.95 per cent purity prompted M. Centnersawer to investigate its behaviour towards various acids and alkalies a t different temperaturea and concentrations. The results here recorded shew that the very pure metal is much more resistant to solution than that of “commercial” purity, especially in the case of N/z HCI. I n the metallurgical section proper, a certain amount of the work deals with such solidsolutions aa those of Au-Cu which precipitate intermetallic compounds on slow cooling. Thus Masing introduces them into his paper on the precipitation-hardening of alloys; Vogt into a study of magnetic susceptibility measurements of metals and alloys; whilst Eisenhut and Kaupp report upon their examination by the electron-diffraction procedure. This new method has yielded results which in some respects compare favourably with X-ray diffraction tests. Lattice distortion in alloys like duralumin which undergo age-hardening, is dealt with by Hengstenberg and Mark, X-ray intensity measurements being made at various times after quenching to obtain particulars of the reflection behaviour of the lattice. Recrystallisation phenomena are treated by Beck and Polanyi, and by Tammann, whilst yon Hevesy and Seith’s account of diffusion in metals concludes that the process is unilateral and not mutual. With the continued development of light alloys, papers dealing with magnesium are to be expected. The purification of this metal by vacuum distillation is described by Kaufmann and Siedler, and a technological article on “Elektron” alloys is contributed by W. Schmidt. A detailed study of the physical properties and metallography of magnesium is provided by E. Schmid, particulars being given of its binary alloys with Al, Zn, and Mn, together with the deformation of single crystals of the metal. New work upon this latter subject is not so much in evidence just now as it was a few years ago, but Coens and Scbmid contribute a paper on “Elasticity investigations of iron crystals.” Nothing is devoted specially to beryllium, but Masing introduces the Be-Cu alloys into his article on age-

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hardening, showing that after 8 1 hours the Brinell hardness number of one of them will I I Oto 360. These references to some of the papers will serve as an indication of the subjects represented in this publication. The tight metals and alloys have brought with them many new problems-as is made evident here by an excellent survey by G . Sachs-but the study of these problems has already produced a rich yield of useful results. Hugh 0’Neill.

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Recent Advances in Physical Chemistry. By Samuel Glasstone. 14 X 28 n;p p . viii 470. Londrm and New York: J . & A . Churchill i n P . Blakeston’s Son & Co., 1931. Price: 16 shillings. This text-book will be appreciated by teachers of physical chemistry at the Universities, for it covers a much wider range of subjects than can be dealt with adequately in university lecture courses to undergraduates. It can be used with advantage to supplement the information given in such courses. Among the topics discussed are the electronic theory of valency, dipole moments, molecular spectra, homogeneous and heterogeneous reactions, photochemical reactions, solubility, and strong electrolytes, and a very useful list of references is given a t the end of each chapter. The author has made a wide survey of the literature, and there is little that has escaped his net. There are, however, two topics missing that might have been dealt with in a work of this kind, viz. the solid state, and recent advances in thermodynamics. The mode of treatment on the whole is qualitative and there is no great depth of penetration. Equations are given, but no attempt is made to give an explanation of their physical basis. For example, the theory underlying the activation of gaseous molecules by collision is not given in the chapter on homogeneous gas reactions, although this theory is Rssential if students are to gain a proper grasp of what is actually happening in gaseous reactions. The book is also open to the serious criticism, that the author has devoted too much space to subjects already dealt with in monographs published in English. It is very largely, although not entirely, a text book compiled from monographs. There is too much space devoted to the approximate and elementmy theories of valency and too little attention paid to ideas based on the newer advances of physics. In spite of these faults, which seriously affect its value as a text-book for advanced students, it will prove a valuable addition to the libraries of teachers of chemistry in schools and to those chemists who wish to be informed of the present trend of chemical research. The hnok is interesting to read, and is well illustrated by suitable diagrams.

W . E . Garner. The Colorimetric and Potentiometric Determination of pH. Electrometric Titrations. 167. New York: John Wiley and Sac, 1951. By I . M . Kolthoff. 23 X 15 em; p p . xi Price: $2.26. This book is a condensed outline of the material contained in the author’s other publications on Potentiometric Titrations and Konduktometrische Titrationen. It is intended as a text for a special advanced course in analytical chemistry to familiarize the student with these important methods and to enable him to apply them to his own special problems of research. The book includes chapters on ( I ) Acids and bases, the reaction of aqueous solutions; ( 2 ) Indicators; (3) The colorimetric measurement of pH; (4) Electrode potentials; ( 5 ) The technique of potentiometric measurements; ( 6 ) The potentiometric measurement of the hydrogen ion activity; (7) Potentiometric titrations; (8) Conductometric titrations; and (9) An outline for a practical laboratory course of instruction. The theory involved is given very briefly and there is the possible criticism that many of the points such as salt effect, protein effect, indicator theory and the conversion of hydrogen ion concentration to pH, are inadequately covered. However the author gives references to the places where a more comprehensive treatment of most of these points may be found. Problems are introduced at the end of the chapters to illustrate the fundamentals discussed. The book was written “with the idea of offering an introduction to the above fields without claiming in any way an exhaustive treatment,” and the study of the theory given and the completion of the laboratory course should serve admirably to give the student an M . L. Nichols. adequate knowledge of these methods.

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