new books - ACS Publications

---

NEW BOOKS A Dictionary of Applied Chemistry. B y Sir Edward Thorpe. Vol. 111, Revised edition. 22 X 16 cm: p p . Viii 735. New York and London: Longmans, Green and Co., 1922. Price: $20 .OO per vo1.-The third volume includes such topics as: explosives; extraction apparatus; feeding stuffs; feldspars ; fermentation; fertilizers; filtration; fire extinction; flame; flash lights; flint; fluorine; formaldehyde; fritts; fuels; furnaces; fusel oil; gadolinium; gallium; gas; gems; glass; glucinum; glucosides; glue; glycerin; gold; granite; graphite; guanidine; gums; gutta percha; hardened oils; helium; hydrazine; hydrogen; hydrogen peroxide; hydrolysis; indanthrene; indigo; iodine; iridium; iron; kermes; ketones; krypton. On p. 5 it is stated that “an electrical charge causes sulphur to ball together and interferes with the grinding.” This seems very improbable. Electrification should act in the opposite way. The statement here made is not confirmed by ‘American practice. On p. 64 is the statement t h a t collodion cotton, or soluble nitrocotton, “is looked upon at the present time as a mixture, in varying proportions, of the di-, tri-, tetra-, and penta-nitrocelluloses of Eder’s classification.” This is a true statement; but it is a sad commentary on our scientific methods that after all these years we do not know how many nitrocelluloses there are and have no means of determining the constituents of any nitrocotton. Under explosives, p. 83, is an interesting paragraph on the theory of detonators. “The property of detonating another explosive does not depend merely on the violence of a n explosive, for Abel found t h a t 0.32 gram of mercury fulminate would detonate guncotton, whereas ten times the weight of the more violent nitrogen chloride was required. To explain the value of a n explosive in initiating detonation in other explosives, Abel advanced his theory of wave synchronism or sympathetic vibration. Wohler and Matter in the case of mercury fulminate, attributed its value as a detonant to the pressure produced by the kinetic energy of the molecules, t h a t is, t h a t it is due primarily to the rate of detonation and density of the fulminate, and secondarily t o the gas volume and heat, evolved. Nobel attributed this property of fulminate t o the very intense shock or pressure instantaneously set up on its explosion, and Berthelot, as mentioned when considering the properties of mercury fulminate, adopted the same view, but also called attention to the contributing fact t h a t the products of explosion undergo little, if any, dissociation. I t is certain that velocity of detonation and power, or total energy, alone do not determine the value of a n explosive as a detonant, otherwise nitroglycerin and blasting gelatin would have greater, instead of far less, detonating value than mercury fulminate, and mercury fulminate would have greater value than its admixtures with an oxidizing salt. It is probable that all these factors are contributory to the property of initiating detonation, and considering the high value of this property of silver, mercury, and lead compounds, fulminates, azides, picrates, and acetylides, it still seems that Abel’s original theory, or something analogous to it, is not entirely to be neglected.”

+

.

86

New Books

On p. 119 we read t h a t “bodies of the cellulose type, which resist the sol. vent treatments referred to, are to a variable extent partially digestible, especially by ruminants. This digestion is probably mainly effected by the action of bacteria in the large intestine. A ruminant can digest much more cellulose than a horse, and a horse much more than a pig. The very thorough mastication of the ruminant prepares the fibre better for such digestion as is possible than does the imperfect mastication of the horse or the still more imperfect mastication of the pig, apart from the anatomical differences in the digestive tracts of the respective animals and the relative abundance of bacteria capable of effecting cellulose digestion.” On p. 153 there is a statement in regard to the chemical changes involved in alcoholic fermentation. “Many theories have been advanced as to the stages which may he supposed to intervene between glucose and the final products of its decomposition-alcohol and carbon dioxide. Baeyer, in 1870, pointed out that the alternate removal and readdition of the elements of water might lead t o an accumulation of oxygen on certain of the carbon atoms, and thus render the rupture of the carbon chain possible. Wohl has proposed a modification of this idea, which leads to the supposition that loss of water and intramolecular change result in the formation of a ketoaldehyde which undergoes hydrolysis to methylglyoxal and glyceraldehyde; the latter of which by a similar series of changes, also forms methylglyoxal CHCOCHO. This then passes into lactic acid, and this into carbon dioxide and alcohol. This theory received a certain amount of experimental support from the fact that small quantities of lactic acid appear to be fermented by yeast juice (Buchner and Meisenheimer). The idea of the occurrence of lactic acid as a true intermediate product of alcoholic fermentation has, however, now been abandoned, largely owing t o the criticisms of Slator, who pointed out that this substance should be fermented a t least as quickly as glucose, and that this is not the case. The same criticism is valid against many of the 3-carbon compounds which have been proposed as intermediate products, including glyceraldehyde and dihydroxyacetone, both of which are slowly attacked by yeast, while dihydroxyacetone is also readily fermented by yeast juice prepared by maceration (Lebedev). “The universal presence of carboxylase in yeasts capable of producing alcoholic fermentation creates a strong presumption that the decomposition of pyruvic acid actually forms a stage in the alcoholic fermentation of sugars. The fact that the evolution of carbon dioxide from pyruvic acid commences instantly, whereas there is a considerable delay in the case of glucose is interpreted to mean that the glucose undergoes a preliminary change which requires some time and results in the formation of pyruvic acid capable of immediate decomposition. Other explanations of this delay, which is by no means invariable, can, however, be given. A number of observations have also been made by Euler and his school which have led him t o the same conclusion, that some intermediate product is formed before the production of alcohol and carbon dioxide.” Under fire extinction there is no mention of Foamite and the article on flames might have been written fifteen years ago. On the other hand, Argo’s work on fluorine is cited. In view of the importance of fluor-spar for apochromatic lenses, p. 234, one wonders why suitable material could not be made synthetically. As an instance of adsorption we may cite the removal of fusel oil from spirit,

.

New Books

87

p. 291. “The most approved method of separation, however, is by well-burnt granulated vegetable charcoal or bone-black. The charcoal is placed upon perforated trays in a vessel surrounded by a cooling jacket, and the spirit, usually diluted to about 160” Tr., is caused to pass through several layers. The operation should not be performed above the ordinary temperature, as the fusel oil is again dissolved from the charcoal near the boiling temperature. From 3 to 5 vols. of charcoal are required for the successful treatment of 100 vols. of brandy. The whole of the fusel oil is evolved from the charcoal on treatment by superheated steam, and the charcoal may be repeatedly used after heating to redness to drive off the occluded gases, etc. It is noticeable that the fusel oil obtained by steaming the charcoal does not represent the whole of that removed from the spirit, nor are sufficient compounds which might be produced by the decomposition of the fusel oils found t o account for this loss.” I t is rather staggering to read, p. 374, that the principal flavoring ingredients used for gin besides juniper are “angelica root, almond cake, calamus root, cardamon seeds, cassia buds, coriander seeds, creosote, liquorice powder, orris root, sweet fennel, and turpentine. . . . . .Plymouth gin is a special variety of gin made in Plymouth, and used extensively in the West of England. It has a characteristic flavor, said to be due t o ether resulting from the addition of a little sulphuric acid to the spirit to be rectified.” After this it is comforting to learn that the adulteration of gin, except by dilution with water is not common, though alum and salts of lead and zinc have sometimes been found. On p. 402 we read that “the frequent association of phosphatic nodules with glauconite deposits has some bearing on the origin of glauconite. The terrigenous deposits of green mud and sand formed on the floor of the ocean a t depths of about 200 t o 1000 fathoms, and found by the Challenger Expedition to be of wide distribution, particularly off continental coast lines composed of igneous rocks, contain this mineral in considerable amount. The potash set free by the weathering of the feldspars and micas of these rocks and carried into the sea is conserved by the formation of glauconite, but apparently only through organic agencies, which a t the same time gave origin to the phosphatic nodules. Grains of glauconite are frequently found filling the chambers of foraminifera and other organisms; and in the artificial production of the mineral the presence Wilder D. Bancroft of a n organic acid seems t o be essential.”

The Chemistry and Technology of Gelatin and Glue. By R. H . Bogue. 23 X 16cw;pp. xi f 6gg. New York: McGraw-Hill Book Company, 1922. Price: $b.oo.-There is an introductorychapter on historical and statistical considerations, after which come five chapters on the theoretical aspects, entitled respectively : the constitution of the proteins; the chemistry of gelatin and its congeners; the physico-chemical properties and structure of gelatin; gelatin as a lyophilic colloid; gelatin as an amphoteric colloids. The second part of the book deals with the technological aspects, the sub-heads being: the manufacture of glue and gelatin (written by Ralph C. Shuey); water-resistant glue and glues of marine origin; the testing of glue and gelatin; the chemical analysis, detection, and estimation of gelatin and glue; the evaluation of glue and gelatin; the uses and applications of glue; the uses and applications of gelatin. It will perhaps be well to discuss some of the weak points of the book

88

New Books

first and then we can take up the really interesting things. Perrin worked with gamboge and not with gutta percha, p. 105. Under foamite, p. 554, the aluminum sulphate has been forgotten. So far as the reviewer is concerned, a semipermeable membrane is not a n ultra-filter, p. 141. The fact t h a t the swelling of gelatine in water is accompanied by a n evolution of heat, p. 164, is scarcely a conclusive proof of the existence of solvates, p. 193. On p. 223 we read that acids combine with deaminized gelatine t o nearly the same degree as with untreated gelatine. The author draws the conclusion that “as there can be no terminal amino groups in the deaminized product, it is obvious that the acid reacts with some internal groups.” This conclusion is necessary and obvious only in case one insists on postulating a definite compound. The reviewer noted with pleasure the fact that the adsorption of gelatine by glass is made use of technically, p. 538. “E’rosted glass is a form of glass t h a t is much used in the doors and partitioning windows of offices where privacy is desired. It is made by allowing a glue or gelatin to dry out rapidly upon a plate of ordinary rather thick glass. As the glue loses its moisture it contracts, and the power of the gelatin is so great it tears away the surface of the glass itself, chipping it into characteristic fern-like patterns. The general appearance of the design can be modified by varying the properties of the glue used; i. e., a brittle glue will give a different pattern from a tough glue, and the addition of salts also modifies the patterns. A strong gelatin solution containing six percent of alum gives exceptionally fine designs.” The following passages interested the reviewer, pp. 49, 90, 355, 288, 466, 499, 491, 518. “In plant physiology the principal structural material producing turgor and rigidity is cellulose, a highly polymerized carbohydrate. In the animal a protein, often fortified by inorganic salts, serves in this capacity. Among the invertebrates the hard shell-like coverings are composed largely of a protein called chitin. I n the vertebrates the protein material of the bones and of the several connective tissues is a mixture of several proteins, the most important of which is collagen. The organic material of the bones, the tendons, the cartilage and the skin, is to a great extent comprised of collagen. When this collagen is obtained from different tissues it is round t o vary slightly in its composition and this has led some writers to regard it not as a definite chemical compound, but rather as a mixture the composition of which is variable within certain limits. When collagen is heated in water to 80 or 90 C , it is converted slowly into the protein gelatin. This conversion would be greatly accelerated if the temperature of the water were raised to or above the boiling point (under pressure) or by the use of dilute acids, but such a procedure would in turn, result in a further hydrolysis of the gelatin, as soon as it was produced, and so greatly lessen the yield and quality of the product.” “The sounds, or air bladders, or swimming bladders, as they are variously called, consist almost entirely of collagen, and have the additional advantage of being exceptionally free from other impurities which might be dissolved out upon heating with water. They also differ from other varieties of collagen in being more readily soluble in warm water than any other type. On account of this unusual purity and the consequent very high quality of the gelatin obtained from them, they have been used for a great many years in the preparation of what

New Books

89

is known as isinglass. Many varieties of fish have been used in the preparation of isinglass. The most notable of these is the sturgeon, it being the first fish to be used extensively for commercial isinglass, and its product is still the standard upon which all others are based. It is made up in several ways, which will be described later, and large amounts are still exported from Russia. Catfish and carp also contribute to the Russian product. Many other countries produce sounds, usually of somewhat inferior quality t o the Russian. Cod and ling sounds are obtained from Iceland, cod sounds from Norway, miscellaneous types from Venezuela, Brazil, Penang and Bombay. In America, especially in the Canadian waters, sounds are obtained mainly from the hake, cod, squeteague, and more recently the tilefish.” “One of the oldest and best established uses of isinglass is as a clarifying agent Tor various beverages, as wine, cider and malt liquors. The efficacy of the isinglass for this service lies in the purely mechanical property it possesses of maintaining a .fibrous structure in the solution, and as this settles slowly to the bottom i t entangles in its net-like meshes the colloidal bodies that produce the undesirable turbidity. For clarifying wine the isinglass is first swollen in water and then in the wine until it is completely swollen and transparent. It is then thoroughly beaten into a small amount of the wine, strained through a linen cloth, and stirred into the rest of the wine. The temperature is kept low and the isinglass does not go into solution, but only into a very finely divided suspension. Thus the original fibrous structure of the sounds has a t no time since it came from the fish been lost. In this lies the difference in the action of isinglass and gelatin for fining. If isinglass were heated and made into a true gelatin it would then have lost the properties which make it so valuable for this service. A single ounce of isinglass will clarify, under the optimum conditions, 500 gallons of wine i n 10 days. In the manufacture of beer and ale the starch granules, bacteria, and protein matter, which do not settle in the tanks after the primary fermentation are gotten out by either filtration, adsorption upon wood chips, or fining. I n the latter procedure the isinglass is treated with sour beer and, after swelling, macerated as in the fining of wine. After straining it is mixed thoroughly with the rest of the beer. One pound of isinglass will fine from 100 to 500 barrels of beer.” “The mucinous impurities carry nearly the same electrical charge on their colloid particles that gelatin particles carry. On this account the protectiye action of the gelatin narrows very greatly the limits within which good filtration can be accomplished. The substances to be filtered out appear all to be negative, and the use of fuller’s earth which is strongly negative does not improve appreciably the appearance of the glue. On the other hand, if alumina, a strongly positive substance, is used, the liquor will run clear but the filter will block almost immediately. Charcoal is almost neutral and will produce successful filtration for a considerable time. However, the filtering substance preeminent for this purpose is cellulose. Being very slightly negative it holds the particles without holding the glue, and although the actual surface per unit volume is probably much less than with charcoal, the filters are so constituted that they will hold a maximum amount of precipitate before blocking. A convenient form of cellulose is a good grade of cotton paper pulp. Many different forms of filters for holding such pulp are obtainable, but those allowing for a loose packing of the pulp on the

I

.

90

.

.

New Books

intake surface will provide a matte of considerably longer life than if the filter matte is required to be densely packed throughout. “Although certain liquors can be filtered perfectly bright, many of them will cloud on cooling and practically all of them cloud on concentrating. To remove this precipitated or precipitable material and thus obtain a brilliant gelatin it is necessary either to produce a colloidal coagulation or to cause the formation of a precipitate or aggregate which will collect and hold by forces allied to adsorption the objectionable substances.” “A study of the gelatin-tannin reaction was made by Trunkel in 1910. He found that 1 gram of gelatin required 0.7 gram of tannin lor complete precipitation when used in a freshly prepared condition, but after the gelatin solution had stood for 24 hours only 0.4 gram of tannin was required. If the latter solution is warmed, however, it regains its former power to precipitate tannin, Where the gelatin and the tannin are both precipitated quantitatively, the precipitate resists decomposition by water, but with an excess of tannin a precipitate may be obtained, containing 3 tannin to 1 gelatin which, however, yields up tannin on treatment with water. By repeated extraction of the precipitate with alcohol, up to 96 percent of the tannin may be removed, but in no case can the precipitate be entirely resolved into its constituents. Only about 6 percent of unaltered gelatinizable gelatin may be extracted from the residue. T h e action of alcohol leads Trunkel to believe that the precipitation of gelatin by tannin is an adsorption process.” “Our discussion has shown, therefore, that both the gelatin content of a glue or gelatin, and also the joint strength of a glue, m?y be correctly indicated by a melting point determination, while neither may be correctly assumed to be, in all cases, proportional to either the jelly consistency or the viscosity a t 60’ C alone. Inasmuch as the primary evaluation of the material should be based upon some fundamental and scientifically selected property or properties, it seems that gelatin content and joint strength should be chosen. I t is especially happy that these two properties are parallel. Since the melting point has been shown to indicate the gelatin content and the joint strength, it seems t h a t this determiiiation, either directly or indirectly made, should be selected as a measure of the fundamental constitution and properties of the material. The measurement of the viscosity of an 18 percent solution, dry basis, a t 35’ C, by means ol the MacMichael viscosimeter has been shown to be especially well adapted as a n indirect estimation of the differentiation of glues and gelatins in the order of their melting points, and is accordingly recommended as the basis for the primary evaluation of these products.” “The secondary basis for glue or gelatin evaluation lies in many or few othkr tests which are employed to determine the application of the material for any special service. For example, where the glue is to be used in mechanical spreaders, the tendency to foam is undesirable, and the foam test indicates this tendency. If the glue be applied by hand, the foam test is of little or no significance. If the glue is for use on paper as a size or wall paper as a binder for the clay filler, grease should not be present in large amount, as otherwise little droplets of this substance form, making elliptical ‘eyes’ or spots on the paper. I n admixture with certain dyes the presence of acid or of alkali is not permissible a s the dye would be affected in one way or another. Suitable tests must accordiiigly

New Books

91

be made upon glues designed for such purposes. Gelatin for use in photographic films or in printing rollers must have high jelly strength; if used for food or medicinal purposes it must be free from harmful impurities; if used in making marshmallows or other emulsions, a high viscosity and foam are desirable. Such a list could be extended greatly, and the adaptability of any glue or gelatin for its several uses is determined largely by such secondary tests.” “Among the factors which have been found to influence the strength obtainable in a glued joint, made with any given glue, are the following: the concentration of the glue solution; the time occupied and temperature employed in heating the glue; the temperature of the glue when applied; the species, density, porosity, and moisture content of the wood used; the trueness of the joint; the amount and method of application of the glue in the joint; the temperature of the wood when glue is applied; the rapidity of handling; the pressure applied t o the joint, and its uniformity of distribution; the time under pressure, and time of curing; the temperature and humidity during curing; the method of breaking the joint; the hydrogen-ion concentration of the solution.” People have claimed that too much pressure must not be used in gluing surfaced wood, as the glue may be pressed out too completely from the joint, producing a so-called starved joint; but the author concludes, p. 524, that “as the layer of glue between the wood pieces is made vanishingly small, the strength of the joint will approach its maximum value. The bond between the two pieces of wood should consist only of the vertical and interlaced threads of glue passing from the pores in one piece to the pores in the other. If this is the case, and we seem justified in making that conclusion, then it must follow that, provided the glue is properly applied, and in a condition such that a fair degree of penetration results, there can be no such an effect as a ‘starving’ of a joint, and no such thing a s too much pressure, as far as the glue is concerned. The advantageous results realized by high pressures can be explained only upon the assumption that such pressures are necessary to squeeze out the maximum amount of excess glue in the joint, and to minimize any slight inequalities in the perfection of the joint.” Wilder D . Bancroft Catalysis in Organic Chemistry. By Paul Sabatier. Translatsd by E . Emmet Reid. 23 X 16 cm; p p . xxiv 406. New York: D . Van Nostrand Company, 1922. Price: $.~.oo.---The German translation of the first French edition was reviewed eight years ago (19, 78). We now have what purports to

+

’

be the English translation of the second French edition; but which is really a good deal more than that, because Professor Reid has added a number of valuable footnotes which bring the book more up-to-date. These additions are the more valuable because they refer in great part t o work done in this country. The headings of the chapters are: catalysis in general; on catalysts; mechanism of catalysis ; isomerization, polymerization; depolymerization, and condensations by addition; oxidations; various substitutions in molecules; hydration; hydrogenation (5) ; various eliminations; dehydrogenation; dehydration (3) ; decomposition of acids; decomposition of the esters of organic acids; elimination of halogen acids or similar molecules; decomposition and condensation of hydrocarbons; hydrogenation of liquid fats. The book is a store-house of facts and problems. In the following para-

,

.

92

New Books

graph, p. 114, one would like to know whether there is any relation between the amounts of iodine converted into hydriodic acid and to nickel iodide. “In an apparatus in which the hydrogenation of benzene was progressing regularly over nickel a t BO”, the benzene was replaced by benzene containing 0.5% iodine. The hydrogenation continued for several hours with an excellent yield. The escaping hydrogen, after the condensation of the cyclohexane, disengaged abundant fumes of hydriodic acid showing that the iodine had been hydrogenated by the catalyst. The operation was interrupted after 130 g of cyclohexane had been collected and it was found that the nickel had combined with iodine in the first half only of the tube. This half was incapable of carrying on the hydrogenation but the other half was unhurt. The poisoning of the metal by the iodine had taken place only slowly and step by step; the hydriodic acid had had on its own account, no harmful effect and had not converted into the iodide the metal the surface of which was covered with an unstable hydride which produced the hydrogenation. Doubtless the fixation of the hydrogen on the iodine and the benzene in contact with the nickel is much more rapid than the reaction of the nickel with the iodine or with the hydriodic acid. As in the direct hydrogenation of unsaturated hydrocarbons, the metal protects itself, by its own action, against the permanent alteration which would render it inactive.” On p. 126 there is an interesting paragraph on regeneration. “Metallic catalysts poisoned by vapor8 of chlorine, bromine, iodine, sulphur, etc., are difficult to revivify except by dissolving in a suitable acid and working over completely. Calcination does not remove chlorine from slightly chlorinated nickel. The action of hydrogen reduces the chloride to the metallic state below 400°, but the resulting metal is in a peculiar fibrous state and is incapable of reducing benzene t o cyclohexane. Even after oxidation and a second reduction it is a poor catalyst. It can be restored slowly to complete activity by employing it for some time in the reduction of nitrobenzene to aniline, work which poisoned nickel is still capable of doing. The aniline which is produced contains increasing amounts of cyclohexylamine. After some hours of this treatment the power of the metal t o produce cyclohexane from benzene is restored completely. On the other hand, poisoning by bromine or iodine seems to resist this treatment.” On p. 341 we read t h a t in the action of alcohols on esters, “sodium alcoholate is an even better catalyst than hydrochloric acid. I n the transformation of methyl benzoate into the ethyl ester, sodium ethylate was found t o be about four thousand times as efficient as an equivalent amount of hydrochloric. acid.” I t does not appear, p. 596, why vigorous stirring should beessentialto hydrogenation. “Very extensive use has been made of the common metals, particularly nickel, for hydrogenation in liquid medium in the case of liquid fats the molecules of which contain ethylene bonds. The description of the methods followed and the results obtained is the special object of the last chapter but the same process can be generalized and extended to a large number of cases. The fundamental condition of success is a sufficiently energetic agitation in the hydrogen. A pressure of several atmospheres is useful but not indispensable, t h e hydrogenation being capable of being carried out even with reduced pressure. Simply bubbling the hydrogen through the liquid is not sufficient.”

I

.

93

New Books

Sabatier distinguishes three reactions with esters, p. 861 : CHsCOzCzH5 = CHsCOzH f CZH4, COz CzH4 f CzH,OH, 2 C H ~ C O ~ C Z=HCHsCOCHs ~ CH3COCHa f COz f 2C2Ha f HzO. 2 CHsCOzC2HS The reviewer has followed Sabatier's lead in this respect in the past; but he now thinks that it would be more profitable to consider these as different stages of the same reaction. The first stage would then be in all cases the formation of acid : CHaCOzCzHs = CHsCOzH CzHd The next stage would be CHaCOzH CH3C02CAHs CzHd = CH3COCH3 COz f CzH5OH CzHd, and the final stage would be CHlCOzH CH3C02CaH5 CzH4 = CHXOCH, COz 2CzH4 f H2O. The action of nickel on acetylene a t 180" is apparently a triple one, p.

+

+ +

+ + +

+

+ +

+

+

918. 1. Rapid decomposition into carbon and hydrogen with polymerization t o aromatic hydrocarbons. 2. Slow condensation into a solid hydrocarbon doubtless identical with cuprene. 3. Hydrogenation of the acetylene and of the aromatic hydrocarbons with production of aliphatic, unsaturated and cyclo-aliphatic hydrocarbons. All readers will be grateful to the translator for supplying forty-two pages Wilder D. Bancroft of subject index.

The Properties of Electrically Conducting Systems. B y C. A . Kraus. The Chemical Catalog Company, 1922. Price: $d..;o.-"The purpose of the present volume is to present the more important of this material [relating to our conceptions of matter in the ionic condition] in a comprehensive and systematic manner, thus enabling the reader to gain a knowledge of the contemporary state of this subject without an undue expenditure of time and effort." The 'subject is presented under the following headings: introduction; elementary theory of the conduction process in electrolytes; the conductance of electrolytic solutions in various solvents; form of the conductance function; the conductance of solutions as a function of their viscosities; the conductance of electrolytic solutions as a function of temperature; the conductance of electrolytes in mixed solvents; nature of the carriers in electrolytic solutions; homogeneous ionic equilibria; heterogeneous equilibria in which electrolytes are involved; other properties of electrolytic solutions; theories relating to electrolytic solutions; pure substances, fused salts, and solid electrolytes; systems intermediate between metallic and electrolytic conductors; the properties of metallic substances. On p. 65 the author points out that "it will be observed that the ion conductance in ammonia and in water do not stand in a fixed ratio. For example, for the silver ion, the ion condiictance in ammonia is 2.15 times that in water, whereas for the lithium ion the conductance in ammonia is 3.36 times that in water. Similiarly, the conductance of the bromide ion in ammonia is 2.54 times t h a t in water, while the conductance of the bromate ion is 3.11 times that in 23

x 16 cm; p p . 4 1 5 , New York:

New Books water. We may naturally inquirc as to what are the factors upon which depends the conductance of different ions in different solvents. “If the current is carried through a solution by the translation of charged particles of molecular dimensions, then we should expect the speed of these particles to be a function of the viscosity of the medium through which they move. I t might be assumed, for example, that the conductance is proportional to the reciprocal of the viscosity, or to the fluidity of the solvent. This viscosity of water and that of ammonia is 2.558 X 10-3 a t its boiling point. a t 18’ is 10.63 X Consequently the fluidity of ammonia is 4.15 times as great as that of water. If the conductance of the ions were directly proportional to the fluidity of the solvent, then the conductance of all ions in ammonia should be 4.15 times as great as t h a t of the same ions in water. We see, however, that while the conductance of the various ions in ammonia is markedly greater than that in water, nevertheless the ratio of the ion conductance in the two solvents is in all cases smaller than this value. Furthermore, the etfect is one specific with respect to the individual ions. For example, for the sodium ion, the value is 3.0, while for the lithium ion i t is 3.36. It is noticeable t h a t the ratio for the ions increases in the order: ammonium, potassium, sodium, lithium. In other words, in ammonia the lithium ion possesses a relatively much higher conductance with respect to water than does the ammonium ion. . . “It is evident t h a t the conductance of a n ion is a function of the constitution of the solvent as well as of t h a t of the ion itself. In this connection it should be observed t h a t a given electrolyte dissolved in two different solvents does not necessarily yield the same ions. I n other words, complexes may be formed between the ions and the solvent properties of which will depend upon the nature of the solvent. It is well known t h a t certain ions tend to form complexes with certain solvents. For example, the silver ion forms a complex with ammonia even in aqueous solutions. I t may be assumed, therefore, that the silver ion has a great tendency to form complexes with ammonia.. The cause for the relatively low value of the conductance of the silver ion in ammonia may be ascribed t o the formation of a relatively large complex silver-ammonia ion in ammonia solution. Similarly, those ions whose salts show a marked tendency t o form complexes with water, which, for example, give stable crystalline hydrates, show a relatively higher speed in ammonia than in water. Thus, the speed of the lithium ion in ammonia is relatively much greater with respect to its speed in water than is t h a t of the potassium ion. We may therefore conclude that the lithium ion is relatively less complex in ammonia than it is in water.” At higher temperatures the values of all transference numbers tend to approach one half, p. 124. “These results have a n important bearing on our conceptions as t o the nature of the conducting particles, particularly as regards the effect of temperature on the speed of these particles. As has been shown by means of transference experiments, the ions are hydrated in water. In order t o account for the fact that the speeds of the different ions at higher temperatures approach one another, it might be assumed that the hydrates break down a t higher temperatures, but this assumption would not be in harmony with certain facts. Since the conductance of the slowly moving ions changes in direct proportion to the fluidity of the solvent as the temperature increases, it is reasonable to assume that the relative dimensions of the ion complex remain practically

.

New Books

95

constant. If, therefore, the speed of the more rapidly moving ions approaches that of the more slowly moving ions a t higher temperatures, it points t o a slowing up of the more rapidly moving ions as the temperature increases. This corresponds t o a greater relative resistance t o their motion, which can only be interpreted as due to a n increase in the dimensions of the ion-complex. In other words, as the temperature increases, the hydration of the more rapidly moving ions increases, which tends t o reduce their speed relative to that of more slowly moving ions. “If the hydration of the ions is due primarily to electrical forces acting between the ions, which are charged, and the surrounding solvent molecules, which have a n electrical moment, then we should expect that, as the dielectric constant of the medium decreases, the size of the complex will increase since in a dielectric medium the force is inversely proportional to the dielectric constant. For this reason we should expect the relative speeds of ions in non-aqueous solvents of low dielectric constant to approach one another much more nearly than they do in water. This appears t o be the case. Moreover, this is also in harmony with the fact that in the case of very large ions, in other words, in the case of ions which have a low conducting power, the conductance in different solvents, as well as different temperatures, is very nearly proportional to the fluidity of the solvent. We may conclude, therefore, that the hydration of the ions increases, or, including nonaqueous solvents, that the solvation of the ions increases with the temperature because of a decrease in the dielectric constant of the medium. It is not to be assumed, holyever, t h a t the dimensions of the ions in different solvents are controlled entirely by the dielectric constant. The solvent may combine chemically with a given ion t o form a complex, which ion in turn may have associated with it additional solvent molecules, due t o electrical interaction between this ion and the solvent. We should expect this t o be the case with silver ions which form a n extremely stable complex with ammonia. Even in aqueous solutions, the silver ion forms a complex Ag(NH&+ with ammonia. This may account for the relatively low conducting power of the silver ion in liquid ammonia solution. Whereas, for example, the conductance of the lithium ion in ammonia is 3.36 times that of the lithium ion in water, that of the silver ion in ammonia is only 2.15 times t h a t in water. So, also, we find that the ammonium ion in ammonia has a conductance of only 2.03 times that of the ammonium ion in water, indicating the formation of relatively large complexes. In this connection it may be pointed out that the ammonium salts form with ammonia saturated solutions whose vapor pressures are extremely low. For example, the vapor pressure of a saturated solution of ammonium nitrate in ammonia is one atmosphere at 26O.” The question of conductance near the critical point is an important one, p. 167. “Data relative to the ionization of solutions in the critical region are entirely lacking, for which reason it is not possible to interpret the results of conductance measurements with any degree of certainty. However, the conductance data indicate that the properties of solutions in the critical region do not differ materially from those of solutions a t lower temperatures. WIoreover, it appears that the property of forming electrolytic solutions is by no means confined to the liquid state of matter. Fluids above the critical point yield electrolytic solutions and even the solvent vapors themselves, below the

9G

New Books

critical point, possess the power of dissolving electrolytes, forming solutions which conduct the current. . “ I t has already been pointed out that, as the critical point is approached, the conductance of solutions in solvents of low dielectric constant approaches a very low value, and the conductance-temperature curve if extrapolated would intersect the temperature axis a t a temperature not far removed from the critical temperature. It is known, however, that, once the critical point has been reached, the conductance falls only very slowly with increasing temperature. I n other words, the conductance-temperature curves exhibit a discontinuity in the immediate neighborhood of the critical point. As will be seen below, this behavior is what we should expect when conductance measurements are carried out in sealed tubes, where the total volume of liquid and vapor remains constant. In the immediate neighborhood of the critical point, the density of the solvent decreases very rapidly with increasing temperature, whereas beyond the critical region the density of the solvent medium remains fixed. The rapid decrease in conductance immediately below the critical point is to be ascribed to the rapid decrease in the density of the solvent medium. “It is t o be expected that the ionization and consequently the conductance of solutions in the critical region will be governed largely by the dielectric constant of the medium, and it may be inferred that those liquids, which under ordinary conditions exhibit a very high dielectric constant, will likewise exhibit a relatively high dielectric constant in the critical region. In the case of sulphur dioxide and ammonia the dielectric constant in the critical region is very low, whereas in the case of the lower alcohols and water a relatively larger value of this constant is to be expected. Water would be a n ideal substance for the purpose of studying the properties of electrolytic solutions in the critical region, were it not for the difficulties attending conductance measurements in this solvent a t high temperatures. These difficulties, however, disappear very largely in the case of the lower alcohols, although it is to be expected that the ionization in the critical region will be markedly lower in these solvents than in water. . . . “According t o the commonly accepted theory of electrolytic solutions, the change in the conductance of solutions as a function of the concentration is due to a change in the relative number of carriers; that is to a change in the ionization of the electrolyte. Because of various difficulties which have arisen in accounting for the properties of strong electrolytes, some writers have suggested that strong electrolytes in solution are completely ionized. The study of the properties of non-aqueous solutions and of solutions at higher temperatures yields no apparent support for such a n hypothesis. If the salts in solvents of low dielectric constant are completely iohized, then it becomes exceedingly difficult to account, on the one hand, for the very low value of the conductance of these solutions a t certain intermediate and low concentrations and, on the other hand, for the very rapid increase in the conductance of these solutions a t higher concentrations. So, in the case of solutions in the neighborhood of the critical point, i t is difficult to account for the rapid decrease in the conductance of the solution as the critical point is approached on the basis of this hypothesis. Again, in the case of solutions above the critical point, the large increase in the conductance of the solution as the concentration of the solvent increases is with difficulty accounted for on the assumption that the electrolyte is completely ionized,

New Books

97

unless, a t the same time, an hypothesis is introduced according to which the speed of the ions through the solvent medium is enormously increased by a n increase in the concentration of the solvent. For such an hypothesis there is a n entire lack both of experimental facts and of theoretical support. “On the other hand, if the fundamental elements of the usual theory of electrolytes are accepted, we are forced t o the conclusion that the ionization of electrolytes is a complex function of the concentration and that, a t very high concentrations, in the case of solvents of low dielectric constant, the ionization increases with the concentration. While theoretical support is lacking for this assumption, no theoretical principles are contradicted by such an hypothesis. Furthermore, if we assume that the ionization of electrolytes is a funciion of the concentration and is approximately measured by the conductance ratio h / h o ,the influence of temperature, of concentration, and of the viscosity of the solvent may be readily accounted for without contradicting known facts and without introducing any further hypotheses for which a theoretical foundation is lacking. In other words, on the basis of the ionization hypothesis, it is necessary to make only a single assumption whose correctness remains uncertain, whereas in the case of other hypotheses a number of assumptions are necessary. Unless other and more conclusive facts can be adduced in support of the hypothesis t h a t the strong electrolytes are completely ionized in solution, this hypothesis is clearly untenable a t the present time.” There are some unexpected phenomena in mixed solvents, p. 181. “The effect of adding water to a solution of hydrochloric acid in methyl alcohol is t o decrease greatly the conductance of the solution and this effect is relatively independent of the concentration of the solute. It appears, therefore, t h a t the ionization of hydrochloric acid is not materially affected by the addition of water, but t h a t the speed of the hydrogen ion is reduced greatly. It is true that on the addition of water to methyl alcohol the viscosity is increased; but the viscosity change due to the small amounts of water added in the case of these solutions is inconsiderable and cannot account for the large decrease in the conductance of these solutions. Apparently, therefore, the change in conductance is due t o a slowing up of the hydrogen ion, since i t is known t h a t the chloride ion is normal in its behavior in mixtures of alochol and water. The values given for the limiting value of the equivalent conductance are approximate, since the extrapolation function employed in determining these values is uncertain.” The author believes, p. 206, t h a t “the hydrogen ion in water is, in fact, not a hydrogen ion, but a n oxonium ion. Whether the charge is associated with the hydrogen or with the oxygen atom cannot be determined in this case any more than i t can in t h a t of the similar ammonium salts. It appears likely, however, t h a t in salts of this type the charge is associated either with the oxygen or nitrogen atom, or with the group as a whole, rather than with one of the hydrogen atoms.” On p. 238 we read t h a t “Nernst has called attention to the fact that, since the law of mass-action in its simple form does not hold for solutions of strong electrolytes, the laws of dilute solutions cannot be applied t o these mixtures. As a consequence, if the ionization is determined correctly by the conductance method, the ionization as determined by osmotic methods, assuming the laws of dilute solutions t o hold, should differ from that determined by conductance meas-

98

New Books

urements. I t appears, however, that in the case of certain electrolytes, such as potassium chloride, osmotic methods and conductance methods lead to the same value of the ionization, and, in the case of other electrolytes, the two methods lead to very nearly the same value a t concentrations approaching 10-3 normal. Yet, in the neighborhood of normal, strong electrolytes do not conform to the simple law of mass-action. Those who would use the results of osmotic methods to substantiate the correctness of the results of conductance methods thus find themselves in a dilemma, for, if the two methods lead t o identical values of the ionization, then, if the results of osmotic measurements are looked upon as correct, the interpretation of conductance measurements must be in error, while, if the results of conductance measurements are accepted in their usual sense, the laws of dilute solutions are inapplicable. That the concordance of the ionization values determined by conductance and osmotic methods a t low concentrations if a n accidental one is very improbable. It appears, rather, that this agreement is the expression of a fundamental property of such solutions. The significance of this agreement, however, remains uncertain.” With solid electrolytes, we may have the transference number for either ion equal t o zero, p. 363. “It has been shown that for silver bromide, silver chloride, silver sulphide above its transition point, and copper sulphide (Cups),Faraday’s Law holds and that in these salts the current is carried entirely by the positive ion. These results are very significant in that they show that one set of ions in these solids forms a fixed framework through which the other ions move with considerable facility. In the above salts, the negative ions form the framework through which the positive ions move. In lead chloride, however, the current is carried by the negative ion; the positive ions form the framework through which the negative ions move. These facts have an important bearing on the theory of the structure of solid salts. “Silver sulphide has a transition point at 179”. Above the transition temperature, as was shown by actual electrolysis of the salt, Faraday’s Law holds and the current is carried entirely by the positive ions. Below the transition temperature, the p form of silver sulphide appears to conduct in part metallically. In the p form of silver sulphide, Faraday’s Law does not hold, only about 80 percent of the current being carried by the silver ion. The negative ion in this case is apparently not involved in the conduction process, the remainder of tlie current being carried by a metallic process of conduction. Apparently, therefore, solid electrolytes exist in which the current is carried partly metallically and partly electrolytically. As we shall see in a subsequent chapter, solutions of the alkali metals in liquid ammonia likewise conduct the current by a mixed process.” This is a very interesting book. The criticism might be made, especially with reference to the dilution law, that the author’s formula receives relatively too much attention. The reviewer would have liked to have seen Schlundt’s work on transference numbers referred to. These are details, however, and we are grateful to the author for giving us a clear-cut presentation of the subject. Since our knowledge turns out to be much less than some of us had hoped, the real question is what we are going to do about it. It is quite evident that the physical chemists should get together and try to map out a campaign which Wilder D . Bancroft will clear up these points.

.

New Books

99

Women in Chemistry; a Study of Professional Opportunities. Issued by the Bureau of Vocatzonal Information. 23 X 15 cm; p p : xvi 272. New York: Thr Bureau of Vocational Information, 19zz.-This bulletin aims to give the woman who studies chemistry some idea “of the various kinds of positions available in chemistry and the border fields, particularly bacteriology and physiology.” The bulk of the volume is devoted to a n analysis of positions in chemistry for women in: educational institutions; laboratories for medical and related analysis and research; laboratories for industrial analysis, development and research; government laboratories. There is a short chapter on training and another on further vocational considerations, while, in an appendix, there is given information in regard to: colleges and universities in which women may secure graduate training in chemistry; prizes and grants available for research in chemistry; fellowships and graduate scholarships open to women; scientific, technical, and other periodical publications of interest to chemists, scientific societies for chemists. The whole thing has been done in very good style and the bulletin will be Wilder D . Bancroft of value to women and of interest to others.

+

Laboratory Manual of Physical Chemistry. B y .4. W . Davison and 198. New York: John Wiley and H . S. van Klooster. 25 X 15,cm; pp. viii Sons, 1922. Price: $z.oo.-The laboratory course follows immediately the com-

+

pletion of the theoretical course in physical chemistry at the Rensselaer Polytechnic Institute. Each student is expected to do all the experiments. These include: determination of vapor density; Graham’s effusion law; surface tension and association factor of liquids; refractive index density, and molecular refractivity of liquids; lowering of the freezing point by a non-electrolyte and by an electrolyte; molecular weight determination by the boiling-point method; distribution of a substance between two non-miscible liquids; distillation with steam; minimum boiling liquids; boiling-point and vapor composition curves of liquid mixtures; solubility curve for a ternary system of liquids; transition points in the solid state; inversion of cane sugar; sodium thiosulphate reacting with ethyl bromacetate; heat of neutralization; heat of combustion; heat of solution; adsorption of dissolved substances by charcoal; conductivity and degree of ionization; transport numbers; hydrogen ion concentration and electrometric titration; electromotive force measurements and concentration cells. The authors cover a great deal of ground and seem to do it very well. Such is the perversity of human nature, however, that the one point which the reviewer feels like criticizing is one of which the authors pride themselves particularly, namely that all the experiments are quantitative. The reviewer has a distinct fondness for qualitative experiments. They are always quicker and they are often more interesting than the quantitative ones. A student must be taught t o work accurately; but the labor-saving methods have their value even in research, and accuracy to another decimal place is not yet the real goal of the chemWilder D . Bancroft ist. Grundziige der angewandten Elektrochemie. B y Georg Grube. Vol I . pp. x i i 268. Dresden and Leipzig: Theodor Steinkop.ff, 1922. Price: paper, $ I .68; 2.06 bound.-This volume deals with the electro-chemistry 22

X 15 cm;

+

100

New Books

of solutions and is to be followed by a second dealing with the electrochemistry of fused baths and gases and with electric furnaces. The chapters in this volume are entitled: the exact relations between the quantity of electricity and the decomposition products formed a t the electrodes; the ions as carriers of the current in electrolytes; electrical energy from voltaic cells; electrical phenomena a t the surfaces of phases; electrode potentials in electrolytic processes; electrometallurgical processes in aqueous solutions; electrolysis of alkali chloride solutions ; applications of electrolytic oxidation ; some applications of electrolytic reduction; technical electrolysis of water. One interesting case under concentration cells, p. 53, is the one with hydrogen electrodes and two lithium chloride solutions which have the same conductivity and therefore the same concentration of ions. The more concentrated solution is a t the cathode. On p. 81 is an account of Hofmann’s carbon monoxide and oxygen cell, with copper and copper oxide electrodes. The Anaconda zinc process is given, and the reviewer was interested to learn that the electrolytic oxidation of manganate solutions has replaced the chemical oxidation. The author’s method of making sodium plumbate is also interesting. On the other hand the diagram for the Castner soda process goes back to prehistoric days. There is nothing t o show how oxidation of the tannin is avoided in electrolytic tanning and the American work on electrical endosmose, over-voltage, and passivity has been ignored. The book is a fairly serviceable one; but it will not do much t o enhance the reputation of the author. Wilder D. Bancrofl