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Sudden Changes in the Solubility of Salts caused by the Formation of two Layers in the Liquid. By H. W. B. RoozeBOOM (Rec. Trav. Chim., 8, 257–272).—In studying the conditions of equilibrium between a dissolved salt and water, a disturbing influence may be introduced, owing to the separation of the liquid into two layers of different concentrations. Cases of this sort are of frequent Occurrence with organic compounds, and have been noticed by Alexéeff (Abstr., 1886, 47). The formation of two layers in a liquid. is a change that is conditioned by temperature, and at certain temperatures it might be possible for the solid salt and the two liquid layers to exist side by side in equilibrium with one another and with the vapour of the liquid. Such temperatures, at which the simultaneous existence of the four phases is possible, would be indicated on the pressure curves as quadruple points (Abstr., 1888, 1511). The author has endeavoured to obtain experimental evidence in this direction, but could find no salt suitable for the purpose. H. C.

Determination of Affinity Coefficients. By W. HECHT, M. CONRAD, and C. BRÜCKNER (Zeit. physikal. Chem., 4, 272-318).— Continuing their determination of affinity coefficients (Abstr. 1889, 931), the authors have examined the actions of sodium methoxide, ethoxide, and propoxide on the iodides of methyl, ethyl, propyl, and heptyl. The coefficients for methyl iodide are found to be in each case much greater than those of the other alkyl iodides, although the latter are also found to decrease somewhat with rising molecular weight. The relation between the coefficients of the iodides depends at the same time on the nature of the metallic salt, as may be seen by the following tables of these relations, in each of which the coefficient of heptyl iodide has been taken as unity.

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On the other hand, the influence of the metallic salt is greatest for the ethoxide and least for the methoxide. This is illustrated by the following table, in which the time in minutes which elapses before one half the active substance has been decomposed is given in each

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In the case of the ethoxide, isopropyl iodide was also examined, and the coefficient found to be much lower than that of the normal compound.

In the latter part of the paper, methods of determining the relation between two affinity coefficients and the values of the coefficients from this relation are discussed. H. C.

Determination of the Affinity of Organic Bases. By J. WALKER (Zeit. physikal. Chem., 4, 319-343).—The author attempted to measure the affinities of the organic bases by studying the influence of their hydrochlorides in accelerating the decomposition of methyl acetate by water. Since the acceleration depends on the amount of free acid in solution, the amount of dissociation of the hydrochloride, and from this the relative affinity of the base for the acid, might be thus calculated. The results obtained were not, however, satisfactory except in the case of very feeble bases. The electrical conductivity was therefore resorted to, and from the conductivities of solutions of equal quantities of acid treated with equal quantities of different bases, the amount of salt formed in each, and from this the affinity of the different bases for the acid was deduced. Both sulphuric and hydrochloric acids were found to give good results by this method; and the results thus obtained for feeble bases agree with those obtained by the method first employed.

The dependence of the affinity of organic bases on constitution is to some extent rendered evident by the results. If methyl or ethyl is substituted for the hydrogen of an amido-group, the compound gains in basic properties. The same thing is also true in the case of the substitution of methyl for hydrogen in the carbon-ring of an aromatic base. On the contrary, the substitution of chlorine or a nitro-group for hydrogen in the carbon-ring considerably decreases the basic character of aniline, this effect being greatest in the ortho- and least in the paraposition. H. C.

Apparatus for Evaporating by the Aid of Heat applied from above. By W. HEMPEL (Ber., 22, 2479—2481).—The author describes, with the aid of a diagram, an apparatus in which small quantities of a liquid can be evaporated by the aid of heat applied from above.

The source of heat is a large, inverted Argand burner, made either entirely of porcelain, or of steatite and metal cemented together with a mixture of soluble glass and finely-divided manganese dioxide. Through the centre of the burner passes a porcelain tube, the lower extremity of which projects a short distance through the flame, the upper extremity being connected with a glass chimney. The crucible or other vessel which contains the substance to be evaporated is placed on a piece of asbestos supported on a moveable iron plate. An inverted beaker, perforated with an aperture just large enough to admit the Argand burner, surrounds the vessel and serves to regulate the supply of heat; if the liquid is evaporated in a basin the employment of the beaker cover is unnecessary.

Clays or fluorides are readily dissolved by the aid of this apparatus.

F. S. K.

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Inorganic Chemistry.

Preparation of Chlorine in a Kipp's Apparatus. By J. THIELE (Annalen, 253, 239-242).-Chlorine may be conveniently prepared in a Kipp's apparatus by the action of hydrochloric acid on bleaching powder. By means of a handpress, the bleaching powder is compressed into a hard cake; this is broken into small lumps and used in this form. W. C. W.

Automatic Apparatus for Evolving Gases from Liquids. By J. THIELE (Annalen, 253, 242-246).-A convenient apparatus for preparing hydrogen chloride from commercial hydrochloric acid or sulphurous anhydride from a concentrated solution of sodium hydrogen sulphite may be made from a three-necked Wolff's bottle. This is provided with (1) a delivery tube fitted with a stop-cock; (2) a small stoppered separating funnel, with the stem drawn out to a fine point; and (3) a safety funnel with some mercury in the bend and a loose plug of cotton wool in the funnel. The Wolff's bottle is half filled with the solution of sodium hydrogen sulphite, for example, and the sulphuric acid is slowly introduced through the separating funnel. W. C. W.

Reciprocal Displacement of Oxygen and the Halogens. By BERTHELOT (Compt. rend., 109, 546-548 and 590-597).-The author summarises his previous work on the reciprocal displacement of oxygen and chlorine and describes some later results.

Pure concentrated fuming hydrochloric acid is not decomposed by oxygen in presence of sunlight, but if some manganous chloride is present the liquid acquires a deep-brown colour, the atmosphere in the flask becomes charged with chlorine, and the liquid has bleaching properties. Oxygen is absorbed and hydrochlorides of manganese perchloride are formed. If the liberated chlorine is removed and hydrogen chloride and oxygen are introduced into the flask, a further quantity of chlorine is set free, and this process may be repeated several times. The decomposition ceases when the hydrates of the hydrochloric acid contain the maximum amount of water; dilute non-fuming hydrochloric acid is not decomposed even after long exposure in presence of manganese chloride. Ferric chloride behaves in the same manner as manganous chloride, but the phenomena are very much less distinct.

The heat of formation of dissolved hydrobromic acid is almost identical with that of water, and hence in presence of water, but under these conditions only, reciprocal decomposition may take place. In presence of excess of water, oxygen readily decomposes hydrogen bromide under the influence of light. Similar decomposition takes place at the ordinary temperature in the case of a fuming solution of hydrobromic acid, that is, hydrates of the free acid not saturated with water, but is arrested almost immediately by the formation of hydrogen perbrom

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ide, HBr; HBr conc. soln. + Br2 gas = HBr, diss. develops +9.2 Cals., the total heat of formation, +43-5 Cals., being greater than the heat of formation of water. Oxygen does not decompose dilute hydrobromic acid, that is, the saturated hydrates of the acid, nor a solution of potassium bromide acidified with hydrochloric acid.

The formation of hydrogen perbromide explains the decomposition of water by bromine, but this change is limited by the dissociation of the perbromide in presence of water.

Dilute solutions of hydriodic acid are readily decomposed by oxygen under the influence of light at the ordinary temperature, the change corresponding with the liberation of 15.9 Cals. for each atom of gaseous iodine.

The heats of formation of dissolved potassium iodide and hydroxide are practically the same, and slight variations in the conditions serve to turn the reaction in one direction or the other. The combination of iodine with potassium iodide in concentrated solution to form potassium triiodide liberates +50 Cals. for each atom of gaseous iodine; the action of iodine on dissolved potassium hydroxide with formation of hypoiodite or iodate liberates +41 Cals. and +54 Cals. respectively for each atom of gaseous iodine. It follows that oxygen will not displace iodine from potassium iodide except under conditions in which potassium triiodide is stable, that is, in very concentrated solutions. Experiment showed that dilute solutions of potassium iodide remain quite colourless when exposed to light for a long time in presence of pure air; very concentrated solutions soon become orange and the colour deepens with prolonged exposure. The liquid then gives a blue coloration with starch and has an alkaline reaction; if, however, it is diluted, it rapidly becomes colourless, owing to dissociation of the potassium triiodide and the action of the liberated iodine on the potassium hydroxide which has been formed.

It is well known that even dilute potassium iodide solutions become yellow when exposed to ordinary air. This is due to the fact that the carbonic anhydride of the air takes part in the reaction. Carbonic acid does not displace hydriodic acid, but the simultaneous action of oxygen and carbonic anhydride on a dilute solution of potassium iodide produces potassium hydrogen carbonate and free iodine, the change being accompanied by the liberation of +13.5 Cals. for each atom of gaseous iodine. The colour of the liquid becomes deeper if the quantity of carbonic anhydride in the atmosphere above it is increased. The action of the oxygen is still greater in presence of acetic or hydrochloric acid, but in these cases the result is in part due to the displacement of some hydriodic acid. Acetic acid liberates very little hydriodic acid, but the action of the oxygen depends on the successive liberation of small quantities. Hydrochloric acid liberates more hydriodic acid and in this case the action of the oxygen is more marked. In presence of a large excess of air, a solution of potassium iodide acidified with hydrochloric acid is completely decomposed by the action of light in a few days.

If manganous chloride is added to a highly concentrated solution of

potassium iodide and the mixture exposed to light, a higher oxide of manganese is precipitated and iodine is liberated; dilute solutions show the same phenomena in a lower degree.

All the reciprocal displacements of oxygen and the halogens under the influence of light are in agreement with the thermochemical determinations. C. H. B.

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Simultaneous Synthesis of Water and Hydrogen Chloride. By P. HAUTEFEUILLE and J. MARGOTTET (Compt. rend., 109, 641—644). -Mixtures which contained oxygen and hydrogen in the proportion required to form water, with varying proportions of chlorine; and mixtures of hydrogen and chlorine in the proportions to form hydrogen chloride, with varying quantities of oxygen, were exploded by means of a spark, and the residual chlorine was determined by means of standard sodium arsenite. If p represents the total hydrogen which enters into combination, and p' the quantity which combines with p — p' gives the ratio of the hydrogen converted into p' water to the hydrogen which forms hydrogen chloride. This ratio is independent of the initial pressure, and of the nature of the spark. It is always less than unity if the proportion of chlorine is more than half the volume of the hydrogen, and it varies with every alteration in the proportion of chlorine. When the volume of chlorine present is double the volume of the hydrogen, the quantity of water formed becomes inappreciable. It is evident that the results do not agree with Bunsen's law.

oxygen,

With equal volumes of hydrogen and chlorine and varying proportions of oxygen, the 'ratio? is always less than unity and does

P' p

not vary greatly when the ratio of oxygen to hydrogen varies from
0.25 to 3. With equal volumes of the three gases the change is re-
presented by the equation 5Cl2+ 5H2 + 502 = 8HCl + H2O + Cl2
+ 402.
C. H. B.

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Equilibrium between Hydrogen, Chlorine, and Oxygen. By H. LE CHATELIER (Compt. rend., 109, 664-667).-The author discusses the results of Hautefeuille and Margottet (preceding Abstract) from the point of view of his own laws of chemical equilibrium. The agreement between the observed and calculated numbers is very close. He points out that the degree of moisture of the gases, which is very important, is not specified. The formula shows that a reduction of initial pressure should be accompanied by a reduction in the proportion of water formed, and the fact that this is not observed indicates that the chlorine is partially dissociated. The varying effects of chlorine and oxygen depend solely on their relative volumes and not on their chemical properties. C. H. B.

Preparation of Oxygen in a Kipp's Apparatus. By J. VOLHARD (Annalen, 253, 246-248).-Small quantities of oxygen can be conveniently prepared in a Kipp's apparatus by the action of hydrogen

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