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New Fluorescences with Well-defined Spectra. By L. DE BOISBAUDRAN (Compt. rend., 105, 258-261, 301-304, 343-348).— Mixtures of alumina with samarium oxide, ZaO3, or ZẞO3, treated with sulphuric acid and calcined, give fluorescences the spectra of which are characterised by a large number of well-defined lines and bands instead of by one or a few nebulous bands as is usually the case. Calcination at a very high temperature greatly increases the brilliancy of the fluorescences. The positions and characters of the bands and lines are described in detail.

rescences.

Mixtures of alumina with uranium oxide give no fluorescence at all, and lanthanum and yttrium oxides give no well-marked fluoAlumina and ytterbium oxide give a blue fluorescence, the spectrum of which consists of four bands, which are also observed in the fluorescences of mixtures rich in ytterbium and thulium, or erbium and thulium, and which therefore may be attributed to thulium or to a new element.

Mixtures of alumina with oxides of cerium, erbium, thulium, dysprosium, and gadolinium, have also been examined, and their fluorescences will be described in detail in a subsequent paper.

C. H. B.

Spectra of Didymium and Samarium. By E. DEMARÇAY (Compt. rend., 105, 276-277).-The author has previously stated that the band at 4690 varies in intensity during the fractionation of praseodymium, and he concluded that the band was not due to praseodymium. The fact is confirmed but the conclusion is withdrawn. The purest fractions of praseodymium containing only small quantities of lanthanum show a strong nebulous band at about 4690, which, however, is very different in character from the band previously referred to, and it follows that there are two bands of very similar wave-length, but of different character, one being due to praseodymium and the other to some other element at present unknown.

Neodymium free from praseodymium and containing only a very little samarium, gave a spectrum in which the following bands not previously described were observed. A somewhat narrow band at about 4640 on the less refrangible side of a nebulous didymium band; a narrow and somewhat feeble band at 4300; and in a nitric acid solution a band at 4760, which really consists of two lines at 4734 and 4768 respectively, the more refrangible being the more intense. This double line is seen with pure neodymium.

The author anticipated Kruss, Nilson, and Gerhardt, in the discovery of the compound nature of samarium (Abstr., 1886, 837; and this vol., p. 551). C. H. B.

Development of Voltaic Electricity by Atmospheric Oxidation. By C. R. A. WRIGHT and C. THOMPSON (Proc. Roy. Soc., 42, 212-216).—The authors have observed that when metallic copper immersed in aqueous ammonia is exposed to a limited supply of air, the metal dissolves chiefly as cuprous oxide. This action, which the authors regard as in all cases the primary action, is very slow when the liquid is kept perfectly at rest; but it can be greatly

accelerated by arranging horizontally near the surface of the liquid a plate, termed the "aëration" plate, of platinum or other conductor not acted on under the circumstances, and joining this to the copper by a wire. When connection is made through a galvanometer, it is found that a current is generated during the action. The voltaic element thus formed polarises rapidly unless the external resistance is very high. Its electromotive force varies from 0.5 to 06 volt, and increases with the concentration of the ammonia solution, or when sodium or ammonium chloride is added thereto, or when spongy platinum is substituted for the platinum plate. In the latter case, and with strong ammoniacal brine, it may amount to 0.8 volt, nearly equalling that due to the heat of formation of cuprous oxide (40810), or 0.88 volt.

This battery has a close connection with the air battery of Gladstone and Tribe (this Journal, 1873, 582), which consists of copper in solution of cupric nitrate, and an aëration plate formed by a trayful of crystals of silver nitrate. Cuprous oxide is here deposited on the aëration plate, whilst in the author's cell it is formed at the surface of the copper. This has been proved by means of a battery of special construction. After continued action, copper was found only in the liquid surrounding the copper plate.

The authors are continuing these experiments, and have found that metals not otherwise prone to oxidation (mercury, silver) may be similarly dissolved in appropriate liquids.

CH. B.

Alteration of Carbon Electrodes used for the Electrolysis of Acids. By H. DEBRAY and PÉCHARD (Compt. rend., 105, 27—30).— The battery used consisted of four Bunsen cells, and the electrodes had been purified by treatment with chlorine. When hydrochloric acid is electrolysed with carbon electrodes, the gas evolved at the positive pole is a mixture of chlorine, carbonic anhydride, and oxygen; in the case of sulphuric acid it is a mixture of oxygen and carbonic anhydride; and in the case of nitric acid a mixture of nitrogen oxides and carbonic anhydride. In all cases, the positive electrode undergoes disintegration, and the black powder which is formed, after being washed and dried in a vacuum, deflagrates at a temperature below a red heat, with evolution of carbonic anhydride and carbonic oxide. When nitric acid has been electrolysed, the gas also contains nitrogen.

The products were analysed by causing them to deflagrate in a vacuum, and collecting the water and oxides of carbon evolved. The deflagrated matter was then heated to bright redness in a porcelain tube, and the gas given off was collected and analysed.

The amount of water and oxygen contained in the product varies with the nature of the acid electrolysed and its degree of concentration. The proportion of oxygen is sometimes as high as 9 to 10 per cent., and that of water as high as 8 per cent.

In the case of hydrochloric acid, no soluble organic compound is formed. C. H. B.

Conductivity of Bismuth for Heat in a Magnetic Field. By A. RIGHI (Compt. rend., 105, 168-169).-The conductivity of bis

muth for heat varies in a magnetic field in the same ratio as its electrical conductivity, and the isothermal lines undergo rotation in the same manner as the equipotential lines. C. H. B.

Comparative Radiation of Fused Platinum and Fused Silver. By J. VIOLLE (Compt. rend., 105, 163-165).-The total radiation of melting platinum as measured by means of a smoked thermopile is 54 times as great as the total radiation of an equal surface of melting silver. This ratio is much less than that of the luminous intensities of the two metals. C. H. B.

Heat of Formation of Hydrogen Telluride. By BERTHELOT and FABRE (Compt. rend., 105, 92-95).-Tellurides of zinc, iron, and the alkalis do not yield pure hydrogen telluride. Better results are obtained with the tellurides of calcium, barium, and magnesium, especially the latter. Magnesium telluride is obtained by heating a mixture of the two elements to dull redness when combination takes place with great violence. A better method is to pass telluriumvapour over magnesium heated in an atmosphere of pure hydrogen. The telluride is a white, flocculent substance, which alters very readily on exposure to air, and yields pure hydrogen telluride when treated with hydrochloric acid. The gas is very unstable even in the dark, and decomposes at once in contact with moist air. It is completely absorbed by potash. Its odour is different from that of hydrogen sulphide or selenide, and slightly resembles that of hydrogen arsenide, and its action on the animal economy is very much less irritating than that of the selenide. Its solution in alkalis is colourless, but becomes blue iu presence of a trace of oxygen, tellurium being precipitated if the oxygen is in excess.

Hydrogen peroxide decomposes hydrogen telluride with formation of water and liberation of tellurium, but part of the latter undergoes oxidation. The reaction with ferric chloride is, however, very definite, and it was therefore used in the thermochemical measurements. The heat developed by the reaction (TeH, 130) is 58-24 Cal., from which it follows that

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H2 gas Te cryst. TeH2 gas absorbs -350 Cal.

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The heats of formation of water, hydrogen sulphide, and hydrogen selenide, are respectively +59'0, +46, and - 123 Cal., and it is evident that in the oxygen-group, as in the chlorine-group, the energy of combination with hydrogen diminishes as the atomic weight of the element rises. C. H. B.

Heat of Formation of Crystalline Tellurides. By C. FABRE (Compt. rend., 105, 277-280).-Tellurides can be prepared by passing the vapour of tellurium over the metal, or by heating the finelydivided metal with tellurium in an atmosphere of hydrogen. Ferrous telluride forms steel-grey crystals which scratch glass; cobalt telluride forms brownish crystals; nickel telluride forms small, reddishgrey crystals; thallium telluride resembles galena in appearance, but rapidly tarnishes in the air and is readily powdered. These tellurides

are not affected by cold hydrochloric and sulphuric acids, but slowly alter in moist air.

All the tellurides dissolve readily in bromine-water and bromine, with formation of hydrogen bromide, a metallic bromide and tellurous acid. This reaction was utilised for the determination of the heats of formation of the tellurides, and the numbers given in the following table are the heats of formation of the crystallised compounds from crystallised tellurium and the solid metal. The heats of formation of the selenides are given for comparison.

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The heats of formation of the tellurides are lower than those of the corresponding selenides.

C. H. B.

Values of the Heats of Combustion of Organic Compounds Determined by Different Methods. By F. STOHMANN (J. pr. Chem. [2], 36, 131-141).-A comparison of the results obtained by the author in his various researches with those published by Berthelot in conjunction with Vieille, Louguinine, and Recoura. A determination of the heat of combustion of naphthalene by Berthelot's method of combustion in compressed oxygen has given the value 1231-5 cal. W. P. W.

Passage from the Benzene Series to the Acetic Series. By BERTHELOT and RECOURA (Compt. rend., 105, 141-145).-A further connecting link between the two series is furnished by the fact that quercite and inosite can both be converted into quinone.

Quercite.-Heat of combustion, 1 gram 4:330 Cal.; per gram-molecule at constant volume, +7101 Cal.; at constant pressure, 709-8 Cal. Heat of formation (crystallised), +268-2 Cal.

Inosite.-Heat of combustion, 1 gram 3.703 Cal.; per gram-molecule at constant volume and pressure, +666 5 Cal. Heat of formation, +3115 Cal. These values are slightly higher than those for glucose. Quinic Acid.-Heat of combustion, 1 gram 4:342 Cal.; per grammolecule, +833-7 Cal. Heat of formation (crystallised), +238:3 Cal. The union of quercite with two atoms of oxygen to form inosite would develop +433 Cal., a number intermediate between the heat of conversion of benzene into phenol (366), and of phenol into quinol (+52-2). The formation of quinic acid and water by the union of quercite and formic acid would develop +53·9 Cal., a number comparable with the heat developed by the similar reaction between phenol and formic acid (+36-6). The conversion of inosite into quinone by removal of 4 mols. water would develop +97 Cal., and hence this is a case of dehydration with change of function, but with

out condensation, accompanied by development of heat. The conversion of quercite into quinone by removal of 3 mols. H2O would develop +249 Cal., and the conversion of quinic acid into hydroxybenzoic acid by a similar reaction would develop +987 Cal. The condensation of acetylene to benzene develops +171.0 Cal.

In all cases, the conversion by dehydration of compounds belonging to the acetic acid series into compounds of the benzene series is accompanied by a development of heat, or in other words by a loss of energy, which corresponds with the increased stability acquired by the nucleus of the fundamental hydrocarbon. C. H. B.

Boiling Points of Salt Solutions. By G. T. GERLACH (Zeit. anal. Chem., 26, 413-530).-The author has carefully redetermined the boiling points of solutions of about 40 salts, acids, and alkalis, making in each case a series of observations on solutions of different strengths. With the majority, the formation of a crust during ebullition begins a little below the highest temperature attainable. In the case of salts which crystallise with water of crystallisation, the salting out which occurs on further evaporation is accompanied by a fall of temperature, which in some cases is very considerable. The crystalline magma obtained by salting out sodium sulphate at the boiling point has been observed to boil at 72°, while the escaping steam showed 100°. If in a constant amount of water equal quantities of salt are successively dissolved, the differences in the boiling points invariably decrease, but if in the case of salts which crystallise with water of crystallisation, only the anhydrous salt is considered, the differences between the boiling points for equal increments of salt increase at first, and only begin to decrease when stronger solutions with higher boiling points are reached. This points to the existence, in the weak solutions, of compounds of salt and water acting as a single substance, even at the boiling temperature, and to the dissociation of these hydrated molecules at the higher boiling points.

By laying down the boiling points in curves, it is seen that when equal weights of the salts are regarded, the curves for different substances follow no regular law, and frequently cut one another. With equal equivalents (molecular weight divided by the valency of the metal) the curves of salts of the same group and similar constitution

never cut.

No direct connection can be traced between the molecular weights of the dissolved substances and the boiling points of their solutions, nor between specific gravity or specific heat and boiling point. On the other hand, in most cases, solutions of highly soluble salts boil at higher temperatures (for equal molecular concentration) than those of lower solubility. Also those salts which in the act of dissolving produce the smallest amount of contraction are almost invariably those which for equal molecular concentration show the highest boiling points. Ammonium salts are the chief exceptions to both these laws. Tammann's law that for a given temperature the lowering of the vapour-tension produced by dissolving one molecule of a salt in an invariable quantity of water is equal for salts of similar constitution, is not borne out by the author's observations. M. J. S.

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