Abstract
POGGENDORFF'S Annalen der Chemie und Pharmacie, vol. cxl. part 1. —This number contains (1) the first part of an elaborate paper by E. Ketteler, “On the Influences of Ponderable Molecules on the Dispersion of Light, and on the Signification of the Constants in the Mathematical Formulæ for Dispersion” (pp. 1 to 53). This is a critical examination, based chiefly on Mascart's experimental measurements, of the formulæ by which Cauchy and others have endeavoured to connect the indices of refraction of the various kinds of light with their wave-lengths. The nature and scope of the investigation may be gathered from the four following criteria which the author gives as the tests of a satisfactory formula: —“1. A rational formula must enable us to calculate accurately from their wave-lengths the succession of the several colours and their distribution in space, for the whole measured extent of radiation, for some definite density of the dispersive medium. 2. The constants of the formula must be capable of a distinct physical interpretation, analogous to the interpretation assigned by Cristoffel to the constants in his formula. 3. When the density of the dispersive medium is altered, these constants must participate in the change of molecular constitution in some simple manner, corresponding to what has been ascertained in respect to them in the case of gaseous media. 4. Consequently, as the medium approaches the limit of rare-faction, all the indices must approach unity as their limiting value.” The author finds that none of the formulæ hitherto proposed reproduce the experimental results within the limits of error of the measurements, but that this can be done by a formula which he proposes. (2.) “On the Sounds produced by Heated Tubes, and on the Vibrations of Air in Pipes of various Forms,” by C. Sondhaus (pp. 53 to 76). Many experimenters must have observed the frequent production of a musical tone when a bulb has been blown at the end of a rather short and narrow glass tube, the sound beginning just as the tube with the still hot bulb is removed from the lips. This phenomenon formed the subject of an investigation by the author twenty years ago, and he now returns to it in a paper which is to be concluded in the next number of the Annalen. The principal result which he now publishes is that when the dimensions of bulb and tubes are properly proportioned, similar tones can be obtained with heated glass bulbs from which two open tubes proceed in opposite directions. He also gives an empirical formula which expresses approximately the pitch of the tones obtained in terms of the dimensions of the bulbs and tubes; but as this formula does not seem to be based on any physical explanation of the way in which the sounds are produced, and as it takes no account of temperature, the agreement between its results and those of observation must be considered as at least to some extent accidental. Perhaps the remainder of the paper may give further explanations on these points. (3.) “On Chromates,” by C. Freese (pp. 76 to 88), to be concluded in the next part. (4.) “Thermo-chemical Investigations” (continued), by Julius Thomsen (pp. 88 to 114). This section of Professor Thomsen's researches relates to the acids of nitrogen, phosphorus, and arsenic. The thermo-chemical behaviour of these acids, when neutralised with caustic soda, appears to agree in the main with the commonly-received views of their basicity founded upon their chemical properties. (5.) “Further Researches into the Development of Electromotive Force between Liquids,” by Jacob Worm-Müller (pp. 114 to 144). Among other results the author arrives at the following remarkable conclusion: “Solutions of acids and alkalis in equivalent proportions (that is such that equal volumes of the solutions neutralise each other) and of the salts formed by mixing equal volumes of these solutions, do not give rise to electric currents when connected so as to form a circuit.” This paper also is to be concluded in the next number of the Annalen. (6.) “Researches in Electrical Dust-figures,” by Wilhelm von Bezold (pp. 145 to 159). (7.) “On the Law of Formation of Kundt's Dust-figure,” by Theodore Karrass (pp. 160 to 168). (8.) “On an Electrophorus-machine for Charging Batteries,” by Peter Riess (pp. 168 to 172). The author describes a modification of Holtz's electrical machine, which renders it applicable for charging Leyden batteries to a high tension. (9.) “On the Measurement of the Absorption of Light by transparent media by means of the Spectroscope,” by C. Vierordt (PP. 172 to 175). The author's method of measurement consists essentially in diminishing the intensity of each part of a normal spectrum, by means of smoked glasses of known absorptive power and the partial closing of the slit of the spectroscope, until it is identical with that of the light transmitted by the medium to be examined. (10.) “An Observation on the Induction-spark,” by Dr. A. Weinhold (p. 176).
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Scientific Serials. Nature 2, 327–328 (1870). https://doi.org/10.1038/002327a0
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DOI: https://doi.org/10.1038/002327a0