Journal of the Chemical Society 1898/II. [antikvár]

JOURNAL op THE CHEMICAL SOCIETY. ABSTEACTS OF CHEMICAL PAPERS PUBLISHED IN BRITISH AND FOREIGN JOURNALS. PART II. General and Physical Chemistry. Molecular Refraction and Dispersion of very Dilute Solutions. By D. Dijken {Zeit. physikal. 1897, 24, 81—113).— The refractive indices of a number of dilute salt solutions were determined, and the molecular refraction of the dissolved salt calculated by means of Gladstone's expression; this value . is found to be a constitutive property, as is shown in the appended table. CI. NO3. ÍSO4. NH4—JMg 77 7-8 7'8 NH4—iZn 6-8 6-0 6-0 NH4—Li 7-8 7-1 7-7 NH4—Na 6-7 6-9 6 7 NH4—K 3-4 3'6 3-4 NH4—H 8-0 8-2 8-4 K—Na 3-3 3-3 3-3 The molecular refraction of ammonium chloride is 22 5, of the nitrate 25-8, and of the sulphate (-jSO^) 19-9, and from these values those of the other salts can be readily obtained. L. M. J. Red Spectrum of Argon. By Josef Maria Edee and Eduaed Valenta {Monatsh., 189.5, 16, 893—895).—By means of a concave grating, the spectrum of argon at a pressure of 1—3 mm. was obtained, VOL. LXXIV. ii 1 ABSTRACTS OF CHEMICAL PAPERS. n and the wave-lengths of the lines measured reduced to Eowland' scale. Both the red and blue spectra were obtained, and a table of the wave-lengths of the lines of the red spectrum from 5060 to 3319 is given. The following are given as specially characteristic' X = 4628'56, 4596'22, 4522-49, 4510-85, 4300-18, 4272-27, 4259-42' 4251-25 ; the group 4200-76, 4198-42, 4182-07, 4164-36, and 4158-63: and further, 4044-56, 3949-13, 3834-83. When the dispersion is good' the double line 4191-15—4190-75 should show up plainly in the red spectrum of argon. q Chemistry of the Hottest Stars. By Sir J. Norman Lockyee {Proo. Roy. Soc., 1897, 61, 148—208, and 213).—The author summarises his own investigations and those of others on the spectra of metals at high temperatures and on stellar spectra, and arrives at the following general conclusions. In a mixture of vapours at a particular temperature, a vapour which is not present in sulScient quantity to show all the lines of its spectrum will be represented by the lines which are longest in its spectrum at the particular temperature in question. Only some of the short lines in metallic spectra represent the effects of high temperature. Some of the substances which have been investigated, including iron, calcium, and magnesium, have probably a definite spectrum, consisting of a few lines, which can only - be completely produced at a temperature higher than any which is at present available in laboratory experiments. The lines constituting the new spectra are those which either appear only in the spark spectrum, or are lengthened in passing from the arc to the spark; such lines are termed enhanced lines. In the case of iron, calcium, and magnesium, there are four distinct temperature steps which are marked by spectral changes : (a) The flame spectrum, (6) the arc spectrum, (c) the spark spectrum, {d) a spectrum consisting solely of those lines which are enhanced in passing from the arc to the spark. The order of temperature of certain stars, as determined from a comparison of the extensions of the continuous spectrum into the violet or ultra-violet, is precisely the same as that which follows from a comparison of the metallic spectra at the four stages of temperature. The variations of tbe metallic lines furnish the most convenient means of determining relative stellar temperatures, for the reason that photographs with special exposures are unnecessary. Having ascertained the relative temperature of a star in this way, and assuming that all the absorbing vapours are at the same temperature, the presence or absence of any other metallic substance can be determined by looking for the hues which are longest in its spectrum at that temperature. In the case of the hottest stars, the fourth stage spectrum must be the term of comparison. Accepting the new results with regard to the lines enhanced in the spark, several lines in the spectra of the hottest stars, for which no origins could previously be assigned, can now be ascribed to metallic substances at the fourth stage of temperature. The lines of the cleveite gases appear only in the hotter stars, as indicated by tbe extension of the continuous radiation into the ultra-violet, and they increase in intensity