CHEMICAL ABSTRACTS ISSUED BY THE BUREAU OF CHEMICAL ABSTRACTS 1929 A. PURE CHEMISTRY BUREAU [Representing the Chemical Society and the Society of Chemical Industry] Offices of the Bureau: CENTRAL HOUSE, 46, FINSBURY SQUARE, LONDON, E.C. 2. A.-PURE CHEMISTRY JANUARY, 1929. General, Physical, and Inorganic Chemistry. Spectrum of doubly-ionised nitrogen (N III). L. J. FREEMAN (Proc. Roy. Soc., 1928, A, 121, 318343). The spectrum was examined from a 8000 to λ 850. The Nш lines observed are tabulated and their positions compared with those found by calculation. J. L. BUCHAN. Structure of the band spectrum of helium. V. W. E. CURTIS and A. HARVEY (Proc. Roy. Soc., 1928, A, 121, 381-401; cf. A., 1928, 449).-Details are given of four new bands and of one of the "ordinary orthohelium family. The new bands are: 3D(1) →→ 2P(1) of o-He, near λ 5750; 3X 2P of p-He near 2 6250; 3Z 2P of o-He2, and 4Z - 2P of o-He. These last two bands are very similar to 3Z 2P of p-He, near λ 6300, which is also described. J. L. BUCHAN. Hyperfine structure in the arc spectrum of cæsium and nuclear rotation. D. A. JACKSON (Proc. Roy. Soc., 1928, A, 121, 432-447). The cæsium vapour was mixed with helium at about 2 mm. pressure in a discharge tube and excited by external electrodes. It was necessary to warm the tube in order to obtain the cæsium spectrum, chiefly the 18-3p lines, and at the same time that due to helium was extinguished. On raising the temperature the yellow, red, and infra-red lines of cæsium develop and those of the principal series become broader and blurred, their hyperfine structure being extinguished. In the principal series the lines were close doublets of equal intensity. Tables of measurements are given and those lines found to be simple are also tabulated. The results are discussed and a theory is put forward to account for the doublets. J. L. BUCHAN. Absorption bands in the spectrum of cadmium vapour. A. JABLONSKI (Bull. Acad. Polonaise, 1928, A, 163–170).-The absorption spectrum of cadmium vapour has been investigated with a view of finding the positions of bands corresponding with the fluorescence bands, and to show that both series have the same convergence point. The apparatus used is described. The frequency of the bands is plotted against the difference of frequency between one band and the next, and it is found on extrapolating the curve that the point of convergence of the bands is at a wave-length of 2561 Å. Assuming that this is connected with the dissociation of the cadmium molecule, Cd, and activation to the state 23P1 of one of the atoms resulting from the dissociation, the energy of dissociation of the cadmium atom is calculated to be 1.035±0.031 volts, a value in good agreement with that calculated by consideration of the system Cd II (1.023+0.006 volts). The absorption spectrum of cadmium shows a great predominance of continuous absorption over band absorption, an observation which shows the existence of metastable states of long duration. It seems probable that the only essential difference between the molecules of cadmium (and mercury) and other diatomic molecules (e.g., iodine, selenium, tellurium, etc.) consists in the existence of metastable states of these molecules. A. J. MEE. Origin of the band λ 2476·3-2482-7 in the spectrum of mercury. S. PIENKOWSKI (Bull. Acad. Polonaise, 1928, A, 171-179).-The band of wave-lengths 2482-72-2476-35 Å. has been resolved into rays which can be arranged in a series of seven doublets. In each of the branches of these doublets there is an irregular ray; the displacement occurs for the same quantum number in both branches and in opposite directions. The moment of inertia of the molecule emitting the light is calculated and it is concluded that the band is due to a mercury hydride, trace of water vapour. All photographs of spectra the hydrogen having been supplied probably by a of hydrogen and mercury vapour show the presence of the band. A. J. MEE. Wave-lengths and Zeeman effects in yttrium spectra. W. F. MEGGERS (U.S. Bureau Stand. Res Paper No. 12, 1928, 319-341).-The wave-lengths corresponding with approximately 1000 lines photographed in the arc and spark spectra of yttrium were measured relative to secondary standards in the iron spectrum, the values extending from 2127.99 Å. in the ultra-violet to 9494-81 Å. in the infra-red. Four classes of lines were distinguished; about 500 are ascribed to neutral atoms and constitute the YI spectrum; 240 originate with singly-ionised atoms, the Y spectrum; 10 belong to doubly-ionised atoms, the Y П spectrum, and most of the remainder describe the band spectrum characteristic of molecular compounds, presumably yttrium oxide. Tables are given of the wave-lengths, line intensity estimates, wave numbers, and classification. Measurements of Zeeman effects for 220 lines from 3173 to 6896 Å. included. N. M. BLIGH. are Spectra of mercury at atmospheric pressure. W. H. CREW and L. H. DAWSON (J. Opt. Soc. Amer., 1928, 17, 261-270).-The light emitted from a mercury arc in quartz was photographed through a quartz spectrograph. As the current through the arc was increased the lines of the line spectrum |