General and physical chemistry
Journal of the Chemical Society Abstracts
Nature, 1921, 108, 272-274 ).-A periodic relationship is known to exist between the atomic volumes of elements in combination, the differences between the atomic volumes of successive members of the same series being of the order of that of hydrogen. Similar serial and group relations are observed with the atomic refractivities, the serial differences again being of the order of the atomic refractivity of hydrogen. When the atomic volumes of carbon, nitrogen, oxygen, fluorine, silicon,
... s, sulphur, chlorine, arsenic, selenium, bromine, and iodine are plotted against their atomic refractivities, the points obtained lie approximately on a straight line. Molecular Refraction of some Molten Salts and their Degree of Dissociation. G . MEYER and HECK (2. Elektrochem., 1922, 28, 21-23).-The molecular refraction of molten sodium hydroxide and nitrate and potassium hydroxide and nitrate has been measured a t a series of temperatures between 320" and 440". The method adopted was to allow a ray of light (sodium) to fall into a prism of the molten substance and be reflected from a metallic mirror inside the prism. The densities of the molten salts were determined for all the temperatures used. The mean molecular refraction over the whole temperature range is found to be : sodium nitrate 11-54, potassium nitrate 14-09, sodium hydroxide 5-37, and potassium hydroxide 7-71. These values, which are accurate to one unit in the second decimal place, the refractive index being accurate to one unit in the third decimal place, are in good agreement with the values calculated from the atomic refractions. Using the values 2.80 and 2.59, respectively, for the atomic refractions of the sodium atom and the sodium ion, it is calculated that molten.sodium nitrate is dissociated to 6107%. The influence of temperature on the molecular refraction of all the substances examined is very small. F. W. ASTOX and R. H. FOWLER (Phil. Mag., 1922, [vi], 43, 514--528).-A mathematical discussion of some points raised by the performance and further design of the mass spectrograph. J. FRANCK (Festschrift Kaiser Wilh. Ges. Ford. Wiss. Zehnjkhtrigen Jubilaum, 1921, 77-Sl).-A summary of the manner in which the broadening of spectral lines has been explained, or is capable of explanation, both by classical methods and in terms of the quantum theory. Radiation damping has been fairly adequately explained on the quantum (Science, 1921, 54, 305--306 ).-When calcium wires are exploded by the Anderson method (Astrophys. J . , 1920, 51, 37), i t is found that, as the size of the wires employed is decreased, the energy of the stimulus remaining the same, the intensity of the enhanced lines is increased, indicating a more complete ionisation of the calcium atoms. A fine asbestos fibre about 3 em. in length was therefore saturated with an aqueous Published on 01 January 1922. Downloaded on 25/10/2014 14:57:47. View Article Online GENERAL AND PHYSICAL CHEMISTRY. ii. 243 solution of a calcium salt, and the charge of the high-tension condensers thrown across it. The fibre remained uninjured, and the calcium spectrum thus produced showed a striking enhancement of the spark lines of calcium over the arc lines, indicating that a large proportion of the emitting atoms were ionised. A table giving the relative intensities, under various conditions, of prominent spark-and arc-lines of calcium shows that the new source of light, provisionally called the " super-spark," yields a degree of ionisation comparable with, or perhaps in excess of, that existing in the high chromosphere of the sun and in the early (or hot) type B stars. Very minute amounts of material suffice for the production of intense spectra by this method, and practically only metallic lines are produced; the spectra of hydrogen, oxygen, or of the acid radicle of the salt used do not appear, and only the strongest air lines could be observed.