General and physical chemistry
Journal of the Chemical Society Abstracts
Determination of Refractive Indices of Hydrogen, Carbon Dioxide, and Oxygen in the Infra-red. JOHN KOCH ( A m . Physik, 1905, [ iv], 17, . --,4n interference method is employed and details are given. For hydrogen for a wave-length = 8*69p, the value 1.0001373 a t 0' and 760 mm. was obtained, a result in accord with the value 1.000264 obtained by Boltzmann for the dielectric constant. From the values of the
... values of the refractive index for this and other wavelengths, the author deduces by Drude's equations (ibid" 1904, 14, 677 and 936) the value 1.49 x 107 for the ratio elm. For carbon dioxide for the same wave-length, the value 1.0004578 was obtained; this is greater than that for the B-line, so that the gas furnishes a case of anomalous dispersion. For oxygen, the value found was 1*0002661, which is less than the values hitherto obtained for the lithium and D-lines (1.000271), so t h a t the dispersion is normal. L. M. J. Relation between Electrolytic Dissociation and Refractive Power. PILIPPO ZECCHINI (Gaxnetta, 1905, 35, ii, 65--86).-The auCuhor has made a large number of measurements or" the densities and refractive indices for sodium light and a t the ordinary temperature of solutions of different concentrations of sulphuric, hydrochloric, nitric, acetic, propionic, trichloroacetic, phosphoric, phosphorous, and hydrofluoric acids, sodium and potassium hydroxides, ammonia, potassium nitrate, chloride, acetate, and trichloroacetnte, and ammonium nitrate. The numbers obtained lead to the following conclusions. The dissociation of sulphuric acid by dilution with water effects only a very sniall change in the molecular refraction of the acid. W i t h hydrochloric and nitric acids, the molecular refraction increases slightly with the dilution. The increase scarcely ever amounts to 2.2, which should be the value corresponding with the complete ionisa t ion of n hydrogen atom. Leblanc and Rohland's hypothesis, according to which the hydrogen ion has double the refraction of the hydrogen atom, is therefore regarded by the author a s not justified, the small deviations ol the molecular refraction being equally well attributable t o the anion. The values obtained for solutions of the bases examined indicate no difference in refraction between a hydroxyl group and a hydroxyl ion. I n the case of salts, the molecular refraction is mostIy independent of the concentration of the solution. The molecular refraction of the water formed in the neutralisation of a n acid by a base varies considerably. For the strong acids (nitric, hydrochloric, sulphuric, and trichloroacetic) with the strong bases, potassium and sodium hydroxides, it varies from a minimum of 7-71 with sodium sulphate to a maximum of 8.40 with potassium trichloroacetate, whilst it has the value 5-87 for ammonium nitrate or potassium acetate. No explanation is advanced for these divergences. from Mebereol. Zeit., 22, 102-1 13) .-A measured amount of potassium durn solution is added to 1 litre of the water under examination and precipitated with ammonia. The radioactivity of the emanation and the induced radioactivity, which are all collected in the precipitate, are determined together i n a n apparatus resembling that of Elster and Geitel, and are found generally to lie between the activity of radium and t h a t of thorium. Rain is always slightly active, most so that collected during a thunderstorm in the spring, or in a town ; the activity diminishes as the rain shower continues ; freshly fallen snow is 3-5 Chemiluminescence.