General and physical chemistry
Journal of the Chemical Society Abstracts
Absolute System of Colours. 11. WILHELM OSTIVALD (Zeitsch. physikal. Chem., 1917, 92, 222-226. Compare A., 1916, ii, 205).-The genera1 equation expressing colour in the author's system involves three terms connected by the relation 7 + w + s = 1, where T refers to a pure colour, 'zu represents white, and s black. The determination of the pure colour factor T in ternis of the frequency of light in the visible spectrum is discussed, and a table is given showing the relation between the frequency
... ween the frequency and the classification of the various colours according to the author's system. H. M. D. Determination of the Spectrum of a Univalent Polyatomic Ion, and in Particular of the H', Ion. J. STARK (Anrz. Physik, 1917, [iv], 52, 221-254).-1n a further attempt t o differentiate the carriers which are responsible for the spectra which are emitted under different conditions, it has been found that the many-lined spectrum of hydrogen is to be attributed to diatomic hydrogen ions carrying a single positive charge. The spectrum in question is excited in greater intensity by low-speed cathode rays (20-50 volts), whereas the canal rays give rise to a very feeble emission of the many-lined spectrum. It is not yet known whether the visible spectrum attributable t o the H,' ions is accompanied by a characteristic emission in the ultra-red o r in the ultra-violet. The above-mentioned spectrum of the univalent diatomic hydrogen ion is discussed in reference to the spectra emitted by the univalent, monatomic hydrogen ion, the hydrogen atom, and the hydrogen molecule. tion of an Electron with a Positive Ion. J. STARK ( A m . Physik, 1917, [iv], 52, 255-275).-The fact t h a t hydrogen gives rise to a continuous spectral emission in the near ultra-violet has been noted by several observers, b u t the conditions under which this is obtained have not previously been submitted to investigation. New experiments show that there are two continuous hydrogen spectra, one of which is situated in the ultra-violet a t about h 2500 and the other in the bluish-violet region. The emission phenomena in question are associated with the presence of positively charged ions in the gas, the bluish-violet spectrum being connected with the H,' ion and the ultra-violet with the H' ion. The intensity of the two spectra is greatest under conditions in which combination between electrons and positive ions is of greatest frequency. The bluish-violet emission is accordingly of high intensity in the blue layer a t the commencement of the positive column, whilst the ultra-violet continuous spectrum is emitted in high intensity by the hydrogen canal rays. Continuous spectra are also emitted by the vapours of the alkali and alkaline earth metals, cadmium, and mercury, and in these cases also thO emission is dependent on the presence of positively charged met'al ions. The frequency with which these ions combine with electrons determines the intensity of the continuous spectra, and these are accordingly emitted by the positive column in glow discharge through the vapour, and in the case of the alkali and alkaline earth metals by the Bunseii and oxyhydrogen flames in which the vapours are present. It is suggested that all the elements will probably give rise to a continuous emission spectrum of the above-mentioned type under favourable conditions. According to the nature of the element, this spectrum may be situated in the visible, ultra-red, or ultraviolet region. € I . 151. D. Spectroscopic Observations on the Active Modification of Nitrogen. V. Hon. R. J. STRUTT (Proc. Roy. Soc., 1917, [ A ] , 93, 254--267).-The faint red bands A 6394.45, A 6468.53, A 6544.81, and h 6623.52 observed in the spectrum of the nitrogen afterglow have been further examined under conditions which preclude the possibility that they are to be attributed to the light of stray discharges in the obse;.-vation tube. These bands, which belong to the a-group, are found in undiminished intensity when stray electric discharges are rigidly excluded, and are theref ore characteristic of the afterglow spectrum. The Pand y-groups of bands appear in most cases with the same relative intensities, and i t has been previously suggested that they are both due to oxides of nitrogen. The brightness of the visual afterglow (a-group) is enhanced in presence of small quantities of other substances which act as catalysts, and it is found that those substances which yield oxygen increase the intensity of the P-group, whilst catalysts which do not yield oxygen brighten up the visual afterglow, but have no influence on the intensity of the Pand y-groups of bands. By subjecting the nitrogen used to the actJon of a concentrated alkaline solution of pyrogallol and of phosphoric oxide in order t o remove oxygen, carbon dioxide, and water as far as possible, it has been found that the intensity of the Pand y-groups of bands is greatly reduced. From experiments with nitrogen purified in this manner, it appears that t*he addition of oxygen or nitric oxide to the afterglow brings out the 8-and y-bands with a certain relative intensity. The addition of carbon dioxide gives greater relative intensity to the 8-bands and carbon monoxide t o the y-bands. The addition of sufficient quantities of nitric oxide or nitrogen peroxide to the afterglow causes the Band y-groups to disappear, and a visually greenish, continuous spectrum is then obtained. The same spectrum, together with the y-, but not the fl-group, appears when nitric oxide is passed into a blow-pipe flame. The introduction of oxygen into the afterglow is not accom-GENERAL AND PHYSICAL CHEMISTRY. ii. 283 panied by any measurable oxidation, and for this reason it does not seem possible t o attribute the Pand y-groups of bands to nitric oxide. H. M. D. A . DAUVILLIER (Compt. ?-end., 1917, 1 6 4 , The L-Series of the Elements of High Atomic Weights. R. LEDOUX-LEBARD and 687-690. Compare Moseley, A., 1914, ii, 14; and Barnes, A., 1915, ii, 658).-A study of the L-series of radiations in the cases of tungsten, iridium, platinum, and gold. The series comprises nine rays, which occur independently of the mode of generation of the electrons. The results verify the law v=A(iV-7*4)2, v being the frequency, N the atomic number of the radiator, and A a constant. Plotting N against .\/< all the rays of the series appear t o lie on st,raight lines, but the homologous rays of the central part of the series are not similar in intensity. The intense rays for tungsten are numbers 4 and 6, and for iridium, platinum, and gold 4 and 5. W. G. Quantitative Absorption Spectra. 11. A New Ultraviolet Photometer. FREDERICK RUSSELL LANKSHEAR (iklevz. Man-Chester PhiZ. SOC., 1916, 6 0 , No. 10, 1 -4 . Compare A., 1915, ii, 605).-The photometer described is of the sector type, differing from previous instruments, however, in that the sector has a single semicircular aperture the diameter of which passes through the centre of the circular sector. By means of a disk with a corresponding aperture, which rotates on the face of the sector wheel, the aperture of the sector may be varied a t will. The Ultra-violet Transparency of certain Coloured Media. H. W. L. ABSALOM (Phil. Mag., 191'7, [vi], 33, 450-455). -In the search f o r a substance opaque to the yellow region but transparent to the ultra-violet portion of the spectrum, the author has examined a number of coloured minerals and precious stones. Blue rock-salt from Stassfurt was found t o transmit ultra-violet rays down to ~2 2 5 0 , and the same degree of transparency was found for sylvite and for rock-salt and sylvite which had been coloured by the action of cathode rays. Since the colour of blue rock-salt has been attributed to colloidal sodium, the investigation was extended to the blue solutions of metals in liquid ammonia. The most stable of these is the blue magnesium solution, which was found to transmit ultra-violet rays down to ~2 4 4 2 . The limit of transmission for liquid ammonia is h 2393. These results would seem to ghow that ultra-violet transparency in a coloured mineral is favourable to th8 view that the colour is to be attributed to the presence of a colloidal metal.