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Spectra of high-frequency discharges in super-vacuum tubes
CURRENT
TOPICS.
[J. F. I.
Spectra of High-frequency Discharges in Super-vacuum Oct. 8, 1927.)Tubes. R. W. Woon and A. L. LOOMIS. (Natwe, During the summer just passed the authors made a further study of the results obtained by Kirchner and by Gill and Donaldson showing that a brilliant discharge is given by a tube exhausted to a nonconducting vacuum, provided that the excitation be applied through external electrodes and that the frequency be that of a six- or sevenmetre wave. Under these conditions even a low voltage suffices. The tubes of the .American workers were “ drastically ” cleaned, dried and exhausted with a molecular pump, the walls being heated. Through the vacuum thus reached an induction coil giving a twoinch spark sent no discharge. When, however, an oscillating circuit with wave-length of three metres was connected to external tinfoil electrodes a brilliant blue discharge appeared. This showed the hydtrogen spectrum. If the pump continued to exhaust the tube with the blue discharge this gradually disappeared and was replaced by “ the olive-green discharge characteristic of pure oxygen, while the tube walls phosphoresced with a very brilliant ruby-red light.” Further pumping and excitation made the oxygen spectrum derived from the previoas discharge to disappear. A pair of prominent carbon lines alone persisted from many lines of that element that had occurred1 along with the oxygen lines. The red phosphorescence above described manifested itself with tubes of quartz, soft glass, and pyrex glass. One of the authors using a tube that showed the red effect only feebly under excitation by a seven-metre wave-length found that the application of a thirty-metre wave-length caused a “ Using one electrode only, we found that a much brighter glow. magnet brought close to the walls, caused a concentration of the red glow on the near side of the tube, the deflection of whatever caused the phosphorescence of the glass indicating negative electrons moving away from the electrode. At the other end of the tube, the magnet repelled whatever caused the glow to the further wall of the tube, indicating electrons moving toward the electrode. We believe that phosphorescence is associated in some way with the presence of positive ions of oxygen but the exact mechanism of its production has not been ascertained.” G. F. S. X-ray
Diffraction in Liquids. C. V. RAMAN and C. M. Oct. 8, 1927.)-A marked difference has been found in the haloes obtained by applying X-rays to aromatic liquids according to the “ form, position and mass of the substituent groups which replace the hydrogen atoms in benzene. Ortho-, para- and meta-compounds are readily distinguished by their X-ray liquid A reproduction of the diffracti,on haloes of aniline and haloes.” nitrobenzene is given in which the white spot in the centre is larger and more diffuse for the latter compound. The halo of mercurv agrees with predictions based on its having the smallest compress;bility of all known liquids. G. F. S. SOGANI.
(Nature,
TOPICS.
[J. F. I.
Spectra of High-frequency Discharges in Super-vacuum Oct. 8, 1927.)Tubes. R. W. Woon and A. L. LOOMIS. (Natwe, During the summer just passed the authors made a further study of the results obtained by Kirchner and by Gill and Donaldson showing that a brilliant discharge is given by a tube exhausted to a nonconducting vacuum, provided that the excitation be applied through external electrodes and that the frequency be that of a six- or sevenmetre wave. Under these conditions even a low voltage suffices. The tubes of the .American workers were “ drastically ” cleaned, dried and exhausted with a molecular pump, the walls being heated. Through the vacuum thus reached an induction coil giving a twoinch spark sent no discharge. When, however, an oscillating circuit with wave-length of three metres was connected to external tinfoil electrodes a brilliant blue discharge appeared. This showed the hydtrogen spectrum. If the pump continued to exhaust the tube with the blue discharge this gradually disappeared and was replaced by “ the olive-green discharge characteristic of pure oxygen, while the tube walls phosphoresced with a very brilliant ruby-red light.” Further pumping and excitation made the oxygen spectrum derived from the previoas discharge to disappear. A pair of prominent carbon lines alone persisted from many lines of that element that had occurred1 along with the oxygen lines. The red phosphorescence above described manifested itself with tubes of quartz, soft glass, and pyrex glass. One of the authors using a tube that showed the red effect only feebly under excitation by a seven-metre wave-length found that the application of a thirty-metre wave-length caused a “ Using one electrode only, we found that a much brighter glow. magnet brought close to the walls, caused a concentration of the red glow on the near side of the tube, the deflection of whatever caused the phosphorescence of the glass indicating negative electrons moving away from the electrode. At the other end of the tube, the magnet repelled whatever caused the glow to the further wall of the tube, indicating electrons moving toward the electrode. We believe that phosphorescence is associated in some way with the presence of positive ions of oxygen but the exact mechanism of its production has not been ascertained.” G. F. S. X-ray
Diffraction in Liquids. C. V. RAMAN and C. M. Oct. 8, 1927.)-A marked difference has been found in the haloes obtained by applying X-rays to aromatic liquids according to the “ form, position and mass of the substituent groups which replace the hydrogen atoms in benzene. Ortho-, para- and meta-compounds are readily distinguished by their X-ray liquid A reproduction of the diffracti,on haloes of aniline and haloes.” nitrobenzene is given in which the white spot in the centre is larger and more diffuse for the latter compound. The halo of mercurv agrees with predictions based on its having the smallest compress;bility of all known liquids. G. F. S. SOGANI.
(Nature,