Professor Dewar on Phosphorescence and Photographic Action. was taken at ordinary temperature. By immersing the photographic plate to different depths in the liquid oxygen or air, the comparative opacities of the liquids could be observed. After exposure, the two plates were removed from the supports and developed together in the same solution, when similar results were obtained as in the previous experiments. The photographs have been examined by Captain Abney, who reports that the photographic action has been reduced by 80 per cent. at the temperature of 180°. If the photographic action is brought about by a chemical change, then it appears to be the only one that can be traced under such conditions, as substances having the most powerful affinities have no action on each other, and all voltaic combinations cease to give a current at such low temperatures. It is certain that the Eastman film, cooled to -200° by the evaporation of air in vacuo is still fairly sensitive to photographic action. Much further work, however, will be required to reach a definite conclusion as to what is taking place when substances sensitive to photographic action are subjected to such conditions of temperature. INDEX TO VOLUME XIV. ABEL, Sir Frederick, Donations, 383, Acting: an Art, 419. Actonian Prize (1893) awarded to Books of a Hundred Years Ago (no Air, Liquid, 1. Scientific Uses of, 393; Electrical Resistance of, at Low Aluminium as a Reducing Agent, 502. Annual Meeting (1893) 96, (1894) 280, Argon, 524; Spectrum of, 534; Density Armstrong, H. E., The Structure of Atmospheric Electricity, 460. - Pressure, Effect of Diminishing, Austin, A., Poetry and Pessimism (no BACON'S Key to Nature, 189. Beaufort, W. M., Donation, 383. Bidwell, S., Fogs, Clouds, and Light- Birr Castle Telescope and Apparatus, 629. Blyth, H. A., Donation, 150. Blyth, J., Donation, 150. FARRER, Sir Wm. J., Donation, 477. Fullerian Professor of Physiology GALTON, Sir Douglas, Donation, 378. Garson, J. G., Early British Races, 248. Graves, A. P., Old Irish Song, 169. Gravitation, Newtonian Constant of, Grubb, Sir Howard, The Development HANNAH, R., Donation, 150. Hodgkins, Thomas G., Portrait Pre- Hodgkins Trust, 40. Hopkinson, E., Electrical Railways, 50. Horse's Foot, Structure and Function Horsley, Victor, The Destructive Lubbock, Sir John, Speech on Dr. MAGNETIC condition of Matter at low Magnetisation of Iron, 539. McKendrick, J. G., The Theory of the Metals and their Alloys, 497. Electrical Resistance of, at Low Breaking Stress of, at Low Tem- Moissan's Researches on the Electric Moncrieff, Sir Colin Scott, The Nile, Mond, Ludwig, Proposal to Convey to Donations, 150, 388. (1893) February, 40; March, 63; (1894) February, 185; March, 203; (1895) February, 429; March, 477; April, 521; May, 564; June, 649; Moon, The Radiant Heat from the, 622. NATURE, Bacon's Key to, 189. Nervous Impulse, Transmission of, 94. Nichol, J. Bacon's Key to Nature, 189. Nitrogen, Weight of, 525. Noble, Sir Andrew, Donations, 139, Turacin, 44. Tyndall, J., Special Meeting on Occa- UNIT of Electrical Resistance, 604. VACUA, Production of High, 4, 396. WARD, H. Marshall, Action of Light Weldon, W. F. R., Fortuitous Variation Wigan, Mrs., Donation, 64. Wilson, R., Donation, 40. Woodhead, G. Sims, Antitoxic Serum YARROW, A. F., Donation, 108. END OF VOLUME XIV. LONDON: PRINTED BY WILLIAM CLOWES AND SONS, LIMITED, STAMFORD STREET AND CHARING CROSS. |