nary temperature. The first plan (Fig. 2) was simply to immerse a strip of sensitive bromide paper A B, in one of the vacuum vessels containing liquid oxygen, and when the part immersed had been thoroughly cooled down, exposing it to the light of a piece of burning magnesium. The paper was then developed, when a result something resembling C was obtained. The part which had been cooled by the liquid oxygen, as at A, was untouched by the light, whereas the portion of paper above the liquid at B developed up quite black. Further modifications were made in Fig. 3, where the strip of sensitive film E was enclosed in a cover of sheet lead B, having two small discs cut away as at C and D. The strip was then cooled in liquid oxygen A, and then exposed to a flash of burning magnesium. After development, the strip appeared something like E, when again the action of the light was considerably diminished on the part of the film which had been cooled. In Fig. 4 a form of apparatus was adopted whereby the exposures were made without the disadvantago of the light passing through the glass sides of the vacuum vessels. B and E were vacuum vessels enclosed in a blackened box; into B a quantity of liquid oxygen was poured. The sensitive plate or film was then lowered so as just to touch the surface of the liquid as at C. D was a comparison plate exposed at the same time and at the same distance from the source of light A, only the comparison plate 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. 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 Annual Meeting (1893) 96, (1894) 280, Argon, 524; Spectrum of, 534; Density Armstrong, H. E., The Structure of Atmospheric Electricity, 460. 456. Pressure, Effect of Diminishing, Austin, A., Poetry and Pessimism (no BACON'S Key to Nature, 189. Beaufort, W. M., Donation, 383. Bert, M. Paul, Researches on Atmos- 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 Trish Song, 169. Gravitation, Newtonian Constant of, Grubb, Sir Howard, The Development HANNAH, R., Donation, 150. Hodgkins, Thomas G., Portrait Pre- Hopkinson, E., Electrical Railways, 50. Horse's Foot, Structure and Function Horsley, Victor, The Effects of Projectiles, 228. 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; 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, |