illumination with that of the standard light. Experiment had shown that the sensitiveness of the instrument is greatest when the difference of the contrasted illuminations is 3 per cent., and amounts then to per cent. He further gave an account of experiments which he and Dr. Lummer had made on the utilization of glow-lamps as standards of comparison. When fed by accumulators these lamps yield a light which only varies by I per cent. during a period of 200 hours provided the E. M. F. of the accumulators is kept constant. The authors are now busy with the endeavour to construct a standard glow-lamp for comparison with unknown sources of light. Dr. Lummer demonstrated Abbé's apparatus for testing transparent films with planeparallel surfaces. After briefly describing the interference phenomena produced by thick plane-parallel glass plates, he explained how Tizeau's bands and Newton's rings are employed for testing the plates, using monochromatic sodium-light. The light passes through a reflecting prism and through a lens, and then falls on the plate, from which it is reflected and passes back by the same path to the eye, being now passed through a second lens by means of which the bands or rings may be seen. The occurrence of interference-bands is entirely dependent upon the thickness of the plate: if this is absolutely uniformly thick throughout, the interference phenomena show no change if the plate is moved from side to side in its own plane, and by so doing the parallelism of its sides may be rapidly tested.

proves that in this instance no glucose whatever is formed, as was lately believed to be the case. The development of luminosity is constantly accompanied by the transition of peptones into organized, living matter, under the influence of free oxygen, with or without the concurrence of another carbonic combination.

BOOKS, PAMPHLETS, and SERIALS RECEIVED.

Among the Selkirk Glaciers: W. S. Green (Macmillan).-Flora Tangutica. fasc. i.: C. J. Maximowicz (Petropoli)-Enumeratio Plantarum Huiusque in Mongolia, fasc. i.: C. J. Maximowicz (Petropoli).-The Human Egu Canto i.: J. F. Rowbotham (K. Paul).-Agende de Chimiste, Salet, Girard and Pabst (Hachette).-1 he Theory of Determinants in the Historical Order of its Development; Part i., Determinants in General: T. Muir (Macmillan) -The Microtomist's Vade- Mecum, 2nd Edition: A. B. Lee (Churchill) Guide Pratique de L'Amateur Électricien: E. Keignart (Paris, Michele')— Musiconomia o Leggi Fondamentali della Scienza Musicale: P. Crotti (Parma, Battei) L'Éclairage Électrique Actuel, 2nd Edition: J. Couture (Paris, Michelet) -Das Reizleitende Gewebesystem der Sinnpflanze : Dr. G Haberlandt (Leipzig. Engelmann).-Traité Ency. de Photographie, 15 Mars C. Fabre (Paris, Gauthier-Villars).-Proceedings of the Aristotelian Society, vol. i. No. 3, Part 1 (Williams and Norgate).-Mind, April (Williams and Norgate).-Geological Magazine, April (K. Paul).-Quarterly Journal of Microscopical Science, April (Churchill).-Journal of the Royal Agricultural Society of England, 3rd Series, Part 1 (Murray),—Journal of the Royal Horticultural Society, vol. xii. Part 1 (London).

Ce, La, Di: oxalic acid, ferrocyamide of potassium.

Zn, Cn, Co: sulphocyanide of mercury and ammonium.

Co, Ni: nitrite of potassium and acetate of lead.

Pb, Bi, Fe: bichromate of potassium and potash.

Bi, Sb, Sn: oxalic acid, chloride of rubidium.

Sb, Sn, Ti: chloride of barium and oxalic acid. Details will soon be published, when the necessary finish has been given to the methods for separation, hitherto somewhat neglected.-M. Martin read a paper on the geology of the Kei Islands, and, in connection therewith, on the Australian-Asiatic boundary line. In accordance with the fact that in Great Kei we meet with nothing but a Tertiary formation, and that the nature of the rocks of Great Kei agrees with that of the coast of New Guinea, M. Martin inferred that this boundary line must be drawn geognostically, to the west of Great Kei and to the north-west of Timor.-Dr. Beyerinck treated of the luminous food and the plastic food of phosphorescent Bacteria. Of the six species of phosphorescent Bacteria hitherto known, four-viz. the alimental gelatine non-melting Bacterium phosphorescens and B. Pflügeri of luminous fish, and the Baltic phosphorescent Bacteria, B. Fischeri and B. balticum, require, besides peptone, a second carbonic combination, as glycerine, glucose, or asparagine, for their complete nourishment, i.c. to "phosphoresce' and grow. They may be called peptone-carbon-bacteria. The gelatine quick-melting phosphorescent bacteria from the West Indian Sea and the North Sea, B. indicum and B. luminosum, can phosphoresce and grow on peptone alone. They are, therefore, peptone-bacteria. Again, other bacteria can derive their nitrogen either from amids, the amid-bacteria, or from ammoniac, the ammoniac-bacteria. Also moulds, yeasts, and Protozoa may be classed in this system. The Bacterium Pflügeri does emit light with peptone and glucose, but not with peptone and maltose, while the Bacterium phosphorescens emits light both with glucose and maltose. Now if we mix some starch in a phosphorescens-peptone-gelatine, obtained by mixing this gelatine with a very great number of B. phosphorescens, and place upon this some ptyaline, pancreas-diastase, or urindiastase (nefrozymase), fields of light make their appearance; if, however, we placed these same sorts of diastase on a Pflügeri-peptonestarch-gelatine, then no fields of light would appear, which

some

Letters to the Editor:

Hicks:

Elementary Dynamics of Particles and Solids."-G. A. B..

533

334

GEOLOGICAL SOCIETY, at 8.-Notes on some of the Palæozoic Rocks of North-Western Germany: Prof. A. von Konen. Communicated by Sir Warington W. Smyth, F. R.S.-On the Origin of the Basins of the Great American Lakes: Dr. J. W. Spencer -On Ornithosaur.an Remains from the Oxford Clay of Northampton: R. Lydekker.-On Certain Physical Phenomena exhibited by the so-called "Raised Beaches" of Hope's Nose and the Thatcher Rock, Devon: D. Pidgeon.-Notes on a "Wash-out"* found in the Pleasley and Teversall Collieries, Derbyshire and Nottinghamshire: J. C. B. Hendy. Communicated by Dr. W. T. Blanford, F.R.S.

ROYAL METEOROLOGICAL SOCIETY, at 7-The Cold Period at the Beginning of March 1890: Charles Harding. -Note on the Whirlwind which occurred at Fulford, near York, March 8, 1890: J. E. Clark.-On the Possibility of Forecasting the Weather by means of Monthly Averages: Albert E. Watson.-Rainfall of the Globe: W. B. Tripp. ROYAL MICROSCOPICAL SOCIETY, at 8.-Fresh-water Algae of North Wales: W. West.-The State in which Water exists in Live Protoplasm: M. M. Hartog.

SOCIETY OF ARTS, at 8.

THURSDAY, APRIL 17. ROVAL SOCIETY, at 4.30.-The following papers will probably be read:Preliminary Note on Supplementary Magnetic Surveys of Special Districts in the British Isles: Profs. Rücker and Thorpe, F.R.S.-Notes on some Peculiar Relations which appear in the Great Pyramid from the Precise Measures of Mr. Flinders Petrie: Captain Downing, R.A.-The Variations occurring in certain Decapod Crustacea; I. Crangon vulgaris : W. F. R. Weldon.-Observations on the Anatomy and Development of Apteryx Prof. T. Jeffery Parker. F. R.S.

CHEMICAL SOCIETY, at 8.-Phosphorous Oxide: Prof. T. E. Thorpe, F.R.S, and T. E. Tutton.

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LEEDS MECHANICS' INSTITUTION AND LITERARY SOCIETY.

The Directors invite applications for the post of HEAD MASTER of the SCHOOL OF SCIENCE AND TECHNOLOGY and TEACHER OF CHEMISTRY to the Boys' and Girls' Schools in connection with the Institution, the present Head Master having been elected to the Head Master. ship of the Merchant Venturers' School, Bristol. The Master appointed will be expected to take the classes in Theoretical and Practical Inorganic and Organic Chemistry, and to exercise a general supervision over the other classes of the School of Science. The School buildings are new, and furnished with all necessary materials and apparatus for science teaching. Salary, partly fixed and partly dependent upon results, amounts to about £280. Full particulars may be had from the SECRETARY, to whom applications must be sent not later than April 23.

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The Classes re-commence on MAY 1, and are so arranged as to afford a convenient opportunity for Students to commence their Medical Course Full information may be obtained from the Office of the College, Gover Street, W.C.

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