absolute alcohol, the metal dissolves, possibly as an acid hyposulphite. This solution, left in a vacuum, deposits magnesium acid: hyposulphite.-On acetyl-lactic V. Auger. Previous accounts of this substance being contradictory, the author has attempted to procure it in a pure state. It can be obtained either by the action of acetyl chloride on calcium lactate or on lactic acid, or by using acetic anhydride in the place of the acetyl chloride. The substance was obtained in a crystalline form in all three preparations, and its physical and chemical properties are given.-On the compounds of aluminium chloride with hydrocarbons and hydrogen chloride: G. Gustavson. By the interaction of benzene, isopropyl chloride, and aluminium chloride, the author has isolated a definite compound, the action of which, in the Friedel and Crafts reaction, may be compared to that of a ferment. This substance can unite both with hydrocarbons and hydrogen chloride.--On the hydrides of phenanthrene: Pierre Breteau. Previous work on the hydrogen addition compounds of phenanthrene has been carried out with the aid of hydriodic acid. The author has applied the Sabatier and Senderens reaction with reduced nickel, and in the present communication gives the results obtained with the hexahydride and octahydride of phenanthrene. On the retrogradation of artificial starch: E. Roux.-The influence of the ethylene function in an active molecule J. Minguin. With the view of throwing further light on the effect of the ethylene linkage on the rotation, the author has prepared amyl succinate, maleate, and fumarate, as well as the corresponding esters of bornyl alcohol, and has measured the rotatory power.-The constitution of the ligamentary ridge and the evolution of the ligament in existing Acephale analogous to the Rudisteæ: R. Anthony.-Diagrams showing the ligament in section are given for Unio Pictorum and Aetheria Caillaudi at two ages.-Heterotypical mitosis in the Ascomycetes: René Maire.On the possible rôle of slipping in metallogeny: L. De Launay. An application of the idea of charriage to a study of the continuity of metallic lodes.-On the existence of schists with graptoliths at Haci-El-Khenig, Central Sahara G. B. M. Flamand. Specimens of schists bearing fossils, collected by Captain Cottenest, prove to be characteristically Silurian, and form the first definite proof of this system in the Central Sahara.-On the presence of the Middle and Upper Carboniferous in the Sahara: Enile Haug. On an extraordinary halo observed at Paris: Louis Besson. This halo, which was observed at the Montsouris Observatory on March 26, besides the ordinary circle and parhelia of 22°, presented two abnormal coloured arcs, the angular measurements of which are given. DIARY OF SOCIETIES. ROYAL SOCIETY, at 4.30.-On a New Type of Electric Furnace; with a ROYAL INSTITUTION, at 5.-Synthetic Chemistry: Prof. R. Meldola, F.R.S. INSTITUTION OF ELECTRICAL ENGINEERS, at 8.-The Alternating Current Series Motor: F. Creedy.-Discussion of Mr. Bion J. Arnold's address to the joint meeting at St. Louis. INSTITUTION OF MINING AND METALLURGY, at 8.-The Kedabeg Copper Mines: Gustav Köller-Refining Gold Bullion and Cyanide Precipitates with Oxygen Gas: T. Kirke Rose.-Wood Gas for Power Purposes and Gas Generator: G. M. Douglas.--Notes on the Prestea District, Gold Coast Colony: P. Poore.-Notes on the New Dharwar Gold Field of India: R. O. Ahlers.-The Cause of Border Segregation in some Igneous Magmas: J. Park. MATHEMATICAL SOCIETY, at 5.30.-On Irreducible Jacobians of Degree Six P. W. Wood-On Fermat's Numbers and the Converse of Fermat's Theorem: A E. Western.-On the Strains that accompany Bending: Prof. A. E. H. Love. -Ordinary Inner Limiting Sets in the Plane or Higher Space: Dr. W. H. Young. FRIDAY, APRIL 14. ROYAL INSTITUTION, at 9.-The Law of Pressure of Gases below Atmosphere: Lord Rayleigh. PHYSICAL SOCIETY, at 8.-On Ellipsoidal Lenses: R. J. Sowter. -(1) The Determination of the Moment of Inertia of the Magnets used in the Measurement of the Horizontal Component of the Earth's Field : (+) Exhibition of a Series of Lecture Experiments illustrating the Proper ties of the Gaseous Ions produced by Radium and other Sources: Dr. W. Watson, F.R.S. ROYAL ASTRONOMICAL SOCIETY, at 5.-Value of Meteoric Radians Based on Three Paths: W. F. Denning.-Determination of Longitude m the Planet Jupiter G. W. Hough.-(1) Revised Elements of UY Cygri: (2) Revised Elements of Y Lyræ: A. Stanley Williams.-Further Nate on Instrumental Errors affecting Observations of the Moon; in reply to Mr. Cowell's paper of June, 1904: H. H. Turner. -Reply to Prof Turner's paper: P. H. Cowell.-Note on the Point Distributions on a Sphere; with Remarks on the Determination of the Apex of the Sun's Motion: H. C. Plummer. MALACOLOGICAL SOCIETY, at 8.-Anatomical and Systematic Notes an Dorcasia, Trigonephros, Corilla, Thersites, and Chloritis: Henry A. Pilsbry. Some Account of the Anatomy of Cassidaria rugosa, LAlexander Reynell.-Notes on a small Collection of Shells from the Victoria Falls, Zambesi River: H. B. Preston -Descriptions of Siz New Species of Land Shells from South Africa: H. Burnup. INSTITUTION OF MECHANICAL ENGINEERS, at 8.-President's Address, Conclusion of discussion on Steam-engine Research Report and Prof. Capper's reply. SATURDAY, APRIL 15. ROVAL INSTITUTION, at 3.-Sone Controverted Questions of Optics: INSTITUTE OF ACTUARIES, at 5.-On the Importance and Practicabuty TUESDAY, APRIL 18. WEDNESDAY, APRIL 10. GEOLOGICAL SOCIETY, at 8.-The Blea Wyke Rocks and the Dogger in North-East Yorkshire: R. H. 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