November 19, 1908J 



NA TURE 



opaque variety by burnishing, as in writing on the surface 

 of the glass with an agate stylo. The change does not 

 take place if silver-leaf be heated in vacuo, but it occurs 

 readily with one-fiftieth of an atmosphere of oxygen. The 

 silver does not increase in weight or the oxygen alter 

 in volume, though o.xygen appears to be necessary in order 

 to produce the change. It is suggested that an oxide of 

 silver may be momentarily formed and again decomposed 

 by heat in the presence of more oxygen. The thinnest 

 rolled metal obtainable, about i /3000th of an inch thick, 

 does not become transparent. Intermediate thicknesses 

 have yet to be examined. 



Thin sheet copper, about i/75,oooth of an inch in thick- 

 ness, remains opaque when heated in a reducing atmo- 

 sphere. In air or oxygen, however, it becomes transparent 

 if heated for a suitable time at temperatures between 

 about 200° and 400° C. At the lower temperatures the 

 transparency is very marked, and the light transmitted is a 

 brilliant emerald-green. As the temperature rises further 

 oxidation takes place, and the colour gradually passes 

 through olive and dark red to black. If the light-green 

 transparent metal be treated with a diluted acid, metallic 

 copper with a brilliant metallic lustre is obtained, while 

 the green transparency disappears. The effect is due to 

 oxidation, as the copper absorbs oxygen continuously 

 during the heating. 



Aluminium and Dutch metal do not appear to become 

 transparent, nor have transparent films yet been obtained 

 from sulphides. It is suggested that transparent films 

 such as have now been obtained from copper are formed 

 in all cases where a succession of spectrum colours are 

 obtained on heating a metal in air. 



Royal Microscopical Society, October 21. — Dr. J. W. H. 

 Eyre, vice-president, in the chair.- — The mouth-parts of the 

 Nemocera, and their relation to the other families in 

 Diptera — with corrections and additions to the paper pub- 

 lished in 1904 : W. Wesche. — (i) The resolution of 

 periodic structures ; (2) an auxiliary illuminating lens : 

 E. M. Nelson. — Micrococcus melitensis : A. A. C. E. 

 Merlin and E. M. Nelson. 



Physical Society, October 23. — The meeting was held at 

 the National Physical Laboratory, Bushy House, Tedding- 

 ton, by invitation of the director. All departments of the 

 laboratory were thrown open for inspection, and, in 

 addition, a number of special demonstrations were 

 arranged. 



Society of Chemical Industry, November 2. — Dr. 

 Lewkowitsch in the chair. — Chemical industry in relation 

 to agriculture : Prof. A. Frank. After referring to the 

 great services of Liebig to agriculture, the author gave an 

 historical survey of the manufacture and agricultural 

 uses of, phosphates, and the production of potash. 

 Ammonium sulphate, Chile saltpetre, and the utilisation of 

 atmospheric nitrogen were also discussed, and an account 

 was given of the author's own work in effecting the com- 

 bination of atmospheric nitrogen with carbides ol the 

 alkalis and the alkaline earths. By decomposing the 

 calcium cyanamide with water under high pressure 

 ammonium salts are formed. Possibilities of calcium 

 cyanamide as a fertiliser are dealt with, and some statistics 

 relating to the output of calcium carbide are included. 

 The work of Mond on the simultaneous production of 

 power gas has made it possible to utilise the large stores 

 of energy accumulated in bog areas in the form of peat. 

 The author and Caro, with the assistance of Mond, have 

 been able to gasify peat containing 50 per cent, to 55 per 

 cent, of water without difficulty. 



Zoological Society, November ^. — Mr. Frederick Gillett, 

 vice-president, in the chair. — Mammals from Inkerman, 

 near Townsville, North Queensland, collected by Mr. W. 

 Stalker and presented to the National Museum by Sir 

 William Ingram, Bart., and the Hon. John Forrest : 

 Oldfield Thomas and Guy Dollman. The collection 

 showed clearly that the Townsville region belonged 

 faunistically to North .Australia, the species beiug nearly 

 identical with those of New South Wales and Victoria. 

 Several species and subspecies were described as new. — 

 (i) Takins from Sze-chuen and Bhutan ; (2) .^n Indian 

 dolphin and porpoise : R. Lydekker. 



XO. 20,^8, VOL. 79] 



Paris. 

 Academy of Sciences, November 9. — M. Bouchard in the 

 chair. — The pi-esident announced to the academy the death 

 of M. A. Ditte. — The products of the reaction of sodium 

 amide on ketones : A. Halier and Ed. Bauer. Benzo- 

 phenone, treated in benzene or toluene solution with 

 sodium amide, if the materials are perfectly free from 

 moisture, gives the compound CjHjC(ONa)(CjH5)(NH,), 

 and this on treatment with water regenerates the benzo- 

 phenone, together with ammonia and caustic soda. In 

 presence of a trace of water a different reaction takes 

 place, and the addition of water to the reaction product 

 gives benzene, benzamide, and caustic soda. This reaction 

 appears to be general with the aromatic ketones, anthra- 

 quinone being an exception. — The mode of formation of 

 the Puy de Dome and the rocks which constitute it : A. 

 Lacroix. A detailed examination of the structure of the 

 Puy de Dome shows that it is comparable, not with Mt. 

 Pelfe, but with Guadeloupe. Each of the domes, forming 

 the chain of the Puys, has a distinct history requiring 

 separate examination. — M. Henneguy was elected a 

 member of the section of anatomy and zoology in the 

 place of the late M. A. Giard. — Physical observations of 

 the comet 1908c, made at the Observatory of Lyons : J. 

 Guillaume. A detailed account of the numerous changes 

 in the appearance of the nucleus and tail of this comet 

 observed between September 5 and October 20. — The use 

 of compasses of great magnetic moment : Louis Dunoyer. 

 A discussion of the theory of the correction of compasses 

 of great magnetic moment (2000 to 5000 C.G.S. units). 

 The formula developed have been submitted to an experi- 

 mental control. — The geometrical applications of certain 

 remarkable movements : J. Haag;. — The formation of 

 centres of gyration behind an obstacle in motion : Henri 

 Benard. The vortices produced behind a cylinder moving 

 in a liquid with a uniform velocity were studied by means 

 of kinematographic methods. The vortices were spaced 

 at equal distances behind the moving body, this equi- 

 distance being found to be independent of the velocity, but 

 increasing in the same direction as the viscosity of the 

 liquid. — The ionisation of phosphorus and phosphorescence : 

 L^on and Eugene Bloch. Experiments are described 

 proving that phosphorescence, ionisation, and ozone are 

 all produced in the same region. This region can be 

 completely separated from the phosphorus if the velocity 

 of the air current is increased above a certain limit, and 

 it is possible to separate this region several metres from 

 the phosphorus. These facts indicate that the phosphor- 

 escence, ionisation, and the ozone are not produced by the 

 direct oxidation of the solid phosphorus, but by the oxida- 

 tion of a substance emanating from the phosphorus and 

 carried off by the gaseous current. This substance is 

 most probably phosphorus anhydride. — The radio-activity 

 of the gases from the thermal water of Uriage (Isfere) : G. 

 Massol. The gases escaping from the water have a 

 radio-activity only one-fourth of that of the gases remain- 

 ing dissolved in the water. This emanation evaporates at 

 the same time as the water ; the saline residue from a 

 half-litre of the water evaporated on the water bath was 

 completely inactive. — The polarisation of the living man 

 submitted to the action of the continuous current : M. 

 Chanoz. — The radio-activity of the waters of Uriage-les- 

 Bains (Is^re) ; Paul Besson. — Contribution to the study 

 of lenses : C. Maltezos. — A monotelephone with a note 

 capable of regulation : .'\. Biondel. The apparatus is less 

 sensitive than that recently described by M. Abraham, 

 but possesses the advantage of being less easily broken. 

 — The reaction of the ether on matter as the cause of 

 universal attraction : O. Keller. — The true atomic weight 

 of silver according to the experiments of Stas : Louis 

 Dubreuii. The author has applied the method developed 

 hv him in a previous paper to the experiments of Stas on 

 the atomic w^eight of silver. The general mean arrived at 

 is 107-9921, or practically 108. — The alloys of silicon and 

 silver : G. Arrivaut. The current views regarding the 

 existence of a silicide of silver are divergent, Wohler, 

 Warren, and Chalmot regarding the existence as proved, 

 Percy, Moissan, and Vigouroux holding the opposite 

 opinion. The author has determined the melting points 

 both of the first crystallisation and the eutectic of a series 

 of mixtures of silver and silicon. The results do not sup- 



