March 9, 1905] 



NA TURE 



455 



Chemical Society, February 15.— Prof. W. A. Tilden, 

 H-R.-S., president, in tiie chair. — Nitrogen lialogen deriva- 

 tives of the aliphatic diamines : F. D. Chattaway. The 

 compounds ethylenetetrachlorodiamine, ethyleneletrabromo- 

 diamine, and other similar bodies derived from diamines or 

 their diacyl derivatives were described. — The nitration of 

 substituted azophenols : J. T. Hewitt and V. H. Mitchell. 

 The authors have systematically studied the action of dilute 

 nitric acid and of a mi.xture of concentrated nitric and 

 sulphuric acids on the three nitrobenzeneazophenols. — The 

 estimation of saccharin : C. Proctor. The process described 

 by E. Emmet Reid for the estimation of saccharin has been 

 tested and found to be convenient and trustworthy. The paper 

 also described a simple volumetric process by means of 

 which the combined percentage of o-benzoicsulphinide and 

 /i-sulphamidobenzoic acid in commercial saccharin can be 

 determined. — The analysis of samples of milk referred to 

 the Government Laljoratory in connection with the Sale of 

 Food and Drugs .Acts : T. E. Thorpe. This paper contained 

 the results of an inquiry into the changes which occur in the 

 " souring " of milk, and especially as to the effects of these 

 on the usual analytical constants of milk. — The condensation 

 of anilinodiacetic esters in presence of sodium ethoxide : 

 .^. T. de Mouilpied. — The basic properties of oxygen at 

 low temperatures ; additive compounds of the halogens with 

 organic substances containing oxygen : D. Mcintosh, k 

 continuation of previous work on the combination of organic 

 compounds containing oxygen with the halogen hydrides to 

 form definite compounds. — Organic derivatives of silicon : F. 

 S. Kipping;. The preparation and reactions of a number of 

 these compounds were described. For the purpose of 

 svstematic nomenclature these compounds are regarded as 

 derivatives of silicane, SiH„ or of siliirol, SiH,.OH. — Photo- 

 graphic radiation of some mercury compounds : R. de J. F. 

 Struthers and J. E. Marsh. The mercurv compound 

 HgC,N,,2(NH,.NH.CeH,,) was found to act on a photo- 

 graphic plate through paper and aluminium foil, and slightly 

 through sheet zinc. Phenylhydrazine and a number of 

 mercurv salts were also found to exert a similar action. 



Royal Microscopical Society, February 15. — Dr. Dukin- 



field H. Scott, F.R.S., president, in the chair. — The Finlay- 

 son " comparascope " : Mr. Finlayson. The arrangement 

 exhibited provides a means of examining two slides simul- 

 taneously. — An optical bench for microscope illumination, 

 microphotography, micro-projection, lantern projection, &c., 

 and a large pliotomicrographic and enlarging camera, both 

 bench and camera being on rigid iron tables provided with 

 castors and fixing pedestals : C. Beck. — Practical micro- 

 metallography : J. E. Stead, F.R.S. Mr. Stead described 

 the machinery by means of which metals may be cut and 

 polished rapidly, and explained the various operations of 

 cutting, grinding, and polishing. Many specimens shown 

 by means of the epidiascope exhibited clearly the details 

 of the surface, and especially the coloration. The beautiful 

 colours produced by the heating process, by which some 

 portions became oxidized more quickly than others, were 

 very striking, especially in the case of a specimen of 

 a polished section of a meteorite, which almost equalled in 

 brilliancy and colour that well-known microscopic object the 

 wing of MorpJw mcuclaiis. 



Physical Society, February 24. — Prof. J. H. Poynling, 

 F.R.S., president, in the chair. — On the curvature method 

 of teaching geometrical optics : Dr. C. V. Orysdale. The 

 paper has been undertaken with the two-fold object of giving 

 a systematic exposition of the method of teaching elementary 

 optics which the author has found most suitable, and of 

 giving an introduction to a subsequent paper on the treat- 

 ment of aberrations by curvature methods. — Dr. Meisling's 

 colour-patch apparatus : R. J. Sovvter. The apparatus is 

 simple in its principle and construction, and is specially 

 adapted for testing colour-blindness. — A method of illus- 

 trating the laws of the simple pendulum : J. Schofield. 

 A pendulum is fitted at its lower end with a narrow hori- 

 zontal framework carrying vertical transverse wires. During 

 the oscillations of the pendulum these wires are caused to 

 cut a jet of mercury, and time signals are sent to the re- 

 cording mechanism of a chronograph. The distances 

 between the wires are known, and together with the time- 

 measures they yield a displacement-time curve of the motion. 

 From this the kinematical curves and equations of the 



NO. 1S45, VOL. 71] 



moving system may be deduced by the usual methods. In 

 the actual apparatus a tuning-fork arrangement with an 

 accuracy of about i 200 of a second is used as the chrono- 

 graph, and the results obtained from the pendulum are 

 accurate to about three per cent. The principle has also been 

 applied to torsion pendulums.— String models of optical 

 systems: J. Schofield. In these models the lenses and 

 prisms are made of celluloid, so that the paths of rays 

 through them can be shown. 



Paris. 

 Academy ol Sciences, February 27.— M. Troost in the 

 chair. — The precautions necessary in the mode of execution 

 of certain researches requiring high precision : M. Lcewy. 

 A lengthened study as to the cause of some systematic errors 

 m the circle of a meridian instrument, wrongly attributed 

 to flexure of the circles, showed that these effects were due 

 to bad definition of the images of the lines, and could be 

 remedied by increasing the definition of the reading micro- 

 scopes and improving the lighting. In the determination 

 of the constant of aberration, and of refraction, by means 

 of a double mirror cut out of one block of glass, a deforma- 

 tion of the image was observed which rendered accurate 

 readings difficult. The form to be given to the two re- 

 flecting surfaces to get regular stellar images has been 

 worked out. — On the observation of the partial eclipse of the 

 moon of February 19 : M. Puiseux. The twelve photo- 

 graphs taken are discussed in detail, and in some respects 

 are not in agreement with descriptions given before 1866. 

 Recent observations render improbable any new changes in 

 the moon's crust. — On an application of the iris diaphragm 

 in astronomy ; -M. Salet. An iris diaphragm, introduced 

 into the plane of the micrometer wires of an eyepiece, has 

 the effect of suppressing diffused light, and thus facilitating 

 observations on faint objects. — Families of Lamy with plane 



orthogonal trajectories : G. Carrus On algebraic surfaces : 



Federigo Enriques. — On functions with an infinity of vari- 

 ables : Maurice Frechet. — On some theorems of Riemann : 

 P. Fatou. — The theory of the limiting trajectory of an 

 aeroplane : Marcel Brillouin. — On the intensity of photo- 

 graphic impressions produced by feeble illuminations : C. 

 Gutton. It is shown experimentally that in a photographic 

 negative the contrasts are exaggerated in the faintly illu- 

 minated regions and attenuated in the more stronglv lighted 

 parts. On a positive, on the contrary, the differences of 

 lighting are faithfully reproduced. — On the kathode rays 

 emitted by the anode : E. Rogovsky. — The surface tension 

 of a dielectric in the electric field : Ch. Fortin. In an 

 electric field of 20,000 volts per centimetre, normal to the 

 surface, the relative variation of the surface tension of the 

 petroleum, if it exists, is less than i /450th. If the variation 

 of the surface tension with the strength of the field be 

 regarded as negligible, the arrangement of apparatus 

 described serves as a new method of measuring the specific 

 inductive capacity of the liquid. — On the spectra of the 

 fluorides of the alkaline earths in the electric arc : Ch. 

 Fabry. — On the ionisation due to the radium emanation : 

 William Duane. — On the purification of gadolina and on 

 the atomic weight of gadolinium : G. Urbain. The method 

 of purification adopted was the fractional crystallisation of 

 the double nitrate of gadolinium and nickel from nitric acid 

 of densitv 1.3. The purity of the product was established 

 by the constancy of the ratio between the crystallised sulphate 

 and the oxide, and the mean atomic weight is given as 

 157.23 (0 = 16). The spark spectrum of this product is being 

 specially studied by .Sir William Crookes, and the arc 

 spectrum by Dr. Eberhard, who will publish their results 

 shortly. — On some osmionitrites and on a nitrite of 

 osmium : L. Wintrebert. — A special constituent obtained 

 in the tempering of an aluminium bronze : Pierre Breuil. — 

 On /3-decahydronaphthol and the octahydride of naphthalene : 

 Henri Leroux. i3-naphthol, reduced by means of the 

 Sabatier and Senderens reaction, gives rise to several sub- 

 stances, from which the decahydride was separated in the 

 pure state. That it is an alcohol was clearly shown by the 

 preparation of the acetate and the phenylurethane, and 

 also by its dehydration to naphthalene octahydride by potass- 

 ium bisulphate. — On the glycol of anethol : E. Varenne 

 and L. Godefroy. — The characters of the polygastric 

 muscles : J. Chaine. — On the salivary, cephalic and meta- 

 thoracic glands of some Hemiptera : L. Bordas. — The 



