January 12, 1899] 



NATURE 



263 



J. Fillischer, Swift and Son, ami Watson and Sons. — Among 

 the other objects exhibited may be mentioned typical species of 

 Foraminifera selected from various localities by Mr. A. Earland, 

 which were rare and beautiful ; and mounted specimens of 

 Hydrozoa, by Mr. G. E. Harris. 



Edinburgh. 



Royal Society, December ig. — Lord Kelvin in the chair. — 

 Mr. R. C;. .\lford read a paper on crane scaffoldings, their 

 mathematical calculations and probable theoretical deficiencies. 

 The paper was a comparison of two similar scaflfoldings, one of 

 which was overturned in a gale which the other resisted. — 

 In a note on dew bows, Drs. Knott and Lundie gave an 

 account of a system of brilliant "bows" produced at night 

 on the ground, the source of light being the gas-lamp or 

 electric light of the street. The phenomenon required the 

 existence on the ground of a layer of numerous globules of 

 water of nearly the same size and so small as to suffer little 

 distortion from perfect sphericity. The globules were fog 

 particles, which had gradually settled down in the still air of the 

 last of four days of heavy fog. The curves formed by these 

 dew bows are plane sections of a toroidal surface. Some of the 

 curves were drawn on a black board by means of a simple but 

 obvious kinematical model. — Lord Kelvin communicated a paper 

 on the reflection and refraction of solitary plane waves at a plane 

 interface between two isolropic elastic mediums, fluid, solid, or 

 ether. The investigation presented certain novelties of treat- 

 ment. One of these was the introduction of the condensational- 

 rarefactional waves of reflection and refraction moving with 

 slow velocities through the (contractile) ethers. (The four 

 waves into which a wave of either type breaks up at the boundary 

 of two elastic solids were first discussed by Knott in 1888, with 

 special reference to earthquake waves.) Then there was the 

 question of the total reflection of a solitary wave instead of a 

 train of waves. And finally there was the application of the 

 principle of the continuity of the rotational magnetic force at the 

 interface. Fresnel's sine and tangent formula for the reflection 

 of plane polarised rays followed at once. — Mr. Sydney A. Kay 

 communicated a paper on the equilibrium between sulphuric acids 

 and sulphates in aqueous solutions. The concentrations of the 

 free acid, neutral sulphate, and acid sulphate in solutions con- 

 taining sulphuric acid and a neutral sulphate were determined by 

 means of a reaction velocity method — namely, by the catalysis 

 of ethylic acetate. Then the degrees of dissociation in the 

 three substances were calculated from Kohlrausch's later deter- 

 minations of the electric conductivities at infinite dilution. 

 Finally an expression for the equilibrium was developed as an 

 empirical formula which, within the limits of the experiments, 

 gave results in close agreement with observation. The formula 

 was 



{ Cone. HaSOtCi- a,)}''"^ ^ A 



Cone. MHS04(I - 03) [Cone. MjSOiCl - a^Y 



where cone, means concentration, M is the symbol for the metal 

 involved, aj a.> 03 are the degrees of dissociation, A and x are 

 constants with characteristic values for each case. Thus, when 

 M is potassium, sodium or lithium, A has corresponding values 

 o'259, o'o6i8, or o'o6oo respectively, and JT has values I, i'35i 

 I "35 respectively. — Mr. David Robertson read a paper on dust 

 figures of electrostatic lines of force. These were obtained by 

 sprinkling the dust over a glass plate against the under surface 

 of which were pressed electrodes in connection with a Wims- 

 hurst machine. The chief difficulty was to get a suitable sub- 

 stance ; for the particles should be sufficiently conducting to be 

 acted on inductively, and yet sufficiently insulating to prevent 

 esc.ipe of the charges. Of the many kinds of dust tried, pure 

 mahogany sawdust coloured with ink was found to be the most 

 efiicient. It was stated that the secret of getting good results 

 lay in stopping the action of the machine at the right moment. 

 Many interesting examples of the curves were exhibited. — In a 

 note on the action of persulpates on iodine, Dr. Hugh Marshall 

 drew attention to a reaction which seems to have been neglected 

 by recent experimenters. When, for example, a solution of 

 potassium iodide is being boiled with ammonium persulphate so 

 as to decompose it and drive oft' the iodine by sublimation, the 

 iodine in the liquid seems to disappear at a more rapid rate than 

 corresponds to the amount volatilised. In fact, as was proved 

 by direct experiment, the iodine is oxidised by the per.sulphate, 

 and becomes iodic acid. — A paper by Prof. Anglin, on the 



NO. 1524, VOL. 59] 



■summation of the series whose //Ih terms are «„ and i/k„ where 



II „ denotes 



{an + b) \a{n -f l) + l>\ \a{n + 2) + 'j\ . . . [a{n + r - I) + 6\ 



was also read. 



Paris. 



Academy of Sciences, January 2» — M. van Tieghem in 

 the chair. — On the estimation of phosphorus and sulphur in 

 plants and their ashes, by M. Berthelot. Of the various 

 methods suggested for determining sulphur and phosphorus in 

 plants, burning in a stream of oxygen, and subsequently passing 

 the gases over a long column of red-hot sodium carbonate, gave 

 the highest results. ' Prolonged boiling with strong nitric acid or 

 estimation after incineration showed large deficiencies in both 

 sulphur and phosphorus.— On the presence and estimation of 

 chlorine in plants, by M. Berthelot. Combustion with oxygen 

 in presence of sodium carbonate gave higher results than a 

 careful incineration in the ordinary way. An attempt was 

 made to distinguish between the total chlorine and the chlorine 

 existing in the plant in the form of chlorides, but without much 

 success. — Preparation and properties of an organic ammonium, 

 lithium— monomethylammonium, by M. Henri Moissan. 

 Anhydrous methylamine reacts vigorously with lithium at 

 temperatures near o°C. , forming a blue solution similar to the 

 alkaline ammoniums. The composition approximated to Li 

 (CH3.NH,). In a vacuum this loses methylamine, and finally 

 deposits brilliant crystals of metallic lithium, no gas being 

 evolved. — Influences of metallic armatures upon the properties 

 of mortars, by M. Considere. — Constitution of the ring of small 

 planets, by M. Jean Mascart. Curves are given showing the dis- 

 tribution of longitudes of the nodes and perihelia of the asteroids 

 for every 30°. — Observation of the total eclipse of the moon of 

 December 27, 1S98, made at the Observatory of Lyons, by 

 M. Ch. Andre. The .state of the sky interfered considerably 

 with the observations. — Observations made at the Observatory 

 of Toulouse during the eclipse of December 27, 1898, by 

 MM. Baillaud, Bourget, Montangerand, Rossard, and Besson, 

 by M. Baillaud. Ten photographs were successfully taken during 

 the eclipse — Observations of the Brooks comet (October 1898) 

 and Chase comet, made at the Observatory of Toulouse 

 with the Brunner equatorial, by M. F Rossard.— On 

 the propagation of liquid waves through water, by M. 

 Georges Poisson.— On the absorption of light by a body 

 placed in a magnetic field, by M. Auguste Righi. Wheii such 

 gases as nitrogen peroxide, iodine, iodine monobromide, iodine 

 monochloride, or selenium tetrabromide of suitable concentra- 

 tion are placed in the path of a ray of light in a strong m.-ignetic 

 field, a distinct change in the colour of the transmitted light is 

 noticeable when the electromagnetic circuit is completed. — On 

 a simple form of magnetometer, by M. A. Guillet. Tvvo 

 diagrams of the apparatus are given, together with the theory 

 of the instrument, but no actu.il measurements are cited. — 

 General method of separation of chlorine, bromine and iodine 

 in the form of silver salts, by M. H. Baubigny. The dry silver 

 salts are treated with sulphuric acid containing bichromate, the 

 chlorine and bromine distilled off into potash containing 

 sulphite, and these separated by the use of potassium perman- 

 ganate and copper sulphate. The two test analyses given are 

 very satisfactory. — On the formation of the head of the 

 Hymenoptera, by M. L. G. Seurat. The head is formed 

 uniquely from the head of the larva ; at first invaginated, this 

 head, by a movement of rotation in the median plane, becomes 

 devaginated and acquires its final form. —A transverse section 

 of the Brian9on Alps, froin Gironde to the Italian frontier, by 

 MM. Kilian and Lugeon.— Ostioles in the animal and veget- 

 able kingdoms considered as a regulating apparatus, by M. J. J. 

 Andler. 



DIARY OF SOCIETIES. 



THURSDA }', January is. 

 Mathematical Society, at S.— On .-i Determinant Mch of « iiosi 

 mentsisthe product of* Factors: Prof. W. H. Metzler. —Propel 

 Hyper-space, in relation to Systems of Forces, the K - - 



Ele- 

 of 



....^.. ,.. — ., --- -— "f Rig'* 



Bod1es,°and"'ciiffo'r"d"\rParalJe7s'':' A."n. Whitehead.— .\ Simple Metbwl 

 of Factorising Large Composite Numbers of any unknown form: D. 

 Middle.— Zeroes of the Bessel Functions (second paper) : H. M. Mac- 

 donald.— Linear Substitutions and Inversions : Dr. G. G. Morrice.— On 

 the Reduction of a Linear Substitution to its Canonical Form: Prof. 

 Burnside, F.R.S. 

 Institution of Electrical Engineers, at 8. 



