February 9, 191 1] 



NATURE 



497 



Institution of Mining and Metallurgy, January 25. — 



Mr. Edgar Taylor, president, in the chair. — .\d\ourned 

 discussion. H. C. Bayldon : Notes on Chilian mills in 

 Russia. In this paper the author provides a useful and 

 instructive treatise on the slow-running Chilian or " Edge 

 runner " mill, invariably used in Russia for crushing gold 

 ores as a preliminary to amalgamation, &c. After a brief 

 historical summary, the paper gives descriptions of the 

 standard type of Chilian mill now in use, and of the 

 milling methods adopted in Russia, which are followed 

 by notes on an improved type of Chilian mill and milling 

 plant recently introduced. The descriptions are suitably 

 illustrated, and there are ample statistics relating to mills 

 and their efficienc}'. The author is of opinion that if the 

 same amount of thought and attention were devoted to 

 this tyf)e of mill as has been given to the heavy stamp 

 plus tube mill combination in South Africa, it would prove 

 a serious rival and give a product nearer to the ideal 

 aimed at on that goldfield. — N. A. Logrgin : Notes on 

 placer mining, with special reference to hydraulic sluicing. 

 The author here gives the results of a wide experience in 

 placer mining conducted on the hydraulic sluicing system 

 in the form of a collection of practical hints with regard 

 to the whole of the process involved, from the initial 

 determination of the value of the gravel to be mined 

 down to the most suitable location of the dump. As 

 might be anticipated, the chief points dwelt upon relate 

 to the arrangement of an efficient supply of water to feed 

 the " giants " and " deflectors " at the face of the mine, 

 as this constitutes the crux of the problem, next in import- 

 ance to which comes the construction of the flume in 

 which the gravel is washed and relieved of its gold 

 contents. 



Edinburgh. 

 Royal Society, Decemter 19, 1910. — Prof. Bower, vice- 

 president, in the chair. — Prof. A. C. Seward : The 

 Jurassic flora of Sutherland. This contained a general 

 account of the fossil plants collected by Hugh Miller, Dr. 

 Marcus Gunn, and Mr. Archer from the Kimeridgian 

 strata on the coast of Sutherland. Dr. Gunn's collection 

 has been recently acquired by the British Museum. 

 Thanks were expressed to Mr. H. B. Woodward for notes 

 on the geology of the Sutherland plant beds. The flora of 

 Sutherland, with a few types collected by Hugh Miller at 

 Eathie (Cromarty), may be regarded as representing the 

 Jurassic flora of Scotland as a whole, the specimens re- 

 corded from western localities being very few and frag- 

 mentary. The Scottish Jurassic flora includes several 

 widely distributed species previously described from the 

 Inferior Oolite series of Yorkshire and elsewhere, together 

 with some Wealden types. From a botanical point of 

 view, the Kimeridgian flora of Sutherland is interesting 

 chiefly on account of the additional evidence it affords of 

 the general uniformity of the Jurassic vegetation of the 

 world, and as demonstrating the occurrence in north-west 

 Europe in the Jurassic era of such genera as Hausmannia, 

 Laccopteris, Araucarites, &c., which are now represented 

 by species in the southern tropics or in south temperate 

 latitudes. — Dr. A. A. Lawson : Phase of the nucleus 

 known as synapsis. The argument was that synapsis was 

 due, not to contraction, as generally supposed, but to 

 growth. — Prof. R. J. A. Berry : The sectional anatomy of 

 the head of the Australian aborigine. 



January 9. — Prof. Hudson Beare, vice-president, in the 

 chair. — ^.\lan W. C. Menzies : A method for determining 

 the molecular weights of dissolved substances by measure- 

 ment of lowering of vapour pressure. The apparatus was 

 so arranged that the temperature of the liquid, with the 

 dissolved substance in it, was sustained at the temperature 

 of the vapour coming from the boiling pure liquid, while. 

 at the same time, part of the surface of the impure liquid 

 was subjected to the pressure of this vapour, while the 

 rest of the surface was subjected to the pressure of its 

 own vapour, which was somewhat less, because of the 

 dissolved substance. The difference of pressure was 

 balanced by the difference of height of the two surfaces 

 of the liquid. The method was found to be easy of 

 manipulation, and to lead to satisfactory measurements. 

 — Dr. George Green : The modus operandi of the prism. 

 The action of a prism on a light " pulse " incident upon 

 It was illustrated by means of the analogy between the 

 pulse problem and the hydrodynamical problem presented 

 NO. 2154, VOL. 8sl 



by a point disturbance moving uniformly over a liquid 

 surface. Taking the ship-wave pattern to represent the 

 general form of wave disturbance within a prism immedi- 

 ately after the incidence of a light pulse, the author 

 applied the theory of group velocity to arrive at the general 

 features of the wave system after emergence from the 

 prism, deriving the usual formula for the resolving power. 

 — Dr. John Brovwnlee : The relation of the mono- 

 molecular reaction of life processes to immunity. The 

 simple law of exponential decay was found to govern 

 many of these processes. An interesting example was the 

 mortality due to scarlet fever at different ages ; the 

 statistics for two large towns showed that this mortality 

 amongst children diminished exponentially with increase 

 of age. 



Paris. 

 Academy of Sciences, January 30. — M. Armand Gautier 

 in the chair. — H. Deslandres : Researches on the move- 

 ments of the solar atmospheric layers by the displacement 

 of the lines of the spectrum. Lack of symmetry and 

 peculiarities of the phenomenon. The author gives a 

 short historical survey of the whole of the work done in 

 this field, and proceeds to discuss in detail the observations 

 made at the Observatory of Meudon from 1892 onwards. 

 Special attention is given to the displacements of the K^^ 

 line and the views which have been put forward to explain 

 the observed facts. — G. Lippmann : The acticm of 

 external forces on the pressure of saturated vapours and 

 the gases dissolved in a liquid. The lowering of the 

 vapour pressure of a liquid in a capillary tube was first 

 demonstrated by Kelvin. The explanation put forward by 

 Kelvin involves the constancy of the vapour pressure 

 throughout the whole column of the liquid, the variation 

 being assumed to be produced in a discontinuous manner 

 in the meniscus. The author proposes another explana- 

 tion, according to which, for equilibrium, the tension of 

 a dissolved gas varies with the level according to the same 

 law as the pressure of the gas in the interior of the 

 liquid. Saturated vapour can be regarded as a particular 

 case of this theorem. — M. Gouy : The existence of a 

 periodic element in the magneto-kathodic radiation. It is 

 known that in a high vacuum the magneto-kathode bundle 

 emitted by a wire serving as a kathode forms a luminous 

 sheet, separated from the kathode by a dark space. 

 Under certain conditions, dark and light fringes appear 

 in this luminous portion. It has been found that the 

 maximum intensity corresponds to rays the lengths of 

 which are exact multiples of a certain length, a, which 

 is inversely proportional to the value of the magnetic 

 field. — D. Th. Esorofff : Sets of measurable functions. — 

 R. Bourgeois : A cause of an instrumental error in the- 

 measurement of a base line. In the determination of a 

 base line at Blida, invar wires, standardised at the Inter- 

 national Bureau, were used. Certain discrepancies 

 appeared in the results, outside the ordinan." experimental 

 error, and these were finally traced to the inclinations of 

 the rule from the horizontal. The error was eliminated 

 when the measurements were made in opposite directions 

 over the same line and the mean taken. — Torres 

 Quevedo : A mechanical construction for the linkage 

 expressed by the formula d^ da = tan w. — Auguste Rigrhi : 

 The probable ionising action of the magnetic field. Some 

 experiments are described in which the discharge potentials 

 between metallic electrodes in an exhausted tube were 

 measured in magnetic fields of varying strength. The 

 hypothesis that the magnetic field can produce ions offers 

 a possible explanation of the observed facts. — C. Limb : 

 Compounding alternators by means of electrolytic valves. 

 — E. Urbain, CI. Seal, and A. Fe«ge : A new type of 

 arc lamp having a mercury kathode and giving white 

 light. An arc is struck in a quartz tube between an anode 

 of tungsten and a kathode of mercury. The light is prac- 

 tically white, spectroscopic examination showing a con- 

 tinuous spectrum with the mercury lines superposed. The 

 yield is high (0-45 watt per candle), and the arc w'orks 

 with a potential difference of 12 volts ; the voltage can be 

 increased by the presence of an inert gas in the tube. — 

 J. Bosellf : Reaction velocities in heterogeneous systems. 

 — Louis Hackspill : The density, coefficient of expansion, 

 and change of volume on fusion of the alkaline metals. 

 The metals (caesium, rubidium, potassium, and sodium> 

 were distilled in a high vacuum immediatelv before each 



