Feb. 23. 1888] 



NATURE 



407 



Physical Society, January 28. — Prof. W..G. Adams, F.R.S., 



Vice-President, in the chair. — In opening the proceedings the 

 •Chairman referred to the great loss which the Society had sustained 

 by the death of Dr. Balfour Stewart, their late President, and 

 -said that his loss would be deeply felt by the whole scientific 

 world. — The following papers were read: — On the effect of 

 magnetization on the thermoelectrical properties of bismuth, by 

 Vir. Herbert Tomlinson. — On the influence of magnetism and 

 temperature on the electrical resistance of bismuth and its alloys 

 with lead and tin, by M. Ed. von Aubel. — On a water-dropping 

 influence machine, by Prof. S. P, Thompson, — On the price of 

 the factor of safety in lightning-rods, by the same. It is here 

 shown, upon certain assumptions, that the safety against fusion 



f s 



varies as total cost X -^, ; where j = temperature of fusion 



p it I- k 

 of material above atmosphere, s = specific thermal capacity, 

 p = specific electric resistance, d = density, /; = cost in pence 

 per lb., and / = length of the conductor. If the total cost 

 and length are supposed to be given, the factor of safety 



Of the common metals-jiron has the greatest factor 



= / L 



pdi' 



of safety, being more than four times that of copper. Such 

 being the case, the author thinks it desirable that the Report of 

 the Lightning- Rod Conference be reconsidered. — On the optical 

 <lemonstration of electrical stress, by Prof. A. W. Riicker, 

 F.R. S., and Mr. C. V. Boys. A number of lecture experiments 

 were shown illustrating that electrical stress exists in the 

 dielectric separating two charged bodies. The bodies were 

 placed in carbon bisulphide, between two crossed Nicols, and on 

 electrifying them by means of a Holtz machine, light passed 

 through the analyzer. Two concentric cylinders gave a black 

 cross on the screen similar to those seen on interposing a plate 

 of so ne uniaxial crystal, and a model illustrating a charged 

 Leyden jar was shown. 



February 11. — Annual General Meeting. — Dr. J, H. Glad- 

 stone, F.R.S., Vice-President, in the chair, — The Chair- 

 man read the Report of the Council for the past year, and 

 expressed regret at the losses the Society had sustained by 

 the deaths of Dr. Stewart (their late President), Prof. Kirchhoff, 

 Mr. Coutts Trotter, and Prof. Humpidge. The Council regret 

 that no increase of mejibers has taken place during the past year, 

 and h ope that the advantages offered by the Society may be 

 more fully appreciated in future. Obituary notices of Dr. B. 

 Stewart, Mr. Coutts Trotter, and Prof. Humpidge were then 

 read. The Treasurer's Report shows that the financial condition 

 of the Society is very satisfactory. On the motion of Mr. Lant 

 Carpenter, seconded by Mr. Inwards, the Reports were adopted, — 

 The following gentlemen were elected members of Council for 

 the present year : — President : Prof. A. W. Reinold, F. R. S. 

 Vice Presidents : Dr. E. Atkinson, Prof. W. E. Ayrton, F.R.S., 

 Mr. Shelford Bidwell, F.R.S. and Prof. H, McLeod, F.R.S. 

 Secretaries: Mr. Walter Baily, and Prof. J. Perry, F.R.S. 

 Treasurer : Prof. A. W. Riicker, F. R. S. Demonstrator 

 and Librarian : Mr. C. V. Boys. Ocher members of Coun- 

 ■cil : Hon. R. Abercromby, R. H. M. Bosanquet, M. A., 

 W. H. Coffin, Conrad W. Cooke, Prof. F. Fuller, W. 

 N, Shaw, A. Stroh, Prof. S. P. Thompson, H. Tomlinson, 

 G. M, Whipple. On taking the chair the new President 

 •expressed his sincere thanks for the great honour the Society 

 had conferred upon him. Prof. Fuller proposed a vote of 

 thanks to the Lords of Committee of Council on Education 

 for the use of the rooms and apparatus of the Normal School 

 of Science, which was seconded by Mr. Shaw, and passed 

 unanimously. A cordial vote of thanks to the Council and 

 officers of the past year, moved by Dr. Blaikley, and seconded 

 by Prof. Ramsay, was dul/ acknowledged by the President. A 

 similar vote, proposed by Mr. Bosanquet, and seconded by Mr. 

 Hadden, to the auditors for the past year, was passed unani- 

 mously. — The meeting was then resolved into an ordinary science 

 meeting, at which the following papers were read : — On the 

 limit of refraction in relation to temperature and chemical com- 

 position, by Mr. T. Pelham Dale. — Note on the use of the 

 term "resistance" in the description of physical phenomena, 

 by Mr. R. H. M. Bosanquet. 



Paris. 



Academy oi Scien:es, February 13. — M, Janssen in the 

 chair. — On an an::ient process for rendering gens and vitrifica- 



tions phosphorescent , by M. Berthelot. The treatise in which 

 this process is described occurs in the collection of Greek 

 alchemists transcribed in certain manuscripts of the thirteenth 

 and fifteenth centuries (Bibliotheque Nationale, Nos. 2325 and 

 2327). It contains a series of purely technical receipts analogous 

 to those of the Leyden papyrus, some apparently of great 

 antiquity, explaining certain methods of "colouring artificial 

 precious stones, emeralds, carbuncles,'hyacinths, according to the 

 book taken from the shrine of the Temple." Several Egyptian 

 alchemists are mentioned, such as Agathodemon, the pseudo- 

 Moses, Ostanes, and Democritus, and the text leaves no doubt 

 as to the ancient practice of rendering certain gems phos- 

 phorescent in the dark by means of surface colouring prepared 

 from substances which are still known to possess such properties. 

 — On the properties of a new hydraulic machine intended for 

 irrigation purposes, by M. A. de Caligny. For this apparatus, 

 which has been for some time in use both at Aubois and on the 

 canal between Mons and La Louviere, the author claims the 

 advantages of great simplicity of structure as well as economy on 

 the first outlay. It may also be utilized for replenishing cattle- 

 troughs, and other secondary uses, at a minimum cost. It was 

 awarded a gold medal at the Antwerp Universal Exhibition. — 

 On the part played by the absorbing power of the soil in the 

 formation of the natural carbonates of soda, by M. Paul de 

 Mondesir. The paper deals with Berthollet's well-known theory 

 regarding the formation of Egyptian natron, and shows that 

 Berthollet's explanation is so far true that the marine salt really 

 furnishes the soda, and carbonate of lime, the carbonic acid. But 

 the reaction is neither direct nor continuous, and is produced in 

 two distinct phases. In the first, the soil reacts on the marine 

 salt, transforming it into chloride of calcium while yielding lime 

 and absorbing soda. In the second, which can set in only after 

 removal of the chloride of calcium, the bicarbonate of lime and 

 the carbonic acid extract the soda from the ground, replacing it 

 with lime. Berthollet's theory is thus left fundamentally intact, 

 but so modified as to become universally applicable. In fact, the 

 carbonate of soda is produced in all permeable calcareous soils in 

 proportion to the quantity of marine salt contained in them. — 

 Observations of the new planet 272, discovered on February 4, 

 at the Observatory of Nice, by M. Charlois. The observations, 

 including right ascension, polar distance, and the positions of 

 comparison stars, extend over the period from February 4 to 

 February 9. When discovered the planet was of 13 '5 magnitude. 

 — New obseri^ations on the variability of Saturn's rings, by M. 

 E. L. Trouvelot. It is pointed out that the observations made 

 during the last few years by Perkins, Offord, Davis, Stanley 

 Williams, Stroobant, and others, all tend definitely to establish 

 the proposition announced by the author in 1884, that, so far 

 from being stable, the rings of Saturn are on the contrary 

 essentially variable, and subject to constant fluctuations. The 

 same truth is confirmed by the author's own observations made 

 in 1886 and 1887 at the Observatory of Meudon, and here com- 

 municated to the Academy. — Theorems on Campbell's algebraic 

 equations and quadratic functions, by Father Aug. Poulain. 

 Newton, or rather Campbell, formulated a very simple rule 

 for determining the existence of the imaginary roots in algebraic 

 equations. The author here proposes a few theorems, by means 

 of which the application of this law may be extended and 

 the accompanying calculations much simplified. — On chemical 

 equiUbria, by M. P. Duhem, In a recent note M, H. Le 

 Chatelier announced that the numerical laws of chemical 

 equilibrium, as deduced from the two principles of thermo- 

 dynamics, may be expressed in a simple way by means of 

 M, Massieu's characteristic function H'. Here it is shown that 

 this law may be thus formulated : The variation imposed on M. 

 Massieu's function H' by a virtual isothermic modification of the 

 system is equivalent to zero, . It is further pointed out that the 

 reiults obtained by M. Le Chatelier are practically identical with 

 those arrived at by the author during a series of investigations 

 spread over several years. — O.i the mineralizing action of the 

 alkaline sulphides: reproduction of chrysoberyl, by MM. P. 

 Hautefeuille and A. Perrey. During a protracted series of re- 

 searches on the mineralizing action of the sulphides, the authors 

 have succeeded in obtaining the crystallization of glucine, the 

 separation of alumina and glucine, or inversely the reproduction of 

 the aluminate of glucine, a combination which occuri in nature, 

 and which is known by the name of cymophane (chrysoberyl). 

 A simple process is described by means of which from a com- 

 bination of glucine and alumina extracted from the emerald the 



