November 30, 1899] 



NATURE 



19 



In this paper the three formula; considered in the preceding 

 communication are applied to the known experimental results 

 upon the conductivities of mixtures of liquids. The author 

 finds that the least satisfactory formula is the first one, whereas 

 the least unsatisfactory is the logarithmic one. Mr. Appleyard 

 said that it was frequently of importance to be able to deter- 

 mine the resistance of a mixture of gutta-perchas from the 

 known resistances of component parts. He had attempted, 

 without success, to do this by means of the old formulae, and 

 he would be interested to see whether Dr. Lees' logarithmic 

 formula gave better results. In electrical work Mr. Appleyard 

 pointed out that the nature of the contacts affected the conduc- 

 tivity, the resistance of a sheet of rubber being different when 

 measured between metal plates and mercury sheets. Mr. Camp- 

 bell said that the difference between the calculated and observed 

 results might be due to the thermoelectric properties of the 

 materials. Lord Rayleigh had observed that the high resistivity 

 of alloys might be due to a back E.M.F. produced by the 

 contact of dissimilar metals. Mr. Campbell said that he had 

 measured the resistances of ferro-nickels both with direct and 

 alternating currents, and found them the same in the two cases. 

 In reply, Dr Lees said that all his experimental work on con- 

 ductivity had been carried out with mercury contacts.— The 

 Society then adjourned until December 8, when, by the invi- 

 tation of Prof S. P. Thompson, the meeting will be held in 

 the Physical Laboratory of the Finsbury Technical College. 



Chemical Society, November i6. — Prof. Thorpe, Presi- 

 dent, in the chair. — The following papers were read. — The 

 chlorine derivatives of pyridine. Part IV. The constitution of 

 the tetrachloropyridines, by VV. J. Sell and F. W. Dootson. 

 The authors have determined the constitutions of the three 

 known and theoretically possible tetrachloropyridines. — Contri- 

 butions to our knowledge of the aconite alkaloids. Part XV, 

 On japaconitine and the alkaloids of Japanese aconite, by W, R. 

 Dunstan and H. M. Read. The authors show that Japanese 

 aconite, A. Fischeri ("Kuza uzu "), contains japaconitine, 

 CoiIl29(OMe)4(OCMe)(OCPh)N03, which, contrary to the views 

 ot many investigators, is chemically distinct from aconitine. — 

 The dissociation constants of very weak acids, by J. Walker 

 and W. Cormack. Using a special form of apparatus, the 

 authors have determined the electrical conductivity of solutions 

 of feebly acid substances, such as phenol, hydrogen sulphide 

 and acetic, carbonic, boric and hydrocyanic acids; the behaviour 

 observed is in accordance with Ostwald's dilution law. — Pre- 

 paration and properties of solid ammonium cyanate, by J. Walker 

 and J. K. Wood. Pure solid ammonium cyanate may be ob- 

 tained by mixing cooled ethereal solutions of ammonia and 

 cyanic acid ; its molecular heat of transformation into solid urea 

 is 49 K, whilst in aqueous solution this constant is 75 K. — 

 Etherification of derivatives of jS-naphthol, by W. A. Davis. — 

 On the determination of transition temperatures, by H. M. 

 Dawson and P. Williams. The authors' method of determining 

 transition temperatures depends upon ascertaining the point at 

 which the two branches of the density or electrical conductivity 

 curves at temperatures above and below the transition point, 

 intersect each other. — Constitution of amarine, of its supposed 

 dialkyl- and diacyl-derivatives and of isoamarine, by F. R. 

 Japp and J. Moir. The authors regard amarine as a CM-diphenyl 



CHPh.NH^ 

 compound of the constitution | x^CPh, Snape's iso- 



CHPh— N^ 

 amarine being the corresponding /rawj-isomeride ; the latter is 

 readily obtainable by fusing amarine with sodium or heating its 

 hydrochloride above the melting point. — The atomic weight of 

 nitrogen, by G. Dean. . The ratio Ag : AgCN was found to be 

 107-93 : 133962, whence CN = 26-032 and N = I4*03i if 

 C =: 12-001. 



Mineralogical Society, November 14. — Prof. A. H, 

 Church, F,R.S., President, in the chair.— Dr. E. Hussak and 

 Mr. G. T, Prior gave an account of a new Brazilian mineral, 

 Florencite, a hydrated phosphate of aluminium and cerium 

 earths (3Al.,03.Ce203.2P205.6H20), crystallising in the rhom- 

 bohedral system. The mineral is isomorphous with the recently 

 discovered Hamlinite, to which it is also very similar in chemical 

 composition ; the strontium and barium of Hamlinite being re- 

 placed in Florencite by cerium earths,— Mr, A. Hutchinson 

 described a new mineral, Stokesite, from Cornwall, of peculiar 

 chemical composition. It is a hydrated silicate of tin and 

 calcium, CaO. Sn02.3Si02, 2 H^O, and crystallises in the ortho- 

 rhombic system in forms closely resembling gypsum, from which 



NO. 1570, VOL. 61] 



it is easily distinguished by its much greater hardness,— Mr. R. 

 H. Solly contributed a paper on sulpharseniles of lead from the 

 Binnenthal, and gave descriptions of the crystallographic 

 characters of the rare minerals. Rathite and Jordanite. Analyses 

 made by Mr. H. [ackson gave to Jordanite the ordinary formula, 

 4PbS.As2S3, and lo Rathite the formula, 3PbS.2AsoS3. — Mr, 

 L. J. Spencer described complex twinned crystals of Stanniteon 

 specimens from Bolivia collected by Sir Martin Conway. The 

 crystals appear to be tetragonal, with crystal element close to 

 that of copper-pyrites. The analysis by Mr. G. T. Prior tends 

 to confirm the usually accepted formula. 



Royal Meteorological Society, November 15.— Mr. F. C. 

 Bayard, President, in the chair. — Mr, R. II. Curtis read a pwiper 

 on the diurnal variation of the barometer in the British Isles. The 

 principal features of a curve exhibiting the diurnal march of 

 barometrical pressure are two minima and two maxima — the 

 first minimum occurring early in the morning and the second in 

 the afternoon, while the first maximum falls in the forenoon and 

 the second not far from ten o'clock in the evening. In the 

 tropics the oscillation may amount to as much as a tenth of an 

 inch, but its amplitude decreases as the latitude increases, and 

 the greatest amplitude in the British Isles amounts to not much 

 more than three-hundredths of an inch. The author discusses the 

 mean hourly readings of the barometer from twenty-five years' 

 observations, 1871-95, at four observatories maintained by the 

 Meteorological Council, viz. Kew, Aberdeen, Falmouth and 

 Valencia. The author is of opinion that the primary cause of 

 the diurnal oscillation of the barometer is solar radiation, and 

 that its amplitude is chiefly determined by the temperature of 

 the lower strata of the atmosphere. The relative magnitudes of 

 the different phases of the barometer oscillation, as observed, 

 depend t largely upon the geographical position and physical 

 surroundings of the place of observation, in so far as these are 

 capable of modifying its temperature conditions, and especially 

 the relative distribution of temperature over the regions 

 immediately surrounding it. — Mr. G. J. Symons, F.R.S., 

 described some experimental observations which he made 

 during the hot weather in July with two thermometers one foot 

 below the surface of the ground, with the view of ascertaining 

 (i) the influence of slight shade, {2) the amount of daily range, 

 and (3) the approximate curve of daily fluctuation. 



Paris. 

 Academy of Sciences, November 20, — M. van Tieghem 

 in the chair, — ^Note on the Leonids, by M, Lcewy, An ac- 

 count of the results obtained in various French observatories on 

 the Leonid swarm. The results were disappointing. At Paris 

 only thirty-three Leonids were seen on three nights ; at Algeria, 

 sixty-five in two nights ; at Lyons, forty during three nights ; 

 at Toulouse, forty-three. The most favourable conditions for 

 observations appear to have existed at Marseilles, where twenty 

 shooting stars were seen on the night of the 13th, seventy-one 

 on the 14th, and forty-three on the 15th, or 134 in all.— Note on 

 the observations of the shooting stars known as the Leonids, 

 made at the Observatory of Meudon, by M. J. Janssen. In 

 order to prevent the possible interference of clouds or fog with 

 the observations, two balloons were employed, at an altitude of 

 about 200 metres. Full details will be given in a later paper. — 

 On the course of a system of plane waves, laterally indefinite, 

 moving in an isotropic heterogeneous medium, formed of plane 

 parallel layers, by M. J.Boussinesq. — Action of fluorine andhydro- 

 fluoric acid upon glass, by M. Henri Moissan. The statement of 

 Louyet, that anhydrous hydrofluoric acid does not attack glass 

 is shown to be based upon a misconception, since although 

 under certain conditions glass maintains its polished surface in 

 contact with hydrofluoric acid, it can be shown to have been 

 attacked by its loss of weight. In the present experiments 

 glass was invariably found to be attacked at the ordinary tem- 

 perature by gaseous hydrofluoric acid, even although very care- 

 fully dried. In the first experiments made with fluorine, a 

 similar effect was observed ; but this was afterwards found to 

 be due to the presenceof a minute trace of hydrofluoric acid. Pure 

 fluorine, freed from traces of acid by passing through a V-tube 

 cooled in liquid air, may be kept in sealed glass bulbs for weeks 

 without the glass being attacked.— Observations of the Leonid 

 swarm of November 13 to 16, 1899, made at the Observatory of 

 Paris, by M. G. Bigourdan.— Observations of Leonids 

 at the Observatory of Toulouse, by M. Baillaud.— 

 Observation of the Leonid swarm at the Observatory 

 of Meudon, by M. H, Deslandres, —Observations of the 



