igo 



NA TURE 



[December 22, 1898 



accompanied by anomalous absorption, receives a negative con- 

 firmation in the esters of the fatty acids and benzoic acid, which 

 show neither. Other esters and alcohols show a rough ap- 

 proximation to Drude's formula. In the glas.ses, the relation 

 between absorption and dispersion is undefined. — Limits of the 

 solid state, by (\. Tammann. 0.stwald considers il possible 

 that the transition from the liquid to the'crystallised state 

 takes place continuously along a Thomson-van-der-Waals 

 isothermal. The author shows that this assumption implies the 

 possibility of four volumes at the same pressure, and that the 

 liquid isothermals may be followed up beyond the point of 

 intersection with the crystal isothermals. This eliminates what 

 Ostwald calls the meta-stable phase of crystallisation. — Con- 

 tact electricity between metals and liquids, by A. Heydwciller. 

 The author introduced minutely sub-divided metals into a nar- 

 row tube containing an electrolyte, and passed a current through 

 the latter. Any contact electrification was then indicated by 

 motion of the particles. He thus tested Coehn's rule, accord- 

 ing to which bodies with a higher dielectric constant are posi- 

 tively charged by contact with bodies of a lower dielectric con- 

 stant. Platinum, gold, tin, and other metals, immersed in 

 various mixtures of water, chloroform, and acetone, show an 

 agreement with Coehn's rule, but not when immersed in 

 alcohol. — Use of a vacuum tube for thermal insulation, by A. 

 Weinhold. In connection with d'Arsonval's claim of having 

 employed the princii)le of Dewar's double bottle in 1887, the 

 author mentions that he described the same apparatus as long 

 ago as 1881, in the first edition of his " Physikalische Demon- 

 strationen." 



The current number of the Izveslia of the East Siberian 

 branch of the Russian Geographical Society contains several 

 'Valuable papers. — M. Prein gives a list of 424 phanerogam 

 plants collected in the west of the northern parts of Lake 

 JSaikal, and his list contains several species which are new for 

 this interesting region. — A paper by S. V. Vastremski, on the 

 ancient beliefs of the Vakutes (who belong to the Turkish stem), 

 •not only shows that their religion has a good deal in common 

 with the religion of the Mongols, but also reveals traces of a 

 ■worship of good-willing deities, which worship was practised 

 by so-called ''white shamans" (the shaman is the witch- 

 priest). Traces of this worship, which has been intermingled 

 in recent times with Christianity, are now found in epical 

 poetry and popular songs only, but " white shamans " 

 were known to exist not further than ten years ago. At 

 the present time the " black shamans," or worshippers and 

 conjurers of the bad-willing deities only, are retained. — M. S. 

 Peretolchin gives an account of his ascent of the Munku-Sardyk 

 peak in the Sayans, and describes a small glacier on its southern 

 slope, surrounded by old moraines testifying to its former 

 greater extension. Phanerogams were found up to :in altitude of 

 10,230 feet. — N. A. Witaszewski gives interesting copies of 

 inscriptions on the crags of the Olekma, — All papers are summed 

 up in German. 



In the Jotirnal of Botany for November and December, 

 Col. H. \V. Feilden continues and concludes his list of the 

 " Flowering Plants of Novaya Zemlya," iVc, 195 species in all, 

 besides four Vascular Cryptogams. — Mr. E. S. Salmon describes 

 and figures a moss new to the British flora, Calharinca tenella, 

 lately found in Kent. — Messrs. H. and J. Groves describe and 

 figure another very interesting addition to the British Crypto- 

 gamic flora, Nitella hyalina, discovered in Cornwall, one of the 

 most beautiful of the Characex-, distinguished from other 

 species of the genus by the presence of secondary branchlets. 



SOCIETIES AND ACADEMIES. 

 London. 



Royal Society, November 24. — "On the Condensation 

 Nuclei produced in Gases by the Action of Ronlgen Rays, 

 Uranium Rays, Ultra-violet Light, and other Agents." By 

 C. T. R. Wilson. 



By means of expansion experiments the degree of super- 

 saturation necessary to cause water to condense on nuclei from 

 various sources was determined. The nuclei produced in air or 

 hydrogen by Kbnlgcn rays or Uranium rays, or by the discharge 

 of electricity from a pointed platinum wire, or by the escape of 

 negative electricity from a zinc plate exposed to ultra-violet 

 ligiht, all require the same expansion (vjv-^ = I "25, correspond- 



NO. I 52 I, VOL. 59] 



ing to a fourfold supersaturalion) in order thai water may con- j 

 dense on them. In moist air or oxygen exposed to ultra-violet 

 light, nuclei are produced throughout the volume of the gas 

 exposed to the rays ; when the radiation is weak, these reqiure 

 as great a degree of supersaturalion as the various nuclei aoove 

 mentioned in order that water may condense on them ; butwUh 

 stronger radiation they appear to grow, and the expansion re- 

 quired to make water condense on them then depends on the 

 intensity of the ultra-violet light, and on the time for which the 

 gas has been exposed to the rays before expansion. With very 

 strong ultra-violet light the growth of the nuclei continues even 

 in unsaturated air till they become visible as a fog. Sunligh' 

 produces in air nuclei resembling those produced by wealv 

 ultra-violet light. Certain metals in contact with moist aii 

 produce nuclei always requiring great supersaturation in order 

 that water may condense on them. This effect is mo^' 

 strongly exhibited by amalgamated zinc, with which com- 

 paratively dense fogs may be obtained on expansion. 



It was found that the nuclei produced by X-rays or Uranium 

 rays may readily be removed by applying an electric field, show 

 ing that the nuclei are identical with the ions to which thi 

 conducting power of the gas when exposed to the rays is due 

 Similar experiments with the nuclei produced by the action c; 

 ultra-violet light on moist air, and with those resulting from the 

 presence of metals, showed that such nuclei do not move in 

 an electric field. This is in agreement with the absence <•( 

 conducting power. 



Royal Microscopical Society, November 16. — Mr. E. M. 

 Nelson, President, in the chair. — ^The President read a papci 

 describing a very large and elaborate binocular microscope 

 possessing many original features ; it was designed and made 

 some years ago by a friend. The description was illustrated b\ 

 an excellent photograph of the instrument shown upon the 

 screen. — Mr. Beck exhibited two slides of AinphipUwa 

 pellucida, mounted by Prof. Hamilton Smith in his high refrac- 

 tive medium ; they were shown under Vt achromatic oil 

 immersion objectives of N. A. I "O, and i '25, the diatoms undei 

 the former showing re-solution very fairly, bur those under the 

 latter were re-solved most satisfactorily. — Mr. Michael calleii 

 attention to the slides of diatoms mounted in high refractive 

 media, which Mr. Curtieshad brought for exhibition. — Dr. Hebl 

 said there was a paper contributed by Mr. .'V. W. Waters, "on 

 Bryozoa from Madeira," of which he gave a short rhiimi. Mr. 

 Michael remarked that a systematic paper such as this would 

 prove of considerable value to those who were studying the 

 subject. Mr. Waters was at the present moment the bes' 

 English authority on the Bryozoa, and their knowledge of these 

 organisms had been systematised and made available largel) 

 by his contributions to the subject and by his skill as a 

 draughtsman. . 



Mathematical Society, December 8. — Lieut. -Colonel 

 Cunningham, R.E., Vice-President, in the chair. — Majoi 

 Macmahon, 1\..\. , F.R.S., communicated a discovery he had 

 recently made in the theory of compound partitions. — Mr. J. E 

 Campbell read a paper on simultaneous partial diflerential 

 equations. — The following papers were communicated in 

 abstract : On hyperplane coordinates, by W. H. Young.— 

 On atheorem allied to Laplace's, by Prof. W. H. Melzler.— Twi 

 pioblems of wave propagation at the surface of an elastic solid, 

 by T. J. Bromw ich. The two problems deal with the velocity 01 

 propagation of waves in hypothetical elastic solids, \n attempt 

 is made to find causes for the discrepancy between the observed 

 velocities of earthquakes and those calculated by theory. The 

 first case considered is that of a thin elastic shell (this case 

 appears to have been solved by Lord Rayleigh, but it has not 

 apparently been thought worthy of publication by him). The 

 author finds that, w ith the elastic constants given by Prof. Milne 

 as representing the nature of rocks at the surface of the earth, 

 the deduced velocity has a value agreeing much more nearly 

 with observed velocities than the velocity deduced from Lord 

 Rayleigh's paper in t)ie Proieedings (vol. xvii.). The second 

 problem .solves the hypothetical case of a thin skin fastened I' 

 the surface of a solid, the elastic constants of the two materiab 

 being suppose<l different. As might be expected the eflect 01 

 the skin is not large, and the result only indicates that it i* 

 necessary to know the elastic constants at a depth comparable 

 with a wave-length, before we can get a satisfactory comparison 

 between theory and observation. Also by the same author, the 

 influence of gravity on vfavcs in an elastic solid, with especial 



