:04 



NATURE 



[Jan. i, 1885 



in the form of a sharply corrugated circle, and the negative 

 electrode was placed in the centre, so that the resistance should 

 be low, it varied from '2 to 4 ohms according to the liquid used. 

 The E. M.F. was practically constant during its determination, as 

 the current drawn from the cell was only about - ooi ampere. 

 The minimum cell was of similar form to the maximum, only 

 the positive electrode was in the centre and w as a wire of about 

 0-5 mm. diameter, and the negative electrode was in the form of 

 a cylinder. By using cells of these forms he was able easily to 

 change either of the electrodes or the electrolyte. The method 

 of determining the minima electromotive forces was to short- 

 circuit the cell for several hours, and immediately on opening the 

 circuit to determine the E.M.F. The following are some of the 

 results that he obtained with an electrolyte of acidulated water, 

 2 parts in 1000 being sulphuric acid : — 



Electrodes E.M.F. in volts 



Negative Positive Maxima Minima 



Zinc, ordinary Carbon 



,, amalgamated ... Carbon 



,, ordinary Lead ... 



,, amalgamated ... Lead ... 



,, ordinary Copper 



,, amalgamated ... Copper 



,, ordinary Iron ... 



,, amalgamated ... Iron ... 



Iron 



... Zinc, ordinary ... — ...<o"09 

 ... Copper ... 0-49100-51 ... — 



An experimental reproduction on the screen of the pheno- 

 menon of the solar halo has been recently brought before the 

 Physical Society of Paris by M. Cornu. M. Cornu also dis- 

 cussed the phenomenon of the pink corona which has been visible 

 around the sun during the past lew months. He thinks it lias 

 its seat in the atmosphere at an elevation considerably higher 

 than the level of the cirrus clouds which give the common ring- 

 halo of 22 . According to M. Cornu the polarisation of the sky- 

 has been " profoundly modified " by the present phenomenon, 

 especially when viewed through red glass. 



Signor A. Ricco sends us a lengthy memoir on a new form 

 of electro-magnet invented by him. It consists of a sheet of iron 

 rolled into a spiral round an iron core, the convolutions being 

 separated by oiled paper. The current traverses the coiled 

 sheet, which thereby becomes powerfully magnetised. A spiral 

 of fort)- turns of insulated copper wire is added outside. The 

 lifting power of this magnet appears to be very great in propor- 

 tion to its weight. 



A pamphlet on the system of simultaneous telephony and 

 telegraphy invented by F. van Rysselberghe has lately appeared 

 from the, pen of M. Ch. Mourlon, secretary of the Societe 

 beige d'Electriciens. 



Dr. E. von Fi.eischl recently communicated to the Viennese 

 Academy a paper on the double- refraction of light in liquids. 

 Concentrated solutions of tartaric acid and of various sugars were 

 employed, also certain active oils, in a compound hollow prism 

 resembling a Fresnel's quartz combination in its general disposi- 

 tion. The research proves the existence of doubly-refracting 

 liquids ; but they possess no optic axis. The wave-surfaces are 

 in every case two concentric spheres. 



CHEMICAL NOTES 

 ATTENTION was lately drawn in these Notes to Schiff's recent 

 researches on the connections between the capillary coefficients 

 of various liquid carbon compounds and the structure of the 

 molecules of these compounds (see also Nature, vol. xxx. p. 

 618). The same subject has very recently been examined by 

 I. 1'raube (Ber. xvii. 2294). Traube thinks that the differ- 

 ences between the various capillary elevations observed by Schiff 

 arc too small to allow of trustworthy conclusions being drawn : 

 he has therefore undertaken a series of observations with aqueous 

 solutions of various classes of carbon compounds. Inasmuch as 

 the capillary elevation of water in a tube of -34 mm. radius is 

 about 41-5 mm., while that of most liquid carbon compounds 

 does not exceed 25 mm., Traube concluded that there will 

 probably be well-marked differences between the capillary ele- 

 vations of aqueous solutions, and mixtures of aqueous solutions, 

 of definite concentration, of various compounds of carbon. The 

 height in capillary tubes was determined for each solution for 

 varying degrees of concentration, and the results are stated for 



equal weights of compounds in equal volumes of solution. From 

 these results Traube draws the conclusions : — (1) The capillary 

 elevation of the solution of a compound decreases as concentra- 

 tion increases ; the differences of elevation are not equal for equal 

 increases in concentration. (2) The capillary elevations decrease in 

 a homologous series of carbon compounds as molecular weight in- 

 creases. (3) Isomeric compounds in solutions of equal concentra- 

 tion do not always exhibit equal capillary elevations. Schiff's gene- 

 ralisation, that the number of molecules of isomerides raised by 

 capillary action is equal, does not hold good for aqueous solu- 

 tions of isomerides. As in Traube's experiments the liquids 

 examined were of equal concentration, it follow s that the ratios 

 of the capillary elevations are equal to the ratios of the masses 

 of the dissolved compounds raised in the capillary tubes. 

 Calling the capillary elevation h, and the specific gravity of the 

 solution s, Traube considers the product // s, which he calls the 

 capillary coefficient of the solution. The value of h is condi- 

 tioned by the chemical constitution of the compounds examined. 

 If m — molecular weight of compound in solution, then the 



difference between - for solutions of two comoounds, within 



111 

 certain limits of concentration, is a constant which depends only 

 on the relative concentrations of the two solutions. The values 



of - for an homologous series, dealing with solutions containing 



equal masses of the compounds in equal volumes, are referred to 



the value of — for the first member of the series, and the 



in 

 differences thus obtained, when calculated for a tube I mm. 

 radius, are called the specific capillary constants of the com- 

 pounds in the series. The values of this quantity are almost 

 wholly dependent on the nature of the solution, perhaps only on 

 the nature of the dissolved substance, and are independent, 

 within certain limits, for each homologous series, of the absolute 

 concentration of the solutions, and are scarcely, if at all, 

 dependent on temperature. Traube thinks he is justified 

 from his experimental results in concluding that the differ- 

 ences between the capillary elevations of the solutions of 

 two analogous compounds are in the same ratio as the mole- 

 cular weights of the compounds. Thus, let //„ and lu x re- 

 present the capillary elevations of two solutions, of different 

 concentrations, of the compound with molecular weight m ; and 

 let h a and /ig 1 represent the capillary elevations of two solutions, 

 of the same concentration as those of the former compound, of 

 an analogous compound with molecular weight w,. Then, 

 according to Traube, 



li„ l.\. _ h 3 _ k B \ . 



therefore 



*« 



If, therefore, // a , /?„,, &c, are determined, the ratio — can be 



"') 

 found ; and if 111 is known, the value of the molecular weight of 

 the second compound (/«,) can be calculated. 



GEOGRAPHICAL NOTES 

 We are glad to see that at last there is some probability of 

 the almost unknown but certainly interesting country of Tibet 

 being opened up to outsiders. We know the frequent but un- 

 successful efforts which Prjevalsky and others have been recently 

 making to penetrate to Lassa. But now the Tunes Calcutta 

 correspondent informs us that the Regent of the Tashu Lama 

 at Shigatze has sent a most cordial reply to the letter which Mr. 

 Macaulay despatched to him from the frontier through the 

 agency of the Governor of Kambajong, and has also addressed 

 a letter to the Viceroy. With these letti rs, besides the silk 

 scarves which ordinarily accompany Tibetan correspondence, the 

 correspondent understands he lias sent some relics of the late 

 Tashu Lama himself, and has asked Mr. Macaulay to send him 

 a Tibetan-English dictionary and 1 hrase-book and some scien- 

 tific instruments. This is the first official communication re- 

 ceived from Tibet for about a hundred years. The correspondent 

 suggests that the Government should put our relations on a firm 

 footing by sending at once a friendly mission in connection with 

 the identification which tales place this year of the infant in 

 whom Tashu Lama is supposed to have been born again. 



