43- 



NATURt 



[January 30, 1919 



OUR A SI RO.XOMICAL COLl \1 \ 



■ 1 \ 1 1 1 . I'h.' following observations ace 



Hamburg. Positions are foi 1 quinox of 



19180 : — 



G.M.T. R.A. 



Dec. 21 7 I s 1 

 ->4 * 57'8 



3 56 56-8 

 3 56 212 

 3 5" 8 ! 

 3 56 82 



,., 8 ,., 



13 24 19 



'3 34 -° 



14 4 2 



2(1 6 4«-S 



31 II in. I 



The magnitude was 15-0. 

 Continuation of ephemi 



R. \. X. I '• ' 1 ■- Log .1 



h. m % 



Feb. 4 4 10 50 17 51 03370 02106 



8 421 S 1817 



u 4 25 44 18 42 0-3435 0-2408 



16 4 30 3b 19 6 



20 4 35 44 19 30 °-35°° 0-2699 



H 4 4' 7 '9 S3 



28 4 46 43 20 15 0-3566 02980 



On December 26 the ephemeris needed the corrections 

 + is., o-o' 



A Curious Feature on Jupiter. — On the nighl of 

 January 10, at about 11 p.m., Mr. Frank Sargent, of 

 Bristol^ observed a luminous protuberance on the 

 eastern edge of Jupiter. It was situated on the equa- 

 torial side of the north equatorial belt. He watched 

 it for some time, and it was visible as a white spol 

 well within the limb of Jupiter, but grew fainter as it 

 advanced further on the disc. Clouds interfered and 

 prevented a transit being taken, but on the following 

 night Mr. Sargeiil re-detected the object, and it was 

 on the central meridian at about 6.464 though so faint 

 as to.be scarcely perceptibLe. He saw it projecting 

 from the western limb .tl about 9.5 p.m., when it was 

 quite bright and ven easil.) distinguishable. Lumin- 

 ous projections of this kind are often visible on 

 Macs, and are effects of irradiation, but, in the case ot 

 Jupiter, where the atmosphere is considerably denser, 

 the conditions are very different, and it seems probable 

 that the feature observed on Jupiter may have been a 

 real prominence, or it would have been obliterated 

 amid the densi vapours on the limb of the planet. 



The Paris-Washington Longitude.— Vol. ix. of 

 the Publications of U.S. Naval Observatory contains 

 the details of the determination of this longitude by 

 wireless telegraphy in 1013 and 1914. The transit 

 instrument-- used were of 3-in. aperture, with travel- 

 ling wires driven h\ electric motors. Every transit 

 was observed with the telescope in both positions, 

 thu-. eliminating collimation and pivot errors. There 

 were two transit instruments at each station — one 

 for a French, the other tor an American observer. 

 The observers interchanged stations when hall th< 

 rations wen obtained. The level error was ascer- 

 ed by striding levels, the azimuth by meridian 

 nibined with polar stars. High stars, on both 

 zenith, were used tor clock error, thus 

 minii; tii ' ffei 1 ol an erroneous azimuth. 



The wi i li ss signals were sent from Radio (Virginia) 

 and the Eiffel Tower. The power at Radio was 

 70 kilowatl and the wave-length 2500 metres. A 

 rhythmii f signals was sent, controlled by a 



pendulum, thi period of which was o-oos. M.T. Co- 

 incidences oi een the Radio signals and the 

 ticks of a mean-tim I ronometer were noted, a similar 

 comparison being ignals of the sidereal 

 clocks, the errors were obtained from fhe 

 transit observations. 



The double-transmission lime over the distance of 

 3840 miles is C0429S. bj American observers, anil 



NO. 257O, VOL. I02] 



. ■"! 24s. by the French. The deduced speed is 

 [80,000 j [2,000 miles p.s., praeliralK thai of light. 



The final result for Washington-Paris is 

 «h. 17m. 36653s. ±0-00313. The result for period ii. is. 

 however, o-o6s. greater than that for period i. 



The seconds cA the longitude as given bj cabi 

 exchanges in 1866, 1870, 1872, and 1892 were 36-563., 

 36.73s., 36-(>i|s., and 31&-70S. respectively. The mean is 

 36-&7S., very near the new determination'. The longi- 

 tudes of several other American observatories 

 deduced by the same wireless signals. The n suits are 

 appi in led to the report. 



THE ELECTROLYTIC DISSOCIATION 



THEORY. 



AMONG scientific gatherings the general disi 

 •** siuns of the Faraday Society have come to 

 occupy a very high place on account of their repre- 

 senlalive character and practical value. The latest 

 of these discussions, on the present position of 

 the theory of ionisation, held on January 21, was 

 favoured by an interesting contribution from Prof. 

 Arrhenius himself, the last sentence of which is as 

 follows: — "On the whole, it may be said that the 

 dissociation theory corresponds as well with experience 

 as may be expected in the present state of our know- 

 ledge." Nowadays few will quarrel with this dictum. 



All hough the discussion reflected the general opinion 

 that the dissociation theory of solution is the only 

 one worth serious consideration, it also showed that 

 there are still many unsolved problems in connection 

 with solutions. Among these the following deserve 

 special mention : — (1) The question of hydration or, 

 more generally, "solvation" of the ions; (2) the 

 problem of strong electrolytes — that is, the fact that 

 the ionic equilibrium in strong electrolytes does not 

 follow the law of mass-action, which applies so 



itelv to weak electrolytes (e.g. organic acids); 



and (3) the question of the chemical activity ot - 



and non-ionised molecules. 



Most chemists now consider that ions in solution 

 are associated with the solvent to a greater or less 

 extent. Some go further, and adopt the view first 

 put forward tentatively by van. der Waals in 1S91 that 

 iiion with the solvent is the determining causi 

 ol ionisation, and that the required energy comes from 

 the heat of hydration of the ions. Although this 

 suggestion is at first sight a plausibl. one, ii is still 

 unsupported by any convincing evidence, and, in any 



is not likely to furnish a full explanation of the 

 me, hanism of ionisation. 



Further, the many attempts made to determine the 

 degree of hvdration of the ions have so far not been 

 very successful: Mr. W. R. Bousfield, who con- 

 tributed two papers to the discussion, has calculated 



gree of hydration of certain ions on the assump- 

 tion (bat an ion (with associated water molecules) can 



eated as a small sphere moving through the 

 solvent, and that the radius of the comples can be 

 calculated by means of the well-known formula ot 

 Stokes. Dr.' H. Sand now finds that the application 



formula in the manner adopted by M> 

 BOusfield gives a value for the volume of the hydroxyl 

 ioi about one-thirtieth of that obtained by. other 

 ni. thods, .mil In- draws the important conclusion that 



's formula cannoi be applied to particles of 

 molecular magnitude. 



Tin- discussion of the problem of strong electrolytes 

 proved of special interest on account of the recent 

 work of Messrs. Washburn and Weiland in Ami 



SOCiatibn of potassium chloride in very dilute 



solui 1 s-001 molar). This was n 



