548 



NA TURE 



[September 27, 1906 



In the Zcitschrift fur Elektrochemic (vol. xii., p. 513) 

 Prof. W. Kistiakowsky points out the existence of a 

 relationship between the surface-tension values of different 

 liquids which is analogous to the well-known Trouton's 

 rule. If k denote the capillary constant of a_liquid at its 

 boiling point, m the molecular weight, and T the boiling 

 point on the absolute scale, then mfe/T is constant and 

 equal to 001 16 for about forty non-associated liquids which 

 have been examined. In the case of associated liquids, 

 such as the alcohols and fatty acids, the value of mfc/T 

 is much smaller, and on account of the considerable 

 change in the value of the factor it appears to be eminently 

 suited for ascertaining the existence of association in the 

 liquid state of aggregation. 



The report of the principal chemist of the Government 

 Laboratory for the year ending March 31 furnishes some 

 interesting reading. The total number of samples examined 

 at the laboratory at Clement's Inn Passage during the 

 year was 106,779, the greater part being in connection 

 with the revenue departments. In the Customs the in- 

 crease in the number of samples examined, as compared 

 with last year, was 2389, the Excise showing an increase 

 of more than 18,000. Special attention was given to 

 establishing a systematic check on the " obscuration " of 

 enumerated spirits, that is, the change • in the apparent 

 strength of spirits, as determined by the hydrometer, 

 caused by the presence of solid matters in solution. It 

 is noteworthy that, in the case of tea, the evidence of 

 deliberate adulteration was extremely rare. A small pro- 

 portion of the tea entering the country was declared 

 to be unsound and unfit for human consumption. Such 

 condemned tea does not pay duty, and, after being 

 denatured by the addition of lime and asafoetida, is allowed 

 to be used in the manufacture of caffeine. Little improve- 

 ment is shown in the freedom from adulteration of the 

 beer supplied by publicans; ii-i per cent, of the samples 

 taken were found to be diluted. There is good reason, 

 moreover, to believe that a notable amount of butter 

 adulteration takes place in this country. A considerable 

 increase is shown in the quantity of duty-free spirit used 

 in colleges for purposes of research. 



Since the atomic weight of silver is the basis upon which 

 most of the atomic weights of other elements are founded, 

 even a small change in the accepted value is not without 

 importance. The Compics rcndus for September 10 con- 

 tains a note on this subject by P. A. Guye and G. Ter- 

 Gazarian. Owing to the great improvements in recent 

 years in the methods of dealing with gases, physico- 

 chemical methods of determining atomic weights, originally 

 only used as a rough guide for the purely chemical methods, 

 have reached an accuracy at least equalling the latter. If 

 the atomic weights of carbon, hydrogen, nitrogen, and 

 chlorine related directly to oxygen by physicochemical 

 methods be taken as a basis, the value 107-89 is obtained 

 for silver instead of 107-93, obtained by Stas by the use 

 of chlorates, bromates, and iodates. The authors give a 

 summary of the work done by various workers on the 

 latter compounds, and note a possible cause of error in 

 the presence of potassium chloride in the potassium chlorate 

 used. They show that these two compounds, on account 

 of the fact that the chloride forms a solid solution of 

 nearly constant composition, are very difficult to separate. 

 They find that potassium chlorate, purified as far as 

 possible by re-crystallisation, contains 2-7 parts of chloride 

 per 10,000. Applying this correction to Stas's figures, an 

 atomic weight of 107-89 is obtained, nearly identical with 

 NO. 1926, VOL. 74] 



the figures of Marignac in the analysis of silver chlorate ; of 

 Dixon and Edgar, by the direct determination of the ratio 

 H : CI ; and of Richards and Wells, the ratio Ag : AgCl. 

 In this way the results of the chemical and physico- 

 chemical methods are brought into agreement, leading to 

 the conclusion that the atomic weight of silver should be 

 lowered from 107-93 '° 107-89. 



OUR ASTRONOMICAL COLUMN. 



Astronomical Occurrences in October: — 

 Oct. 2. Pallas (mag. S'o) in opposition to the Sun. 



3. gh. 19m. Minimum of Algol (j3 Persei). 



4. I5h. 35m. 10 i6h. 52m. Moon occults |U Ceti 



(mag. 4-4). 

 6. I2h. 30m. to I5h. .2Sm. Tr;insit of Jupiter's Sat. III. 



(Ganymede). 

 9. i6h. cm. Jupiter in conjunction with Moon (Jupiter 



2' 12' N ). 

 15. \'enus. Illuminated portion of disc =0333 ; of 

 Mars =o'976. 

 18 22. Epoch of Octobernieteoiic shower (Radiant 92°-)- 15°). 

 23. iih. im. Minimum of Algol (B Persei). 



25. 6h. 49m. to 6h. 56m. Moon occults 1 Capricorni 



(mag. 4^). 

 ., igh. om. Venus at greatest brilliancy. 



26. 7h. 5oni. Minimum of Algol {$ Persei). 



,, Saturn. Major axis of outer ring =42 ' 62 ; minor 



axis =4""73- 

 29. I3h. om. Jupiter .■stationary. 



The Tot.xl Sol.ar Eclipse of J.\xu.\rv, 1907. — In a letter 

 to the Observatory (No. 374), Mr. W. T. Lynn discusses 

 the accessibility and suitability of .^ndishan as a place 

 wherefrom to observe the total eclipse of the sun which 

 will take place in January ne.xt year. This town is 

 situated to the north-east of Samarkand, in the Khanate 

 of Khokand, its approximate position being long.= 

 72° 17' E., lat. =40° 50' N. It is on the Russian Central 

 Asiatic Railway, about 170 miles south-east of Tashkent. 

 As a new line of railway runs to the latter place from 

 Orenburg, the journey from Europe should prove a com- 

 paratively straightforward one. .\ndishan lies in the fertile 

 valley of Ferghana, at the junction of the river Kara 

 Darya (a tributary of the Syr Darya) and a smaller stream, 

 so that there should be little difficulty in finding a suitable 

 observing site for the eclipse parties. The eclipse will 

 take place on January 14, 1907 (civil time), and the shadow 

 track will be very narrow, thus limiting the choice of 

 stations ; the duration of totality will be about two minutes. 

 By an obvious slip, the date is given as January 4 and 

 the duration of totality as two seconds in Mr. Lynn's 

 letter, as published in the Observatory. 



Observ.\tio.\s of Phceee in May and June, 1906. — 

 Circular 118 of the Harvard College Observatory gives the 

 positions of Phoebe, the ninth satellite of Saturn, as deter- 

 mined from six photographs obtained between May 18 and 

 June 28, with the 24-inch Bruce telescope, at Arequipa. 

 The places thus obtained are compared with those given 

 bv the ephemeris published in the Nautical Almanac for 

 1906, the differences (O-C) in R.A. and declination being 

 given. 



The Colours of Sun-spots. — In the September number 

 of the Bulletin de la Sociiti astronomique dc France 

 M. Th. Hansen, of Praesto, Denmark, states that from 

 many j-ears' observations of sun-spots he is convinced that 

 sun-spots exhibit colours proper to themselves, and not 

 merely the results of instrumental chromatism. He 

 observes that the spot nuclei are rarely, if ever, a dead 

 black, but generally are of a decided violet colour. The 

 preceding part of the spot is most often of a yellow colour, 

 whilst red is generally predominant in the " following " 

 parts, although green is also seen there. On August 11, 

 1903, a small but dazzling white facula appeared in the 

 centre of a black spot whilst M. Hansen was drawing the 

 same. Two plates showing the colours observed in the 

 large spot of November, 1003, accompany the oommuni- 



