February 14, 1918J 



NATURE 



473 



In the study of the chemical actions, involved in the ' 

 dissolution of gold by sodium cyanide solutions it is 

 necessary to know the extent of the hydrolysis of the 

 latter, because it has been shown that this is an impor- 

 tant factor in the, rate of dissolution. An ingenious 

 method for the estimation of the degree of hydrolysis 

 r sodium cyanide solutions has been devised by 

 Icssrs. F. P. Worley and V. R. Browne (Chemical 

 society's Journal for December). A set of three flasks 

 and three test tubes is set up in such a way that a 

 current of air can be aspirated through all six vessels, 

 tl?e flasks alternating with the test-tubes. The latter 

 contain an alkaline solution of sodium picrate ; the 

 first flask contains hydrocyanic acid of one concentra- 

 tion, the second the sodium cyanide solution, and the 

 third hydrocyanic acid of a second concentration. The 

 'Icpth of the reddish-brown colour produced in the 

 icrate indicator solution depends on the concentration 

 .1 hydrogen cyanide vapour in the air current. Conse- 

 quently, by varying the concentration of the hydro- 

 cyanic acid solutions until one is found which gives 

 the same intensity of colour as the sodium cyanide 

 solution, the concentration of hydrocyanic acid which 

 lias the same hydrogen cyanide pressure as the sodium 

 rvanide solution is determined. It was shown that 

 tile amount of hydrogen cyanide removed from solution 

 is too small to affect the degree of hydrolysis, and that 

 the whole of the vapour was absorbed by one tube of 

 picrate solution. 



Messrs. W. O. Robinson, L. A. Steinkoenig, and 

 I . F. Miller have analysed the ashes of a large number 

 if legumes, vegetables, grasses, trees, and bushes to 

 determine whether the rare elements which have been 

 found in certain soils occur in plants which have been 

 grown on those soils. The results, together with 

 analvses of the soils in question, are published in Bulle- 

 tin No. 600 of the U.S. Department of Agriculture. 

 Spectroscopic quantities of lithium were found in all 

 the plants examined, and rubidium was present in the 

 majoritv of cases, the quantity of it being larger than 

 that of other rare alkalis. But plants containing 

 001 per cent, or more of rubidium oxide had been 

 grown on soil in which rare alkali minerals are known 

 to occur. Caesium was detected in the ashes of 

 timothy grass from Mount Mica, Paris, Me., the red 

 raspberry from Beryl Mountain, Acworth, N.H., and 

 the beets from Marlboro, N.H. Caesium beryls have 

 been found in the first two of these localities. Molyb- 

 denum was never detected; chromium and vanadium 

 were occasionally found, though only in traces. Deter- 

 minable amounts of barium were found in the ash of 

 all the plants examined, and strontium in all except 

 bean" seeds. Very small quantities of titanium were 

 present in the ash of all the plants. All the plant 

 ashes analysed, except two, contained aluminium. 

 Pine needles contain an exceptionally high amount of 

 the latter element. The larger the amount of rubi- 

 dium and caesium, but not of lithium, present in the 

 soil, the more is absorbed by the plant. There is no 

 evidence that vanadium replaces phosphorus (as phos- 

 phoric acid) in its functions in the plant. The authors 

 conclude that of the elements determined none need 

 be considered in fertiliser practice except those corn- 

 monly used, and sulphur, chlorine, and manganese in 

 some cases. The appendix to the bulletin contains a 

 detailed account of the analytical methods employed. 



Messrs. H. Sotheran and Co., 140 Strand, have 

 just issued a catalogue (No. 770) of rare and standard 

 books on exact and applied science, which is of excep- 

 tional interest and value. It includes the scientific por- 

 tion of thelibrarv of the late Lord Justice Stirling, and 

 selections from the collections of George Rennie, 

 F.R.S.. Samuel Roberts, F.R.S., and other men of 

 NO. 2520, VOL. 100] 



science, and gives' particulars of a large number of ver> 

 scarce works. The list is particularly strong in sets of 

 journals of scientific societies. Among many rare 

 volumes we notice the following : — The first edition of 

 the Opus Majus of Roger Bacon; the Ediziorie 

 Nazionale of Galileo's works; Borgo's •' Libro de 

 Abacho" (the first edition of the first printed treatise 

 on arithmetic) ; the first Continental edition of Napier's- 

 ■' Logarithmorum Canonis Descriptio," etc. ; the first 

 edition of Gilbert's '' De Magnete, Magneticisque Cor- 

 poribus, et de Magno Magnete Tellure, etc." ; the first 

 octavo edition of Newton's "Opticks," with MS. addi- 

 tions and corrections jn Sir Isaac Newton's handwrit- 

 ing ; and Dalton's "New System of Chemical Philo- 

 sophy," complete. The catalogue is published at 

 2s. 6d. net. 



OUR ASTRONOMICAL COLUMN. 



G.^LACTic Co-ordinates. — An interesting article on 

 the galactic circle as a plane of reference for star 

 places is contributed to the February number of 

 Scientia by Dr. A. C. D. Crommelin. Following a 

 comparison of the more familiar systems of co- 

 ordinates, it is explained that catalogues of stars giving 

 positions with respect to a plane which is independent 

 of the earth's motions would have the great advantage 

 that they would not get out of date as our present 

 catalogues do, as only small corrections for proper 

 motion would be required. The most obvious' circle of 

 reference is that provided by the Galaxy, for almost 

 every feature either of distribution or of motion of 

 the various classes of stars is based on the Galaxy as a 

 plane of symmetry. It is difficult to give precision to 

 the definition of the galactic circle, but from a con- 

 sideration of eight determinations. Dr. Crommelin sug- 

 gests that the adopted position of the north galactic 

 pole, for the equinox of 1900, should be R.A. i2h. 42m. 

 37s., decl. +27° 32'. It is further suggested that an 

 actual star should be selected to mark the zero of 

 galactic longitude, say a Cygni, which has an extremely 

 small proper motion. The general adoption of some 

 such scheme has been widely advocated, and will doubt- 

 less sooner or later be realised. 



Molecular Scattering of Light. — In a paper com- 

 municated to the Astronomical Society of France 

 (L' Astronomic, January), Prof. Ch. Fabry gives an 

 account of Lord Rayleigh's explanation of the blue 

 coloration of the sky, and announces that the theory 

 has been experimentally verified in his laboratory at 

 Marseilles by M. Cabannes. Prof. Fabry suggests" 

 that several hitherto mysterious phenomena in the 

 heavens may possibly be explained as effects of this 

 scattering of light by gaseous molecules. In the case 

 of the solar corona, for example, the portion of the 

 luminosity which gives a continuous spectrum does not 

 necessarily imply the presence of solid or liquid par- 

 ticles, but may be attributed to the diffusion of photo- 

 spheric light by molecules of truly gaseous coronal 

 matter. A density of only one-thousand-millionth 

 part of that of atmospheric air would suffice to account 

 for the observed intensity of the coronal light, and the 

 polarisation of the light would be simply explained, as 

 in the case of the light of the sky. A part of the 

 luminosity of the tails of comets may be explained in a 

 similar manner, and in this case the density must be 

 less than one milligram per 1000 cubic metres, as other- 

 wise the luminosity would be greater than any which 

 has ever been observed. Other possible effects of mole- 

 cular scattering are also suggested. It may be added 

 that Prof. R. j. Strutt has also succeeded in observing 

 the scattering of light by dust-free air in a laboratory 

 experiment with artificial illumination (N.atlre, Octo- 

 ber 25, 1917). 



