52 



NATURE 



[March 21, 19 18 



He reviews the more important results obtained since 

 the publication of Zeeman's monograph upon the sub- 

 ject in 1912. Amongst the improvements in technique 

 have been the introduction of the Wehnelt cathode 

 lamp devised iby Dr. Mohammad himself, the use of 

 crossed spectra from two pieces of apparatus of high 

 resolving power, and the construction of more powerful 

 electromagnets. Nagaoka and Takamine have taken 

 up the study of the Zeeman effect in the ultra-violet 

 region, whilst Croze has extended his observations into 

 the infra-red so far as the photographic methods allow. 

 The effect of a magnetic field on the satellites of com- 

 plex lines is likely to give a clue as to the mechanism 

 of radiation and the production of spectrum lines. The 

 study of the magnetic resolution of band spectra has 

 attracted much attention. There is now no doubt of 

 the fact that some band spectra show the Zeeman 

 effect, but opinion is divided as to the existence of the 

 effect in otiier cases. Certain dissymmetries have been 

 observed both in the place and in the position of com- 

 ponents, and several complicated types of magnetic 

 resolution have been noticed. Anomalies of a different 

 kind have been found in which the lines of a very 

 close doublet or triplet series appear to influence each 

 other in a peculiar manner. On the theoretical side 

 Voigt has modified and extended the theory of Lorentz, 

 introducing into the equations terms expressing a re- 

 sistance, a quasi-elastic force, and allowing for the 

 coupling of the electrons. It is to be noted that when 

 the quantum hypothesis, as rqjresented by Bohr's equa- 

 tions, is assumed, there is no place left for the quasi- 

 elastic oscillating electrons which have been used in all 

 theories for the explanation of the Zeeman effect from 

 Lorentz to Voigt. 



Now that our rations of food, particularly of meat 

 and wheaten bread, have been so appreciably reduced 

 the necessity of arranging our diet so as to ensure a 

 sufficient supply of those elusive substances, the so- 

 called "vitamines," is more important than ever. It is 

 known that these substances exist in certain foods, and 

 that an adequate supply of them is necessary to health, 

 but they have not yet been isolated in a pure condition, 

 although several workers claim to have done so suc- 

 cessfully. As a result of some recent work, McCollum 

 and Davis concluded that two distinct types of vitamine 

 exist, the " fat-solu.ble A" and the "water-soluble B." 

 In the Biochemical Journal for December Mr. J. C. 

 Drummond describes yet another attempt to isolate the 

 latter type of accessory substance. Unfortunately the 

 attempt failed, but several interesting observations 

 were made. In Mr. Drummond's experiments pure- 

 bred rats were fed on a basal artificial diet containing 

 all the necessary constituents except the water-soluble, 

 growth-promoting accessory substance, and also on the 

 same diet together with marmite which had been 

 treated in various ways. From the variation of the 

 live weight of the rats the "presence or absence of the 

 "water-soluble B " in the treated marmite is inferred. 

 In this way it is established that the water-soluble 

 accessory substance is (i) soluble in 70 per cent, alcohol, 

 but insoluble in absolute alcohol ; (2) dialysable through 

 parchment paper; (3) injured by heating at 120°, but 

 very little affected at 100°; (4) largely destroyed by 

 prolonged boiling with 20 per cent, sulphuric acid, but 

 not with I per cent, hydrochloric acid ; and (5) much 

 damaged by digestion with hot 5 per cent, sodium 

 hydroxide, but very little affected by the same solution 

 cold. Water solutions containing the active substance 

 give voluminous precipitates with phosphotungstic acid, 

 basic lead acetate, and silver nitrate, but the solutions 

 recovered from these precipitates by the customary 

 methods have little activity. The author attributes this 

 fact to loss of the substance by adsorption rather than 

 to its actual destruction. The results support the view 

 NO. 2525, VOL. lOl] 



that the so-called "antineuritic vitamine" is identical 

 with the "water-soluble B." 



Mr. F. Edwards, 83 High Street, Marylebone, has 

 just published a catalogue (No. 381) of books on 

 British and foreign birds. It contains some 642 titles. 

 Some of the books are scarce. Two sets of the Ibis 

 (1859-1915) are offered for sale. 



Messrs. Gauthier-Villars et Cie (Paris) announce 

 the following science books :— Oiuvres de Henri Poin- 

 car6 publi6es sous les auspices du Ministere de J 'In- 

 struction publique par G. Darboux, tome i. ; Qiuvres' 

 de G. H. Halphen publi^es par les soins de C. Jordan, 

 H. Poincar^, E. Picard, avec la collaboration de E. 

 Vessiot, quatre vols., tomes ii., iii., et iv. ; Cours de 

 G^om^trie pure et appliqu^e de I'Ecole Polytechnique, 

 Prof. M. d'Ocagne, tome ii., Cin^matique applicju^e, 

 St6r6otomie, Statique graphique; Calcul graphique, 

 Calcul grapho-m^canique, Nomographie. 



OUR ASTRONOMICAL COLUMN. 



The Planet Mars. — ^This planet came to opposition 

 with the sun on the m^orning of March 15. On that 

 date Mars was about sixty-one million miles distant 

 from the earth, and had an apparent diameter of a 

 little more than fourteen seconds of arc. The planet 

 is now situated in Leo, on the eastern border, and 

 moving to the W.N.W. 



The present opposition of the planet is by no ineans 

 a favourable one for the study of his surface marl^ings. 

 It is curious, however, that some excellent views of the 

 markings have been obtained on occasions when the 

 disc was comparat"vely small, and when little success 

 in this direction was expected. The fact is that certain 

 lineaments on Mars, such as the Syrtis Major, the Mare 

 Sirenum, Cimmerium, and Acidalium, are so con- 

 spicuously dark and large that a very small telescope 

 is sufficient to show them, and they may be viewed 

 even when the conditions are not altogether favourable. 



Perhaps the features on Mars are, however, scarcely 

 so easily discerned as those on Jupiter, owing to the 

 expansive disc of the latter object. But the study of 

 Martian markings is more interesting from the fact that 

 they represent objects existing on its actual surface, 

 while Jovian details are merely temporary, outside 

 formations of atmospheric character. 



The double canals on Mars are now justly regarded 

 as one of the observational romances of astronomy. 

 The single canals have even been assailed as non- 

 existent, but there is no question whatever that a 

 series of linear formations is scattered over the equa- 

 torial and south-equatorial regions of the disc. Scep- 

 ticism was aroused by the hard, dark, and straight lines 

 by which some observers erroneously represented the 

 delicate streaks of shading which really diversify the 

 planet's surface, and certainly look nothing like water 

 channels to an unimaginative observer. 



It is to be hoped that the renewed study of the topo- 

 graphy of Mars will be successfully made at this opposi- 

 tion, and the revised rotation period of 24h. 37m. 

 22-57S. tested by fresh data. 



Wolf's Nova. — Besides the interesting planet found 

 in January, Prof. Wolf also discovered a Nova in 

 Monoceros. The Harvard plates have enabled its pre- 

 vious history to be traced. It was fainter than 

 98 mag. on December 22, rising to 5-4 by January i 

 (being thus the brightest Nova since 19 12). It de- 

 clined rapidly, reaching mag. 8-9 on February 4, 90 

 on February 17, 9-1 on February 22. It is 10° north 

 and 2° west of Sirius, and, like most Nov«, lies within 

 the Galactic Zone. 



Dr. Mundler gives the position for 1918-0 as R.A. 

 7h. 22m. 47-oos., S. declination 6° 30' 34-7". 



