February 26, 1920] 



NATURE 



715 



February 2. — Sir George A. Berrv, vice-president, 

 in the chair.— Dr. C. G. Knott and Miss Dallas: 

 Magnetic strains in nickel-steel tubes. The material 

 was the usual commercial nickel-steel with 2-63 per 

 cent, of nickel. The four tubes were cut down from 

 the same bar, being all of equal length and equal width, 

 and the bores were J', \, |, and i in. in diameter. 

 The changes in the length of each tube in various 

 fields were measured, as were also the corresponding 

 changes in volume of the bore of the material and 

 in the external form when the bores were plugged 

 so that the tubes were in appearance solid cylinders ; 

 and from these measurements the values of the several 

 linear dilatations in these fields were calculated. The 

 longitudinal dilatation was always positive, attaining 

 a value of from 3-5x10-'' to nearly 5x10-' in field 

 500. The corresponding radial and tangential dilata- 

 tions were negative, and ranged from —1-3x10-' to 



— 2-4X 10" 



The results indicate that a spherical 



element becomes ellipsoidal or spheroidal, with the 

 longest axis along the axis of the tube. If the 

 effect is" to be explained in terms of the orientation 

 of magnetic molecules, then these molecules tend to 

 set with their longer axes along the lines of magnetisa- 

 tion. In former experiments with iron and steel the 

 longitudinal dilatation changed sign from positive to 

 negative in fields of about 300 to 400. In nickel, 

 again, the lonsjitudinal dilatation was alwavs negative 

 and about eight or ten times larger than in the case 

 of either iron or steel. In nickel-steel the dilatation 

 remained positive up to the highest fields used (about 

 qoo), although in three of the tubes it passed its maxi- 

 mum in field 400 or 500. So far as magnetic strains 

 are concerned, the small admixture of nickel does not 

 impart to the allov anv nickel characteristic whatever. 

 — Prof. W. Peddle : The adequacy of the Young- 

 Helmholtz theorv of colour-vision and colour-blindness. 

 Trichromasv in normal eves is not now theoretical, but 

 a proved fact. Hering's theory, which is favoured 

 bv some investigators, is, as Helmholtz showed, also 

 a trichromatic theorv ; and while both can account for 

 the observed facts, the Young-Helmholtz theory is the 

 simplest that can be formulated. Lack of rec0£?ni- 

 tion of its accuracv has been due to non-recognition 

 of the fact of normal trichromasy ; or to the erroneous 

 supposition that it is tied down to anv one definite 

 view of the nature of the physical and physiological 

 actions concerned in vision ; or to the equally 

 erroneous supposition that it can account for onlv one 

 particular tvpe of colour-blindness with merely in- 

 dividual variations. It can account for any type that 

 is known, or for any at present unknown which 

 mav afterwards be found to exist, provided onlv that 

 it arises from limitation of the at present known 

 normal conditions. — Prof. W. Peddle ; Note on the 

 quaternionic svstem as the algebra of the relations of 

 phvsics and relntivitv. The author showed that in all 

 cases in which our observations are upon directed 

 phenomena occurring' in tridimensional space, but 

 which are actually or merely descriptively to be re- 

 garded as influenced bv the existence of that space 

 in space of a higher order, the appropriate algebra to 

 be used in their investigation is that of Quaternions 

 with the addition of the symbol of the space involved. 



Paris. 

 Academy of Sciences, February 2. — M. Henri 

 Deslandres in the chair. — The president announced 

 the death of Jules Boulvin, correspondant of the 

 Academy. — C. Moureu and G. Mlgnonac : The de- 

 hvdrogenation of the primary and secondary alcohols 

 bv catalytic oxidation. .A general method of prepara- 

 tion of aldehydes and ketones. Finely divided silver 

 deposited on asbestos was found to be the best 

 NO. 2626, VOL. 104] 



catalyst, and the oxidation is carried out in stages, 

 only about half the amount of air theoretically 

 required for the full reaction being employed in the 

 first stage. The results for nine alcohols are given ; 

 the yields are high — 62 per cent, for formaldehyde and 

 70 to 95 per cent, for the higher aldehydes.— A. 

 Gautler : The normal arsenic in living tissues and 

 the traces of iodine found in air and waters. Some 

 necessary corrections.— G. .\. Boulenger : An extra- 

 ordinary tortoise, Testudo Loveridgii. This tortoise 

 is the first example of a reptile in the adult state 

 without ribs, and is a unique case of normal osteo- 

 lysis.— M. Chodat was elected a correspondant for 

 the section of botany in succession to M. Flauhault, 

 elected non-resident "member, and M. Ch. Nicolle a 

 correspondant in the section of medicine and surgery 

 in succession to the late M. Lupine.— L. de Peslouan : 

 .\ congruence between Bernoulli's numbers. — P. Idrac : 

 Study of hovering flight in Upper Guinea.— M. 

 Romieux : Alluvial strata of the Lot in the neigh- 

 bourhood of Fumel.— L. Brillouln : The continuous 

 spectrum of X-rays.— F. Canac : The determination 

 of the axes of symmetry of a cubic crystal. — R. 

 Abrard : A Mesolia'ssic fauna of Sidi Mouley Yakoub 

 (Western Morocco).— F. La Porte : Atmospheric 

 observations at Gavre by means of free rubber balloons. 

 The experimental results can be fairly well repre- 

 sented by Dines 's formula with a modified numerical 



constant, V= ;^^^, where V is the ascensional 



velocity per minute, F the ascensional force, and P 

 the weight of the envelope in grams.— L. Emberger : 

 The evolution of the chondriome in the vascular 

 Cryptogams. — L. Daniel : Antagonistic reactions and 

 role of the pad in grafted plants.— M. Bezssonofl : 

 Experimental sexuality in fungi, situated on the 

 typical structure of the sexual plasma.— F. Gard : 

 Division in Euglena limosa.—G. Andr6 : The inver- 

 sion of saccharose in the juice of the orange.— E. 

 Hirouard : Double monsters of the scyphistome.— C. 

 Gessard : Pvocvancid bacilli. 



BOOKS RECEIVED. 



The Topographical Anatomy of the Limbs of the 

 Horse. By Dr. O. C. Bradley. Pp. xi-t-i72. (Edin- 

 burgh : W. Green and Son, Ltd.) 



Harmsworth's Universal Encyclopedia. No. i. 

 Pp. xix+128. (London: The Amalgamated Press, 

 Ltd.) IS. 3i. . , 



Index of Economic Material in Documents of the 

 States of the United States. Pennsylvania, 1790- 

 1904. Part i. By A. R. Hasse. Pp. 810. (Washing- 

 ton : Carnegie Institution of Washington.) 



Index to U.S. Documents relating to Foreign 

 Affairs. 1828-1861. In three parts. Part ii. By 

 A. R. Hasse. Pp. 795-1331. (Washington : Car- 

 nefie Institution of Washington.) 



British Journal Photographic Alman.-ic and Photo- 

 grapher's Daily Companion, iq20. Edited by G. E. 

 Brown. Pp. 912. (London : H. Greenwood and Co., 

 Ltd.) IS. 6d. net. 



A Field and Laboratory Guide in Physical Nature- 

 Study. Bv Prof. E. R. Downing. Pp. 109. (Chicaeo : 

 University of Chicago Press ; London : Cambridge 

 University Press.) i dollar net. 



Practical Pharmacology : For the Use of Students 

 of Medicine. Bv Prof. W. E. Dixon. Pp. yiii + 88. 

 (Cambridge : At' the University Press.) 7^. 6d. net. 



Chemistry for Textile Students. By B. North. 

 .Assisted by N. Bland. Pp. viii + 379. (Cambridge: 

 .'\t the University Press.) 30.?. net. 



.'Vn Introduction to the Study of Cytology. By 

 Prof. L. Doncaster. Pp. xiv4-28o + xxiv. (Cam- 

 bridge: .At the University Press.) 2 is. net. 



