4i8 



NATURE 



[July 24, 1919 



3 cm. from an opening in the end covered by a sheet 

 of silver of thickness sufficient to stop the o-rays 

 completely. The zinc sulphide screen was fixed out- 

 side close to the silver plate. On introducing dried 

 oxygen or carbon dioxide into the vessel, the number 

 of scintillations fell off in amount corresponding with 

 the stopping power of the column of gas. An un- 

 expected effect was, however, noticed on introducing 

 dried air from the room. Instead of diminishing, the 

 number of scintillations was increased, and for an 

 absorption equivalent to 19 cm. of air the number 

 was about twice that observed when the air was 

 exhausted. It was clear from these results that the 

 a-particles in their passage through air gave rise 

 to long-range scintillations which appeared of about 

 the same brightness as H scintillations. This effect 

 in air was traced to the presence of nitrogen, for it 

 was shown in dry, chemically prepared nitrogen as 

 well as in air. The number of scintillations was much 

 too large to be accounted for by the presenc^of traces 

 of hydrogen or water-vapour, "for the effect observed 

 was equivalent to the number of H atoms produced 

 by the" mixture of hydrogen at 6 cm. pressure with 

 oxygen. The measurements were always made well 

 outside the range of the recoil nitrogen and oxygen 

 atoms, which we have seen are stopped by 9 cni. of 

 air. 



These swift atoms which arise from nitrogen have 

 about the same brightness and range as the H atoms 

 produced from hydrogen, and, presumably, are 

 charged hydrogen atoms. Definite information on 

 this point should be obtained by measuring the deflec- 

 tion of a pencil of these atoms in a magnetic and 

 electric field. The experiments are, however, exceed- 

 ingly difficult on account of the very small number 

 of the scintillations to be expected under the experi- 

 mental conditions. It should be mentioned that t'he 

 evidence so far obtained is ncrt sufficient to distinguish 

 definitely whether these are H atoms or atoms of 

 mass 2, 3, or 4, for the range and brightness of the 

 latter would not be very different from those shown 

 by the H atom. 



It is difficult to avoid the conclusion that these long- 

 range atoms arising from the collision of o-particles 

 with nitrogen are not nitrogen atoms, but probably 

 charged atoms of hydrogen or atoms of mass 2. If 

 this be the case, we must conclude that the nitrogen 

 atom is disintegrated under the intense forces de- 

 veloped in a close collision with swift o-particles, and 

 that the atom liberated formed a constituent part of 

 the nitrogen nucleus. It may be significant that from 

 radio-active data we should expect the nitrogen 

 nucleus of atomic mass 14 to -consist of three helium 

 nuclei of mass 4, and either two hydrogen nuclei or 

 one nucleus of mass 2. 



The effect observed in nitrogen would be accounted 

 for if the H nuclei were outriders of the main nucleus 

 of mass 12. The close approach of the a-particle 

 leads to the disruption of its bond with the central 

 nucleus, and under favourable conditions the H atom 

 would acquire a high velocity and be shot forward like 

 a free hydrogen atom. Taking into account the great 

 energy of the particle, the close collision of an 

 o-particle with a light atom seems to be the most 

 likely agency to promote its disruption. Considering 

 the enormous intensity of the forces brought into 

 play in such collisions, it is not so much a matter 

 of remark that the nitrogen atom should suffer dis- 

 integration as that the a-particle itself escapes disrup- 

 tion. The results, as a whole, suggest that if 

 a-particles or similar projectiles of still greater energy 

 were available for experiment, we might expect to 

 break down the nucleus structure of many of the 

 lighter atoms. 



NO. 2595, VOL. 103] 



UNIVERSITY AND EDUCATIONAL 

 INTELLIGENCE. 



Cambridge.— Sir J. J. Thomson, Master of Trinity 

 who recently resigned the Cavendish professorship of 

 experimental physics, has been elected into the newly 

 established professorship of physics. This professor- 

 ship IS without stipend, and will terminate with the 

 tenure of office of the first professor unless the Uni- 

 versity determines otherwise. 



The General Board of Studies has made the fol- 

 lowing appointments :— Mr. F. W. Dootson, of Trinity 

 Hall, University lecturer in chemistry; Mr. W. H. 

 Mills, fellow of Jesus College, Iniversity lecturer iri 

 organic chemistry; Mr. R. Whiddington, fellow of 

 St. John's College, University lecturer in experimental 

 physics; and Mr. S. Lees, 'late fellow of St. John's 

 College, University lecturer in thermodynamics. 



Edinburgh.— On the recommendation of the Secre- 

 tary for Scotland, the King has appointed Sir Harold 

 H. Styles to the chair of clinical surgerv. 



The following appointments by the University Court 

 have been announced :— Dr. Meakin, McGill Univer- 

 sity, to the new chair of therapeutics; Dr. F. D. 

 Boyd to the Moncrieff-.\rnott chair of clinical medi- 

 cine, vacant through the resignation of Prof. Russell ; 

 and Mr. T. P. Laird, lecturer in accounting ancl 

 business method, to become professor when the 

 ordinance for the new chair is approved. 

 _ The Court has also resolved to' proceed with addi- 

 tional buildings for anatomy, and has approved the 

 plans for a new rhcmical laboratory. 



Leeds. — The University Council has appointed lo 

 the chair of education Dr. John Strong," Rector of 

 the Royal High School, Edinburgh, since 1914. 



Prof. T. Brailsiord Robertson, formerly professor 

 of biochemistry in the I'niversity of Toronto, has been 

 appointed to succeed the late Sir Edward C. Stirling 

 as professor of physiology in the University of Ade- 

 laide, South Australia. 



The Encaenia! proceedings of the University of New 

 Brunswick in Fredericton, the capital, took place in 

 May last. They included the alumni oration delivered 

 by Prof. D. Eraser Harris, of the Dalhousie Univer- 

 sity, Halifax, N.S., who took for his subject "Science 

 and Character-building." Prof. Harris laid stress 

 upon the claims of science as giving a mental training 

 second to no other intellectual exercise. He defined 

 science as that training of the mind which is im- 

 parted by a rigorous, unbiased, and sympatheic studv 

 of Nature, demanding for its successful pursuit 

 patience, care, exactness, and a strict reverence for 

 truth, all of which qualities are essential to the 

 building up of character, which is something more 

 than being conventionally moral, since weak people 

 can be moral and some conventionally immoral people 

 have been strong characters — for instance, Csesar, 

 Nelson, and Napoleon. Character is strong without 

 being oppressive, just without being narrow, self- 

 reliant without being self-centred. Science produces 

 heroism in her workers and has had her martyrs, 

 some of whom were enumerated. Truth is what men 

 of character search for, reverence, and seek to declare, 

 and Prof. Harris gave a list of the great men of 

 science who were conspicuous in this regard, strangely 

 omitting the names of Darwin, Tyndall, and Huxley, 

 and naively asked whether it is possible to name an 

 equal number of men as eminent and as reverent in 

 literature, philosophy, or art. Prof. Harris would 



