June 18, 1920] 



SCIENCE 



605 



as a teacher at a ridiculously low figure when 

 measured by his training and talent. 



He has done and is doing this under the 

 spur of that most intangible but most essen- 

 tial trait of man that we call character, and 

 because of those chimseras of the mind of 

 man that we call ideals. Is he sanely enough 

 balanced to conform his ideals to the trend 

 of the times, to the chance for subordinating 

 them to the broader plans of leadership; or 

 are ideals never ideals when his own mind 

 does not shape them, when from sport — which 

 one pays for, they become work — for which 

 one is paid? And if the zealot who can not 

 modify his view still continues in our midst, 

 as he must, is he to be weeded out ; or allowed 

 on sufferance to occupy the waste places of 

 research; or to be kept purposefully from ex- 

 termination, against a day when the nourish- 

 ing hand of society may be withdrawn, and 

 zeal in research again becomes synonymous 

 with its primal meaning — devotion with all 

 one's character to one's inborn ideal? 



As we, the professionals in science who 

 follow the amateur on to the stage, find our- 

 selves marshalled in the ranks or leading the 

 artisans of science, it may be well to remem- 

 ber that a Galileo, a ISTewton, a Berzelius and 

 a Darwin lived and worked — not in vain — 

 before the day of organization and intensive 

 team work had dawned ! 



William Teelease 



The Univeksitt of Illinois 



THE STRUCTURE OF THE HELIUM 

 ATOM 



AcccoRDiNG to the model which Bohr pro- 

 posed in 1913, the helium atom consists of 

 two electrons moving in a single circular 

 orbit having the nucleus at its center. The 

 electrons remain at the opposite ends of a 

 diameter and thus rotate in the same direc- 

 tion about the nucleus. The angular momen- 

 tum of each electron is assumed to be h/2'"', 

 where h is the quantum constant. The ion- 

 izing potential of helium calculated by this 

 theory is 28.8 volts. Recent experimental 

 determinations by Franek and Knipping have 

 given 25.4 =t 0.25 volts. Bohr's theory is 



approximately right but does not give the 

 true structure. 



For the hydrogen atom and helium ion, 

 atoms containing but a single electron, Bohr's 

 theory seems to be rig'orously correct. For 

 atoms containing more than one electron there 

 are many facts which indicate that modifica- 

 tions or extensions are needed. 



The chemical properties of the elements, 

 particularly the periodic relationships and 

 the phenomena of valence, have shown defi- 

 nitely that the electrons are not in general 

 arranged in coplanar orbits. According to 

 the theory which I advanced last year, the 

 electrons in their most stable arrangements 

 move only within certain limited regions 

 about the nucleus, each of these cells con- 

 taining not more than two electrons. The 

 atoms of the inert gases were found to have 

 their cells arranged symmetrically with re- 

 spect to an equatorial plane, no electrons how- 

 ever ever lying in this plane. According to 

 this view, the two electrons in the helium 

 atom should not move in the same orbit but 

 in separate orbits symmetrically located with 

 respect to the equatorial plane. The two 

 electrons in the hydrogen molecule (and in 

 every pair of electrons which acts as a chem- 

 ical bond between atoms) must be related to 

 one another in the same way as those of the 

 helium atom. 



The most obvious model of this type is one 

 in which the two electrons move in two cir- 

 cular orbits in parallel planes equidistant 

 from the nucleus. By properly choosing the 

 diameters of the orbits, the force of repul- 

 sion between the electrons is compensated by 

 the component of the attractive force of the 

 nucleus perpendicular to the plane. This 

 model however proves impossible as it gives a 

 negative value ( — 5.8 volts) for the ionizing 

 potential. 



A. Lande-' has recently proposed a model 

 for the eight electrons of an octet in which 

 each electron occupies a cell boimded by 

 octants of a spherical surface. The eight 

 electrons move in such a way that their 

 positions are symmetrically placed with re- 



1 Verh. d. phys. Ges., 21, 653, Oetober, 1919. 



