558 SCIENCE PROGRESS 



Nyquist publishes the results of researches on the Stark effect 

 in helium and neon. 



In the October number of the Proc. Roy. Soc, Profs. Fowler 

 and Strutt communicate the results of a research showing that 

 the group of six absorption lines discovered by Sir William 

 Huggins in 1890 in the photographic spectrum of Sirius lying 

 near 3,200-3,300 A. are really of telluric origin and due to the 

 ozone of our atmosphere. The same lines appear in the spec- 

 trum of some other stars, and strongly in the spectrum of the 

 sun at low altitude. 



X-Rays. — In the Phil. Mag. for October there is a paper 

 by Prof. Barkla and Miss White on the absorption of X-rays 

 of short wave length. A theory bearing on the energetics 

 of such absorption has already been given by Prof. Barkla 

 in the Bakerian Lecture for 191 6 (see Science Progress, 

 April 191 7). But observations on the intensity of corpuscular 

 radiation from air and such substances as aluminium, water, 

 paraffin, wax, and paper show an irregularity from predicted 

 results only explainable on the assumption that the light 

 elements oxygen, carbon, aluminium emit under suitable 

 stimulus a hitherto unobserved charcterististic radiation — a 

 J radiation, harder and of shorter wave length than K radia- 

 tion. In the experiments the radiation incident on the various 

 substances tested was in most cases a primary radiation from 

 an X-ray tube, from which the more easily absorbed constitu- 

 ents had been previously eliminated ; in a few cases certain 

 characteristic radiations of the K series were used as primary 

 radiations and gave results agreeing perfectly with those 

 obtained with primary radiations direct from an X-ray tube. 

 On plotting the mass absorption coefficients in aluminium, 

 water, paper, and paraffin-wax against those in copper, the 

 curves show the characteristic "kink" so well known in 

 connection with the curves which some years ago brought 

 to light the existence of the K and L radiations. These 

 " kinks " indicate by their position the existence of J radia- 

 tions from carbon, oxygen, and aluminium whose wave lengths 

 are approximately '42 x io" 8 cm., '39 x io" 8 cm., '37 x io* 8 cm. 

 respectively. Some points of theoretical interest are also 

 dealt with in this paper. 



In the November number of the Physical Review, C. S. 

 Brainin describes experiments undertaken with the purpose 



