PHYSICS — KING, LEWIS. 253 



King:, Atthut S.f University of California, Berkeley, California. 

 Grant No. 164. Prod7idw?i and study of emission spectra at high 

 temperatures. $1,000. 



Report. — During the past year Dr. King has been engaged in exper- 

 iments extending and confirming the results noted in his first report; 

 also in an investigation of the argon spectrum in vacuum tubes and 

 in the preparation of the English edition of the ' 'Atlas of emission 

 spectra," by Hagenbach and Konen. 



The further work with electric ovens at the University of Bonn 

 showed the usefulness of the method in obtaining the spectra of a 

 large number of substances through the agency of temperature alone, 

 many differences being noted in these spectra as compared with those 

 given by the flame, arc, and spark ; the shift of maximum of radi- 

 ation in the caesium series with varying temperature was confirmed, 

 and groups of bands discovered in the spectra of calcium, strontium, 

 barium, and copper, which are not brought out by the usual methods. 

 The applicability of the oven in the study of absorption spectra was 

 also demonstrated. The work is being continued in the University 

 of California with the entire apparatus inclosed in a vacuum chamber. 



In the University of Berlin the conditions were investigated under 

 which the very small quantity of argon in ordinary air can be made 

 to show its spectrum. The results of other observers had shown 

 quite unusual conditions to be required for the appearance of this spec- 

 trum. A series of experiments by the writer showed the necessary 

 condition to be a very high momentary value of the current intensity, 

 such as is given by the conditions of the oscillating discharge. When 

 this condition was present, the argon spectrum appeared distinctly 

 in vacuum tubes containing air at various pressures, and even in the 

 open air with the spark between metallic electrodes. 

 Lewis, E. Percival, University of California, Berkeley, California. 

 Grant No. 1 50. Photographic investigations of vacuum-tube spectra 

 of gases and vapors. (For first report see Year Book No. 3, 

 p. 128.) $500- 



The large quartz prisms ordered by Professor Lewis from A. Jobin, 

 Paris, were not furnished until March of the present year, on account 

 of the difiiculty of finding large specimens of quartz. During the 

 summer the lenses and prisms in a spectrograph of rough construc- 

 tion were tested, in order to determine the best permanent form to 

 adopt. After the completion of the plans a mechanic took charge 

 of the construction, which is now well under way. The spectro- 

 graph will be the largest and most efficient of its kind yet constructed, 

 and it is hoped that the next report will present a satisfactory 

 account of research work accomplished by its aid. 



