Ga.<es and MHuIs at Iliiih Temperatures. 03 



Mv experiments lead me to doubt conclusions drawn from 

 the apparent absence of this or that element in the spectra 

 of stars ; for there is a strong possibility that reactions enter 

 which may mask the presence of this gas or that metal. 



The conclusions of my work thus far are as follovvs : — 



1. The metallic lines due to terminals in rarefied hydrogen, 

 and rarefied air, when these terminals are one centimetre 

 apart in glass or quartz capillaries exhibit a reyersed action. 

 When this takes place it is generally coincident with the 

 position of the line when the spectrum is taken in air^ while 

 the spectrum of the line on the least refrangible side is much 

 broadened. This seems to indicate a gaseous product, an 

 oxidization or hydration due to the dissociation of the air and 

 water-yapour present. 



2. Highly heated rarefied hydrogen and rarefied air passing- 

 over containing walls of glass or amorphous silica, giye broad 

 bands which apparently coincide with narrow silicon lines of 

 far lesser intensity in air. These also T attribute to the dis- 

 sociation of air and water-yapour. The brilliancy of the 

 light produced in this reaction is far greater when there is 

 an excess of hydrogen in the tubes than when rarefied air 

 fills them. It is a question whether certain lines produced 

 by metals like silicon, which yolatilize with difiiculty in air, 

 are really due to the metals. I am inclined to attribute some 

 of them to the enyironment; that is, to a reaction between the 

 metal and the gases present. 



3. Spark-spectra of metals appear to represent complicated 

 reactions of gases with the metallic yapour. 



4. Metallic yapours carry the main portion of an electric 

 discharge when these terminals are within 3 millimetres of 

 each other in rarefied hydrogen or rarefied air. The gaseous 

 ions, if the dissociation occurs, giye little light. 



5. The broadening of the light accompanying the reversed 

 lines, if unsuspected;, might lead one to conclude that a shift 

 of the bright portion had occurred. 



6. Since the iron lines do not appear under what seem 

 favourable conditions while aluminium lines appear, while in 

 other cases gaseous lines mask metallic spectra, it seems de- 

 sirable to be cautious in regard to speculations respecting 

 types of stars. 



7. Whatever may be the cause of the reversals of lines 

 observed in narrow capillaries of glass or of quartz, it seems 

 to me that it is a fact which should be reckoned with in 

 photographic study of stars, especially in the case of sudden 

 changes of light. 



Jetterson Physical Laboratory, 

 Harvard University. 



