V..] 



CHEMISTRY OF THE STARS. 



kited, the only difference in the employment of the formula being that 

 even values of n were used instead of odd values.* 



Professors Pickering and Kayser both concede that this new form 

 of hydrogen is due most probably to a high temperature, and Professor 

 Kayser expressly states "that this series has never been observed 

 before can perhaps be explained by insufficient temperature in our 

 Geissler tubes and most of the stars." 



If, as suggested both by Professor Kayser arid myself, this new 

 series and the one previously known are probably of the subordinate 

 type, the principal series of hydrogen is still beyond our ken, unless 

 indeed one of the still " unknown " lines represents it, as suggested 

 by Professor Eydberg. Another possibility is that, even in the hottest 

 stars so far considered, the temperature is not high enough to allow 

 its molecule to exist uncombined. 



On the view that the new series of probable hydrogen lines in 

 Puppis represents the effect of a transcendental temperature, an 

 attempt has been made to produce this spectrum in the laboratory. 

 In the high-tension spark in hydrogen at atmospheric pressure the 

 ordinary series is represented by broad lines. The use of the spark 

 with large jars in vacuum tubes results in the partial fusion of the 

 glass and the appearance of lines which have been traced to silicium, 

 but the new series has not yet been observed. 



In his first communication Professor Pickering mentions lines at 

 4698, 4652, 4620, and 4505, but he does not refer to them in his- 

 second paper, which has special reference to the new series. The line 

 4505 was at first taken to be one of the components of the new series,, 

 but this seems to have been subsequently superseded by the employ- 

 ment of the line about 4544, which agrees better both as regards- 

 intensity and the calculated position 4543'6. 



* The two series are as follows : 

 Old Series. 



New Series. 



These figures are taken from Professor Pickering's article in Astrophysical 

 Journal, vol. v, p. 93. See also Kayser's article on p. 95 of the same journal. 



