﻿in the Emission of Positive Thermions from Salts. 141 



examined spectroscopically. An electrodeless discharge was 



established through the gas between strips of lead foil which 

 encircled the capillary at points four or five centimetres 

 apart. An induction-coil was employed in exciting the 

 discharge, and the wave-lengths of the emitted light were 

 determined by means of a Hilger direct-reading spectrometer. 

 The lines observed appear in the left-hand column of the 

 following 1 table : — 



Lines 

 observed. 



Hg* 



615 



cot. 



Lines 

 observed. 



Hg* 



cot. 







519 





519 



606 





607 





495 





579 



578 





482 





483 



568 



568 





450 





450 



560 



559 



560 



435 



436 





546 



i 



545 











* Watts. 



t Hagenbach & Ivonen. 



Comparing these wave-lengths with those given in the 

 second and third columns it is evident that at least a part of 

 the evolved gas was carbon monoxide, as in Horton's experi- 

 ments, or carbon dioxide, since this gas splits up in a discharge- 

 tube and gives the carbon monoxide spectrum. 



The apparatus was not, in the present case, free from 

 grease and other possible sources of organic matter, and it 

 was, therefore, necessary in order to determine if the carbon 

 monoxide came actually from the salt to carry out a blank 

 experiment. For this purpose the strontium chloride was 

 removed from the strip by means of distilled water and the 

 experiment repeated. The evolution of gas was at first as 

 large as before. After a short time, however, the difference 

 in pressure when the strip was heated and when it was not 

 began to decrease, and finally became immeasurably small. 



Before running this blank experiment, and while the 

 strontium chloride was apparently evolving considerable 

 quantities of carbon monoxide, several determinations were 

 made of the specific charge of the ions. The observed values, 

 although somewhat low, are taken to indicate an emission of 

 strontium atoms minus single electronic charges. Five 

 determinations gave the values 96, 93, 91, 92, and 92. One- 

 half the electrolytic value of ejm for strontium is 111, while 

 the values of e/m for carbon monoxide and carbon dioxide 

 molecules carrying single positive charges are 348 and 243 

 respectively. It seems evident, therefore, that although the 



