256 78 



In other respects the measurements of argon and helium-neon show con- 

 siderable harmony in gas samples from the same spring group, and tliis may be 

 considered as a guarantee of the accuracy of the methods employed. 



Table VI shows that the relation between the argon and the nitrogen con- 

 tained in the spring gases is fairly constant in the samples from Reykir, Laugaras, 

 Grafarbakki and Hveravellir, and in the sample Reykjafoss No. 1, being in each 

 case a little greater than in the atmosphère. 



I have already shown that it is probable that the nitrogen contained in the 

 gas samples from Hveravellir and Reykjafoss No. 1 is of atmospheric origin ; one 

 is, therefore, well within the bounds of reason in concluding that in the spring 

 gases from Reykir, Grafarbakki and Laugaras it is also of atmospheric origin. The 

 surplus of argon in the spring gases may therefore be ascribed partly to the 

 greater absorption of argon in water, and partly to the destruction of nitrogen in 

 the soil. 



The fluctuations in the amount of helium-neon in the spring gases are much 

 less than I had expected. One can hardly form a true conception of the amount 

 of helium in the spring gases from the table, for the proportion between the helium 

 and neon varies considerably. For instance, the spectroscopic examination of the 

 helium-neon mixtures from Reykir, Laugaras and Grafarbakki showed a fairly in- 

 tense spectrum of neon as compared with the spectrum due to helium, while no 

 lines due to neon were visible in the spectrum of Hengill No. \. The fluctuations 

 in the amount of helium are doubtless much greater, therefore, than Table VI 

 shows. On the other hand the measurements do not indicate any parallel between 

 the amount of radium emanation and helium. 



I have also endeavoured to trace xenon and krypton in argon gas from the 

 spring gases. For this purpose I used the same apparatus as for the separation of 

 the helium-neon from the argon, but in this case I cooled the charcoal to — 80° C. 

 by means of liquid carbon dioxide. As Valentiner and Schmidt' have shown, it 

 is possible in this way to detect xenon and krypton in argon, the xenon and 

 krypton being retained by the cold charcoal, while the argon is removed by means 

 of the pump. As I expected to find only minute quantities of these gases, I mixed 

 together all the argon that originated from the same spring group, before examining 

 it. But 1 was unable to detect any trace of these rare gases. I then mixed the 

 last distillates of the argon gases from Reykir, Laugaras and Grafarbakki, and 

 examined this gas mixture in the above- described manner for xenon and krypton, 

 but without success. If, therefore, the spring gases contain any xenon or krypton, 

 it must be in very small quantities. 



Thus the study of the rare inert gases has not given a decisive answer as to 

 the origin of nitrogen in the Icelandic spring gases, but it is most probable that 

 the nitrogen found in springs such as those at Reykir, Laugaras and Grafarbakki, 

 which are rich in nitrogen, is chiefly of atmospheric origin; while the small quan- 



' Ann. d. Phys. IV Folge. 18, 187. 1905. 



