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gas sample from Laugaràs only contained nitrogen, inert gases and methane, I mixed 

 a known volume of the same gas sample with a little atmospheric air and a suit- 

 able amount of oxygen and hydrogen in chemically equivalent proportions and 

 then exploded the gas mixture. A subsequent examination of the gas remaining 

 from the explosion showed the same result as regards the methane. Immediately 

 after this I treated an equal volume of atmospheric air in exactly the same manner, 

 without detecting the slightest trace of methane. The view that the methane found 

 in the spring gas samples is not entirely due to erroneous methods in the analysis 

 work is further confirmed by the fact that the investigation of the gas samples 

 containing methane was twice interrupted by the examination of the gas samples 

 from Reykir. In these samples I could never find any traces of methane. The 

 gas samples from the hot springs at Myvatn, on the other hand, were examined in 

 the beginning of the analysis work. When one considers that several of the gas 

 samples Investigated were proved to contain no methane, it can hardly be con- 

 tended that the methane found in the remaining samples is due to awkwardness 

 in collecting the gas, or in fusing the collecting bottle. 



On the other hand, the method I employed is under a disadvantage, as com- 

 pared with that used by Bunsen, in that the gas under investigation often comes 

 into contact with organic substances, the indiarubber tubing, and the grease on 

 the stop-cocks. It is therefore, in my opinion, more probable that where very 

 small quantities of methane are found, — i. e. only a few thousandths of the entire 

 volume of the gas examined, — it is on account of erroneous treatment of the gas 

 sample, rather than that methane is really a constituent of the original spring gas. 

 But where methane is found in larger quantities as, for instance, in the gas 

 samples from Hveravellir, I consider it quite impossible that this should be due 

 exclusively to errors in analysis. In these cases methane is really contained in 

 the spring gases. 



The existence of methane may be explained as follows. The spring water, 

 or at least a part of it, comes from swampy ground, and it is a well-known fact 

 that methane is produced in such places by fermentative processes in organic 

 matter. In this way the water conveys the methane to the interior of the earth, 

 where it is mingled with the other spring gases. 



Three of the gas samples from Reykjafoss are, as regards their composition, 

 most closely allied to the class of spring gases represented by the gas samples 

 from Hengill, Kerlingarfjöll and Krafla. But this might have been expected, for 

 the hot springs at Reykjafoss and Hengill may really be considered as one group 

 of hot springs, which stretches from Reykjafoss right through to Hengill. The 

 small quantity of nitrogen found in the spring gases from Reykjafoss indicates 

 that they are only slightly mixed with atmospheric nitrogen and other gases of 

 atmospheric origin. The amount of hydrogen gas and, to some extent, of 

 sulphuretted hydrogen, is less than at Hengill, while the percentage of carbon 



I). K. D. Vi(Jeiisk. Selsk. Skr., 7. Hække, naturvidensk. og niatheni. Aid. VIII. -i. tJ3 



