83 261 



tliat, provided the water which rushes into the upper part of the spring channel 

 carries with it an appreciable amount of emanation, a parallel could be shown 

 between the quantity of emanation and the amount of water in the springs. An 

 exhaustive investigation of the amount of water and of the emanation would there- 

 fore doubtless give a decisive answer to this question. On our journey, we were 

 so much occupied with other investigations, that time did not permit of our meas- 

 uring the volume of the water, but our observations on the spot indicate that an 

 increase in the volume of water is generally attended by a corresponding increase 

 in the radio activity. Mud pools with little water, as for instance those at Hvera- 

 vellir and at Reykjafoss, often seemed to exhibit a surprisingly slight radio activity 

 in comparison with the other springs of the same group. 



Of course these experiments throw no light on the question as to what extent 

 the radio activity of the springs is due to emanation conveyed by atmospheric 

 water into the upper part of the channel. But there is no doubt that a great deal 

 of the emanation in the springs must come with the other exhalations from the 

 interior, where all the springs in the same group have a common channel, or 

 perhaps even all the way from the seat of the heat energy of the springs, for 

 otherwise it is difficult to understand why the amount of emanation in proportion 

 to the other gases is usually of the same magnitude in the same group. 



I have already shown, (page 63) that spring channels may often extend deep 

 down into the earth before joining the main channel of the group. Even two 

 springs situated side by side may have channels independent of each other deep 

 down in the earth. But it is evident that the longer the individual channels are, 

 and the deeper they extend down in the earth, the more probable it is that the 

 decay of the emanation and the supply of fresh emanation from the side channels 

 will cause the amounts of emanation from the two springs, originally equal, to be 

 finally quite different. When, therefore, we find that the three springs Namafjall 

 Nos. 1, 2 and 3 have practically an equal radio activity, it must undoubtedly be 

 attributed to the group in question having a common channel which divides into 

 three not far from the surface. 



The same is probably the case with the two hot springs in Vestur-Hveradalir, 

 i. e. Kerüngarfjöll Nos. 1 and 2. 



Inasmuch as the Icelandic hot springs are all radio active, and as radium 

 spontaneously produces heat, it seemed quite reasonable to conclude that the heat 

 energy of the springs is due to radium. I therefore expected that my measure- 

 ments of the radio activity of the hot springs would render valuable information 

 on this point. But this has not been the case. There are no definite proofs that 

 the heat energy of the springs is directly connected with their radio activity. The 

 fact that the nitrous springs at Reykir are both colder and less radio active than 

 similar springs at Laugaras and Grafarbakki, is probably due to other causes. And 

 on the other hand, although they are apparently quite as vigorous, the hot springs 

 at Hengill are less radio active than those at Hveravellir and Kerlingarfjöll. 



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