xii. a. 6 Heise: Radioactivity of Waters, Northern Luzon 305 



The general statements in the literature regarding radioac- 

 tivity indicate that — 



The phenomenon is perhaps most common among waters of volcanic 

 .origin, or at least among thermal springs. 12 



The present study seems to show that this generalization does 

 not hold for Philippine waters, though the work is still too 

 preliminary in character to justify positive statements. 



u Clarke, F. W., loc. cit., 215. 



