1918' 



THE 



AMERICAN JOURNAL OF SCIENCE 



[FOURTH SERIES.] 



Art. XXX. — The Radioactive Properties of the Mineral 

 Springs of Colorado; by 0. C. Lester. 



An investigation of the radioactivity of the nnmerons 

 mineral springs fonnd chiefly in the mountainous region 

 of Colorado was begun in the summer of 1914. The work 

 was under the auspices of the Colorado State Geological 

 Survey, which had undertaken some time previously a 

 study of these springs in relation to the geology of their 

 surroundings and the chemical constituents of their 

 waters. This previous study had provided a list of some 

 200 springs, giving locations, chemical analyses, and 

 considerable information of a general nature. Most of 

 these springs are highly mineralized, many of them are 

 very hot, and many give off large quantities of gas. The 

 present study was confined chiefly to the springs on this 

 list although not all of them are included. On the other 

 hand some springs not on the list have been included 

 when they appeared to promise results of interest. It 

 was impossible for several reasons to examine all the 

 known springs and there are doubtless many unknown to 

 us that might well be worthy of investigation. A few 

 springs are located in regions where travel was practic- 

 ally impossible except on foot or on horseback. Others, 

 owing to an unusually rainy summer for Colorado, were 

 rendered temporarily inaccessible by damage to roads 

 and bridges or were covered with water or the debris of 

 washouts. 



Since most of the springs are situated at distances 

 varying from a mile to more than fifty miles from the 



Am. Jour. Sci.— Fourth Series, Vol. XLVI, No. 275.— November, 1918. 



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