' Boltwood — Radio-activity of Natural Waters. 385 



Samples JSTos. 1 and 2 were tested for radium salts in solu- 

 tion with negative results. It has been shown by Bumstead 

 and Wheeler that no radium salts are present in the !S T ew 

 Haven water (No. 3). 



The radio-active properties of the gases from the first two 

 samples were carefully examined and were found to corre- 

 spond with those of the radium emanation. The activity fell 

 to one-half in approximately four days and the rate of decay 

 of the excited activity agreed with that of the " emanation X " 

 from radium. 



Origin of the Radio-active Properties. 



The following experiments were carried out with a view to 

 determining the possible source of the radio-active properties 

 in the waters. 



A quantity of uranium minerals was pulverized in an iron 

 mortar and passed through a 100-mesh sieve. The minerals 

 consisted chiefly of uranophane, but contained also some gum- 

 mite, autunite and a small quantity of uraninite. The greater 

 quantity of the material represented the final decomposition- 

 product of uraninite when subjected to the action of percola- 

 ting waters. The material taken weighed 80 grams. It was 

 placed in a flask and about 500 cc of distilled water were 

 poured over it. The contents of the flask were mixed 

 thoroughly and allowed to stand, with occasional shaking, for 

 about twenty-four hours. Some of the mineral was in such a 

 fine state of division that the water remained very turbid after 

 standing undisturbed over night. 



The mineral was filtered off on a Buchner filter and the 

 filtrate was boiled (to expel emanation). The water was 

 cooled, introduced into a two-liter bottle with glass stopper, 

 diluted with distilled water until the bottle was quite full and 

 the stopper tightly inserted. The water was allowed to stand 

 for four days, and the gases which it contained were then 

 boiled off and tested in the electroscope. The activity of the 

 gas was equivalent to O016 division per minute. 



After filtering off the water as described above, the pow- 

 dered minerals were washed twice with distilled water and the 

 excess of water removed by suction. 100 cc of cold distilled 

 water were then poured over the mass on the filter and drawn 

 through it, this filtrate being separately collected. The filtrate 

 was allowed to stand in an open beaker for one-half hour and 

 was then boiled, the gases given off being collected and intro- 

 duced into the electroscope. The 'leak at the end of three 

 hours was 0*240 division per minute. 



The mineral powder on the filter was washed back into the 



Am. Jour. Sci. — Fourth Series, Yol. XYIII, No. 101.— November, 1904. 

 26 



