310 The Philippine Journal of Science \m 



Table I. — Variation in radium emanation content. 



Sibul Springs 



Do : 



Do 



Do 



Do... 



Do 



Flowing well, Parafiaque, Rizal 

 Do ._ 



Date of ex- 

 amination. 



Radium 

 emanation 



content 

 (as g. RaX 



10-12.) 



April 10, 1916 

 July 9, 1916 

 April 22, 1917 



do 



June 9.1917 

 July 1.1917 

 July 15.1917 

 June 19, 1916 

 June 2,1916 



1284 

 1293 

 1300 

 1280 

 1330 

 1270 

 1280 

 632 

 640 



The. differences between determinations of the radioactivity 

 of the same source at various times are well within the limits 

 of experimental error in this class of work. Though the work 

 on Sibul Springs was done in only a few months in the year, 

 determinations were made under greatly varied conditions. Si- 

 bul Springs has a very large flow throughout the year, but the 

 quantity of water changes appreciably with the season. The 

 readings in April, 1916, and April, 1917, were made after pro- 

 longed seasons of dry weather, at times of minimum water flow. 

 Though there was no sharply defined rainy season in 1916, the 

 July reading was taken during a period of frequent, though 

 not very heavy, rains, at a time of increased flow. There was 

 much heavier rainfall in 1917 than during the corresponding 

 period in 1916, so that the July, 1917, readings were taken 

 during a time of heavy precipitation and great flow. It is, 

 therefore, reasonable to suppose that the readings noted are 

 representative of the radioactivity of Sibul Springs through- 

 out the year. 



The determinations of the activity of the Parafiaque flowing 

 well are too few in number to be conclusive; they are so con- 

 cordant, however, that they may be regarded as corroboratory 

 evidence. 



The data at hand clearly indicate, therefore, that the radio- 

 activity of a deep-seated ground water may remain remarkably 

 constant for long periods. 



As the waters at Sibul Springs have been highly regarded for 

 a long time because of their supposed medicinal virtues, they 

 have been frequently analyzed. It is of interest to point out 

 that surprisingly little, if any, change has been noted in the 

 chemical character of the water for a long period of time. In 



