xii, a, 6 Heise: Radioactivity of Waters, Northern Luzon 299 



of minor interest. A collecting can, full of the gas taken from 

 one of the excavations by downward displacement of water, 

 proved to be radioactive, as indicated in Table I. 



For completeness, I have compiled the available chemical data 

 on the waters studied and have included them in Table II. All 

 of the waters tested for radioactivity in 1917 were analyzed at 

 the source by Mr. A. S. Behrman, chemist of this Bureau, who ac- 

 companied me on the field trip. In the case of highly mineral- 

 ized waters, or when additional gravimetric determinations were 

 desired, samples were taken to Manila in glass-stoppered bottles 

 and analyzed in the laboratory. It should be noted that the data 

 given under "total hardness" were obtained by a modification 

 of the Blacher ' potassium palmitate method and represent com- 

 bined calcium and magnesium content. 



Of the numerous salt springs examined, none showed more 

 than small amounts of activity. The hot springs, too, were only 

 slightly or not at all radioactive. These results are in agreement 

 with those obtained elsewhere 8 and are to be expected from 

 the low solubility of radium emanation in hot water or con- 

 centrated salt solutions. A number of waters low in radio- 

 activity are also low in dissolved mineral matter. This is prob- 

 ably of little significance, except to show that certain sources, 

 instead of being deep-seated springs, were but little more than 

 seepage water, percolating the soil for comparatively short dis- 

 tances. It might be pointed out that the most radioactive waters 

 encountered were high in calcium and magnesium content, in- 

 dicating an origin in calcareous material. The work done in 

 the Philippines up to the present time is still insufficient to 

 justify conclusions, so that the cases noted should be regarded 

 as isolated observations, at least for the present. However, it 

 is worthy of note that this peculiarity is distinctly at variance 

 with the usual observation 9 that the water from igneous rocks 



' Blacher C, Griinberg, P., and Kissa, M., Die Verwendung von Ka- 

 lhunpalmitat bei der Wasseranalyse, Chem. Zeitg. (1913), 73, 56-8. This 

 method has been adapted to field work by Mr. A. S. Behrman and now 

 forms one of the regular routine determinations in the Bureau of Science 

 field assay of water. 



8 cf . von Hofer, H., Radioactive springs, Intern. Zeitschr. Wasser- 

 versorgung (1914), 1, 52-5, 90-3; through Chem. Abst. (1915), 9, 1714. 



9 cf. Clarke, F. W., Data of geochemistry, Bull. U. S. Geol. Surv. (1916), 

 616, 315. Sahlbom, N., Arkiv. Kemi. Min. Geol. (1915), 6, No. 3, 1-52; 

 through Chem. Abst. (1916), 10, 1134. 



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