EFFECT OF TROPICAL SUNLIGHT ON THE ATMOSPHERE. 277 



Volts. 



per hour 



151.51 • 

 146.5 



5.0 



The water is radioactive. 



9. Finely ground Manila copal resin. Such resin is continually being oxidized 

 rather rapidly by the air and gives a strong test for hydrogen peroxide. 



Time, 

 (a. in.) 



9.45 



10.45 



No activity. 



10. Philippine clay. 



Time, 

 (a. m.) 



11.37 



(p. m.) 



1.27 



Slight activity. 



11. Philippine clay. 



Time, 

 (p. m.) 



2.08 

 3.08 

 Very slight activity. 



12. Philippine clay. 



Volts. 

 167.1 



152.6 



Volts 

 per hour. 



7.5 





Volts 



^olts. 



per hour 



200.81 





194.1 



6.7 



Time, 

 (a. m.) 



9.05 

 10.05 



Volts. 

 173.3) 

 167.11 



Volts 

 per hour. 



6.2 



Very slight activity. 



13. Barium sulphate precipitate formed in some rain water collected on 

 February 11. 



Volts. 

 182.0 

 175.5 



Volts. 



173.9 



138.3 



Volts 

 per hour. 



Time, 

 (a. m.) 



11.55 



12.55 



Slightly active. 



14. Powdered gold ore from Benguet. 



Time, 

 (p. m.) 



1.05 

 4.05 

 Slightly active. 



15. Black sand from Nueva Eeija. This black sand contains magnetite, zircon, 

 gold, platinum, and probably iridium and monazite. The decided activity was 

 ascribed to the monazite. 



6.5 



Volts 

 per hour. 



11.9 



Time. 

 (p. m.) 



2.05 

 3.35 



Volts. 



173.9 

 117.4 



16. Benguet gold ore measured in large pieces. 



Time, 

 (a. m.) 



11.15 

 1.00 



Volts. 

 134.1 

 118.2 



Volts 

 per hour. 



37 



Volts 

 per hour. 



