ee dhed, e 
es ee aes 
437 
reason we beg to reserve the field for a short time. We expect in our 
next communication to be able to report more authoritatively on the 
radio-activity of the Taal waters, including those of the lake inside the 
present active cone, and an expedition will probably be organized to 
obtain samples before the eruptions attendant upon the rainy season 
may possibly have destroyed the lake. We believe such observations will 
be of value in judging certain theories of the present day concerning the 
radio-activity of the surface of the earth. For the sake of completeness 
an analysis of the water of the larger lake surrounding the volcano, which 
was made some two years ago by Mr. F. A. Thanisch, formerly of this 
Bureau, is appended. 
{Results expressed as parts in 100 ec.] 
Total residue 0.1716 
Fixed residue 0. 1484 
Loss on ignition 0. 0232 
Free NH, Trace. 
Nitrites Traces. 
Fe,O, 
Al,O, \ 0. 00042 
Ca ; 0. 005339 
Mg 0. 004942 
Na 0. 045634 
SiO, 0. 00315 
A Cl 0. 0720 
SO, ~ 0.01913 
CO,, as bicarbonate, Considerable. 
The water has a slightly alkaline reaction and contains a slight white 
deposit. 
The above demonstrates the radical difference between the waters of 
‘the lakes within the crater and of that of the lake surrounding Taal 
Mountain. 
