BORAX LAKE. . 265 



named and that there is here a repetition on a small scale of the phenomena 

 of the larger Snlphnr Bank. 



Borax Lake is a small and sliall(.)\v sheet of water of variable area. 

 Professor Whitney was informed that in 18G1 it dried np entirely. The 

 examinations of the region described in the last chapter make it clear that 

 the nearly flat area in which this pond is situated was formerly covered b}- 

 the waters of Clear Lake. Although Borax Lake receives the drainage of tlic 

 surrounding hills, it is still but little elevated above the larger body of water 

 From this it is separated by a low ridge mainly and perhaps wholly com- 

 posed of the obsidian and pumice described upon a preceding page. 



The bnracic character of the lake was first detected by Dr. J. A. Veatch' 

 in 185G. Later large quantities of borax crystals were extracted from the 

 mud and borings were made in the bottom with a view to renewing the sup- 

 ply, but in vain. Professor Whitney very properly regarded this lake as 

 an evidence of former volcanic activity; but, to make sure that the borax 

 was not leached out of the surrounding declivities by rain and merely con- 

 centrated here, I had careful tests made of large quantities of the meta- 

 morphic rock and obsidian. They showed no borax. 



The water of Borgx Lake was analyzed by Dr. Melville, and the 

 composition of one liter was found to be as follows: 



Grams. 



Silica, SiO^ "01"^ 



Alumina, Al-O^ 0. 00;>y 



Ferrous carbonate, FeCO' 0. 00.)G 



Mangauous carbonate, MuCO'J U. OOlrf 



Calcic carbonate, CaCO' 0. 0:i:!3 



Magnesium carbonate, MgCO' 0.9448 



Sodic carbonate, Na-CC 24. 1(i71 



Calcic pUospliate, Ca»P-0» 0.0225 



Calcic sulphate, CaSO^ 0.0204. 



Sodic sulphate, Na-SO-" "• ^'■^^'^ 



Borax, Na-B^O' 5.0040 



Sodic chloride, NaCl 38.9900 



Potassic chloride, KCl 2.2003 



Pota.ssic bromate, KBr 0.0447 



Organic matter 3.0184 



Carbon dioxide, C0= 0.6839 



Total 80.8654 



I Geol. Survey California, Geology, vol. 1, p. 98. 



