MUSEUM OF COMPARATIVE ZOOLOGY. Zot 
A rough analysis yielded results as below. This indicates that the 
rock is more nearly related to the andesites than trachytes, though 
abnormally rich in potash. The rock was found to contain a notable 
amount of free sodium chloride, derived presumably from ocean spray, 
which may in part account for the high percentage of soda. 
Per Cent. 
SiO, 56.50 
Al,03, Fe,03 28.20 
CaO 2.83 
MgO -98 
K,O 4.25 
Na,O by difference 6.68 
. 99.44 
WasuHinaton, D.C., October, 1892. 
