California, Oregon and Washington Territory. 233 
trated in the glass, as is the case with the hypersthene-andesite 
pumice. In this case the potassa in the residual glass is 1D ex- 
cess of the soda, while in the crystallized feldspar it bears to 
soda the proportion of about 1:7. To confirm if possible the 
results obtained by microscopic and chemical investigation 
Upon the feldspars in the dacite, we picked out a number o 
crystals to test by Dr. Szabé’s admirable and delicate method 
of determining feldspars in rocks by means of the color im- 
parted under certain conditions to the flame of a Bunsen 
burner. For the application of this method we are greatly 
hypersthene-andesites. And right here it may be well to point 
ut the relationship existing between hypersthene and olivine. 
A microscopic study of these intermediate rocks in conjunc- 
