1909-10.] The Chemistry of Submarine Glauconite. 373 
grains, in which the glauconite proper would appear to be enclosed by a 
network of foreign substance ; and the vehemence with which the grains 
fly into powder under the action of acid and alkaline solutions points in 
the same direction. On the whole, then, though it would be premature to 
regard the matter as settled, the probability is that glauconite is essentially 
a colloidal silicate. 
{Issued separately April 8, 1910.) 
