ee 
sat 
On Euphotide and Saussurite. 437 
From my own and others analyses of the alkaline mineral waters, d 
rived from argillaceous rocks, it will be seen that the salts of potash in 
these waters are generally in very small quantity when compared with 
the salts of soda, although potash predominates in argillaceous shales and 
clay-slates. The soda is therefore gradually removed from these rocks, by 
infiltrating waters, while the potash remains behind, and hence it hap- 
~pens that when these rocks, from which the lime, magnesia and oxyd of 
iron have been dissolved, are subjected to the process of metamorphism, 
potash-feldspar will predominate, together with quartz from the deficiency 
of bases, while silicates like cyanite and staurotide may be formed from 
the excess of alumina, The more quartzose sediments, other things be- 
Montreal, March 10, 1858. 
» On Euphotide and Saussurite ; by T. Srerry Hunt. (In a letter 
to J. D. Dana, dated Montreal, March 16, 1858.)—Through the kind- 
ness of Prof. Arnold Guyot I have had an opportunity of examining a 
of 83—3-4. My own analysis of a fragment from Mt. Rose, with a den- 
sity of 3-36, gives the composition of a lime-alumina epidote, with a 
little soda, The analyses of Boulanger of the saussurites of Mt. Genévre 
Composition the variety from near Genoa, analyzed by Schafhaiitl. 
lithologists, 1 pro soon to send*you my results, in a detailed form, 
With a sketch op On Habis of euphotide, 
