T. S. Hunt on Lithology. 91 
prussian blue or green compound; for I find that the green 
reaction can be obtained in presence of a large excess ot free 
ammonia, together with which, it is hardly necessary to remark, 
the last mentioned compounds could not exist. I propose to 
return to the subject of the ruthenium reactions at a future 
occasion. 
Philadelphia, March, 1864, 
(To be continued.) 
Agr. X.—Contributions to Lithology; by T. Sterry Hunt, 
M.A,, F.R.S.; of the Geol. Survey of Canada. 
Parr II].—On Some Erverive Rooks, 
In this Journal for March, 1860, ( [2], xxix, 282) there is a 
short note, pointing out the existence, in the vicinity of Montreal, 
of several interesting classes of eruptive rocks, including quartz- 
iferous porphyries, trachytes, phonolite, dolerites, and diorites, 
tis proposed in the third part of the present paper to describe 
the results of some chemical and mineralogical examinations of 
these rocks, and to give, by way of preface, a description of their 
peeetaphical distribution and geological relations, They may 
Tass k 
hills of eruptive rock belonging to the Montreal group. Beside 
these, numerous smaller intrusive masses in the form of dikes 
