Geology. 133 
II. GEOLOGY, 
1, On Some Points in Chemical Geology ; by T. Srerry Hunt, F.R.S. 
(Read before the Geol. Society of London, January 5th, 1859-—published 
860.).—In this paper the author discusses a number of 
questions which lie at the foundation of a true history of the chemistry 
the earth’s crust, and gives farther developments to some of his pecu- 
liar views, which were for the most part, first enunciated in this Journal. 
In regard to the metamorphism of sedimentary deposits, ¢. e., the conver- 
_ Sion of sands, clays and marls into crystalline stratified rocks, the author, 
after distinguishing between local and normal metamorphism, insists upon 
the frequent interstratification of unchanged fossiliferous limestones among 
crystalline schists as evidence that heat has not been the only agent in 
the metamorphism, which has moreover been effected at temperatures 
not very elevated, and by the intervention of alkaline solutions, in the 
absence of which, sediments may be heated to the same degree without 
change, 
Li The first announcement of this view will be found in this Journal for 
2 May, 1857 (vol. xxiii, p. 407), where the author, after describing some 
experiments with the Lier silicates, expresses the opinion that “ we 
have here the explanation of rock metamorphism in general.” Farther 
inquiries into the action of the soluble alkaline silicates will be found in 
this Journal for March and May, 1858 (vol. xxv, pp. 287-437), where 
the subsequent experiments of Daubrée are cited in confirmation and ex- 
tension of Mr. Hunt’s theory of the normal metamorphism of sediments 
ases are present only in smaller quantity, of kyanite, andalusite and 
xyd 
wal, pyro n 
author has however alluded to the probable direct formation of certain 
Tn the second place the author discusses the relations of plutonic to 
metamorphic sedimentary rocks, and concludes that the latter, becoming 
splaced by dis- 
Plastic Under the influence of water and heat, may be disp 
Tn the third place the author discusses the theories of Phillips, Bunsen 
and Durocher, as to the origin of intrusive rocks, and rejecting the notion 
that these are derived from the supposed fluid interior of the earth, re- 
