| Geology. - pe 445° 
we es . : 
e genus Huronia he refers to Orthoceras (or Ormoceras if that genus 
be retained ), 
. Next follows the Report of T. Sterry Hunt, Chemist and Mineralogist 
to the Geological Survey. We have already quoted a few facts on min- 
erals from this report; also at page 217 an article on Ophiolites, and page 
361 a chapter on the Salines of Europe. e propose to cite farther on 
the subject of rocks at another time. There are also valuable chapters 
on the Metallurgy of Iron, Magnesian Mortars, the Purification of Plum- 
bago, and Peat and its products, which we must pass by. 
On the subject of metamorphism, Mr. Hunt adopts the view that the 
changes were produced by the action of chemical solutions, without the 
agency of a very elevated temperature. But he writes (p.477) as if this 
general idea were original with him, when it is the burden of Bischof’s 
great work, who makes all rocks by water and chemistry; and moreover 
It seems to be now the prevalent opinion on the subject. Bischof’s theory 
respecting the agency of chemical solutions—alkaline silicates and car 
bonates, etc.—is briefly considered in the writer's Mineralogy, 4th edition, 
(1854), p- 227, and its application to metamorphism is especially recog- 
nized on page 226, The writer suggested this general view of meta- 
morphism in this Journal in 1844, volume xlv, p. 104, and again in 1845, 
vol. xlvii, 135, and xlviii, 83, 92, and 397: at page 83, the agency of 
alkaline silicates is reeognized in pseudomorphism (though the method of 
ir action is not specifically explained); and, on page 92 of the same 
per, metamorphism is spoken of as pseudomorphism on a broad scale. 
orchhammer in 1844, in the Proceedings of the British Association, 
BS eS Tee ee ne ae eee 
EF: oe 
The quarto volume of twenty maps of the various lakes and rivers be- 
hed e Huron and the Ottawa, by Mr. Murray, show that the Cana- 
dian government is carrying forward the survey on the right plan—a 
