10 Sir R. I. Murchison’s Address on the 
lic by the last-mentioned of these geologists,* who, being him- 
self an accomplished chemist, has given us some good illustra- 
tions of the probable modus operandi in the bringing about of 
these changes. 
e importance of the inquiries to be made by chemical geol- 
ogists into this branch of our science was not lost upon the ear- 
lier members of the British Association. Even in the year 1833, 
a committee was appointed to endeavor to illustrate the phenom- 
ena of the metamorphism of rocks by experiments carried on in 
iron-furnaces. After a series of trials on various mineral sub- 
stances, the Rev. W. Vernon Harcourt, to whom we owed so 
seeing that my eminent friend has, in the spirit of true induc- 
pyar which resolve some of the difficulties of the problem. 
e has brought before us, in a compendious digest, the history 
of the progress which has been made in this branch of our sci- 
ence, by the writings of La Place, Fourier, Von Buch, Fournet, 
and others; as well as by the experimental researches of Mits- 
cherlich, Berthier, Senarmont, Daubree, Deville, Delesse and 
Durocher. Illustrating his views by reference to chemical chan- 
Bes in the rocks and minerals of our own country, and fortifying 
is induction by an appeal to his experiments, he arrives at the 
conclusion, that there existed in former periods a much greater 
intensity of causation than that which now prevails. His theo 
is, that whereas now, in the formation of beds, the aqueous ac- 
tion predominates, and the igneous is only represented by a few 
solfataras, in the most ancient times the action was much more 
* This Journal, May, 1861. 
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