THE STUDY OF CHEMICAL GEOLOGY. 
249 
arrived at by the mere examination of their mineral character 
and position in the field ; mathematics and astronomy lent 
their aid in solving many important problems connected with 
the phenomena of our sphere ; and mineralogy was required to 
determine the mineral components of which its crust was 
formed ; whilst a knowledge of optics and the use of the micro- 
scope enables the geologist to extend his investigations far be- 
yond the limits to which his naked eye could otherwise convey 
him.* 
When, however, the geologist advances further, and desires to 
study something more than the mere external forms and physical 
characters of the materials of which our globe is built up, he is 
compelled to call in the aid of chemistry, for it is by chemical 
science alone that he can be enabled to demonstrate the true 
nature of these materials, to explain their, formation or origin, 
or to discover the causes which have produced the changes or 
alterations which they have already experienced, or which they 
may now be undergoing. 
The great importance of the application of chemistry to 
geology is now universally acknowledged ; yet, although on the 
Continent much has been done of late years in this direction, it 
is surprising how little attention has been directed to the study 
of chemical geology in Grreat Britain. 
British geologists seem to have all but exclusively devoted 
themselves to the consideration of the stratagraphical and palm- 
ontological succession of the sedimentary beds, and have, as a 
rule, studiously avoided the investigation of all geological phe- 
nomena which did not appear to admit of explanation by the 
agency of mere mechanical forces. At the same time, however, 
it is curious to observe that there have not been wanting those 
who have put forth vague theories to account for the nature and 
formation of our metaihorphic and eruptive rocks, &c., hypo- 
theses which, unfortunatel}^, can only be regarded as flights 
of imagination, since it is well known that, with but some few 
rare exceptions, no chemico-geological investigations or chemical 
analyses of British rocks or of their component minerals have as 
yet been made which could serve as a basis for any such gene- 
ralisations. 
Foremost as this country is in all the other departments of 
geology, Grreat Britain must, however, be admitted to be far 
behind in chemical geology ; so that, by directing attention to 
the subject, it is to be hoped that others may be incited to take 
up and devote themselves to this most interesting and prolific 
branch of scientific enquiry. 
* Vide “ The Microscope in Geolog}^,” Popular Science RevieWf vol. vi., 
Oct. 1867, p. 355, et seq. 
