448 A POPULAR EXPOSITION OF THE 
or animal remains. Fucoids or sea-weeds, it must be remembered, 
are the only vegetable matters hitherto discovered amongst the fossil- 
ized bodies of our Silurian and Lower Devonian rocks. But if we 
adopt this view, we must adopt, also, certain other and apparently 
unwarrantable conclusions. The organic remains of these strata are 
not more numerous than those of other strata in which not the slightest 
traces even of petroleum have been found; neither do they present 
any characters peculiar to themselves and suggestive of oil-forming 
capabilities. Hence we have to infer the existence in the Devonian 
seas in which these deposits were laid down, of a vast abundance of 
soft-bodied animals, or sea-weeds, of a nature-altogether unknown: a 
most gratuitous supposition. The enormous quantity of petroleum 
yielded by these sources, and by others in the American States and 
elsewhere, renders the formation of this substance from sea weeds or 
perishable animal remains in the highest degree improbable. 
But are we absolutely driven to the adoption of either of the above 
views, in order to explain the occurrence of petroleum in our Devo- 
nian strata? The question mainly turns upon this: Are we forced to 
assume with certain chemico-geologists—who refuse all explanations 
of natural phenomena incapable of being rendered evident by labora 
tory experiments—that all forms of carbon, and all compounds into 
which carbon enters (with the sole exception of carbonic acid, and 
that only in part) are necessarily of organic derivation? With all 
respect for laboratory investigations, some of which have shed much 
light on obscure geological problems, it cannot be doubted that this 
view assumes too much. There are many facts, universally recognized 
as such, which chemistry is quite unable to explain. The allotropic 
conditions of certain simple bodies, for instance, carbon amongst the 
number; the existence of chlorine, oxygen, &c., in the solid state in 
the greater number of their compounds; the peculiar condition of 
water in hydrated substances, and so forth. We have the positive 
fact likewise that carbon exists, as such, in meteoric stones; that it 
separates often in crystalline scales from molten iron; and that it is 
present in steel, a fusion-product, also, as sometimes prepared. Why, 
then, are we debarred from assuming its existence amongst the primary 
or original components of the earth-mass? During volcanic outbreaks 
in many parts of the world, petroleum has frequently made its appear- 
ance, through fissures on the sea-bed, or around the volcanic vent, ag 
one of the products of the eruption. This was memorably the case 
