164 
TRANSLATION. 
epochs of the globe, an increase which becomes more and more decided 
down to our own epoch, and which is not in harmony with the changes 
in the proportions of the other elements, appears to me to be due to a 
special cause: it appears to be difficult to give an account of it, without 
admitting the intervention of sea-water in the formation of igneous pro¬ 
ducts, at least during the later geological periods. Thus, like M. Abisch, 
I am led by my researches on rocks to consequences having points in 
common with the explanation which H. Davy had deduced from his 
studies on volcanic phenomena; but it does not appear to me to be ne¬ 
cessary to suppose unoxidized alkaline and earthy metals to exist in the 
incandescent zone which covers the earth’s surface. 
Three orders of facts require the intervention of sea-water in volcanic 
phenomena. 
The intervention of sea-water in volcanic effects appears to me to be 
based upon three great orders of facts :— 
1°. The action of elastic fluids, much more marked at present than 
formerly, on the phenomena and rocks of eruption. 
2°. The nature of these elastic fluids, among which are found in 
abundance aqueous vapour, hydrochloric acid, and the chlorides and 
acids of sulphur. 
3°. The considerable increase of soda in the more modern of the 
igneous rocks, whether they be derived from the acid or the basic layer; 
I should add, that this substitution of soda for potash is accompanied by 
the replacement of fluorine by chlorine. 
I might also add that many volcanic products contain, not merely 
organic matters, but, according to the observations of M. Ehrenberg, 
recognisable traces of organized beings, which prove clearly the addition 
of external elements in the formation of those products, whilst there is 
nothing similar in the ancient granitic rocks, which constitute purely 
endogenous masses. I am aware that there are certain difficulties inhe¬ 
rent in the hypothesis of an intervention of sea-water in volcanic action, 
but these difficulties are not insurmountable ; and we must, of necessity, 
take account of the whole of the facts I have noticed, as tending to the 
same conclusion. 
Circulatory Movement of Soda. —We know, moreover, that the sodi- 
ferous silicates are more easily decomposed than thepotassiferous silicates: 
thus in mineral waters, as in the sea-water, soda is the dominant alkali. 
It seems thus destined to a continual circulatory movement: removed 
from the rocks in decomposition by the infiltrated water, then, trans¬ 
ported to the sea by running water, it is brought back by deep crevasses 
to the subterranean foci, from which it issues again, partly as vapour, 
and partly incorporated in the lavas. 
(.To be continued.) 
