366 
THR GEOLOGIST. 
sequence, at the level of the sea itself a higher boiling point of 
water, coupled with a generally higher temperature of ten^estrial 
bodies, it must follow that the dissolving power of water was ex- 
tremely heightened, as indeed is even now the case in deep fissures 
and under high pressure, as for example in the geysers of Iceland. 
Under such circumstances it would be possible that the water dis- 
solved not only quantitativehj but also qualitatively far more consti- 
tuents than is at present the case, and especially than we can 
dissolve in our laboratories. In consequence of the general higher 
temperature of the earth, it was at the same time possible that the 
water could raise these dissolved ingredients to a higher level than 
at present. G. BischoiF has shown that the constituents of those 
class of ore-veins which in their composition resemble those at Frei- 
berg are soluble in water under cei'tain circumstances and in certain 
combinations. With reference to this, I think we can place the 
most implicit confidence in the excellent memoir on the subject in 
Leonliard and Bronn's " Jahrbuch," 1844, p. 257, although I cannot 
share the opinions founded thereixpon as to the infiltrative formation 
of all ore-veins. I must admit, however, that BischofF has proved 
the possibility of the infiltrative filling-up of such ore-veins as those 
of Freiberg. It is required, therefore, on this subject only to show 
that the hypothesis is in harmony with the independent facts and 
with the foregoing remarks. The first can only be done step by 
step in this volume, the last I shall proceed at once to investigate. 
A necessary consequence of the inequality of the temperature in 
the deeper and higher regions or zones of the water-filled fissures or 
fissure-systems must have been a constant circulation of water. 
That which at a great depth it dissolved out of the heated eruptive 
rocks (which are, according to our supposition, the primitive seat 
of metallic elements) it again deposited at a certain level above it, at 
a definite temperature. The deposition went on, according to cir- 
cumstances, either more or less energetically, or slowly and period- 
ically, and the deposit was in consequence either massive or 
stratified. The amount of this deposition must, at any one time, 
have been unequal at the various levels of the fissures, according to 
their temperature ; and also, in like manner, the variable conduct- 
ibility, chemical affinity, and dissimilarity of the neighbouring rock 
