366 



THE GEOLOGIST. 



sequence, at the level of tlie sea itself a liigher boiling point of 

 water, coii23led witli a generally higher temperature of terrestrial 

 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 quantitatively 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 ingi^edients to a higher level than 

 at present. Gr. BischofF 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 certain 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 

 Leonhard and Bronn's " Jahrbuch," 1844, p. 257, although I cannot 

 share the opinions founded thereupon as to the infiltrative formation 

 of all ore-veins. I must admit, however, that Bischofi" has proved 

 the possibility of the infiltrative fiUing-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 

 fissm^e-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 fissui^es, according to 

 their temperatm^e ; and also, in like manner, the variable conduct- 

 ibility, chemical afl&nity, and dissimilarity of the neighbouring rock 



