oQ6 Reviews — E. Daiihree — Stibterranean Waters. 



quite sufficient for our present purpose that water should be deemed 

 an important agent in causing " stones to grow." But a few years 

 have elapsed since a celebrated geological chemist declared that the 

 alkahest, or universal menstruum, was neither more nor less than 

 water, aided by heat, pressure, and the presence of other substances. 

 The author of the work now under consideration has already de- 

 monstrated in his celebrated " Etudes synthetiques " the important 

 part played by underground waters charged with various substances 

 in the formation of minerals ; and he now proceeds to point out how 

 their history furnishes us with a remarkable example of the continuity 

 of operations past and present. Even in places where they no longer 

 flow, these underground waters have left us indications of their 

 movements and their chemical energy, so that we are enabled to 

 follow them in all the details of their "regime." 



Of all mineral substances which have been formed in the wet way, 

 zeolites are amongst the most obvious, and Mons. Daubree has else- 

 where observed that these may be regarded as a kind of extract of 

 the rocks, which have themselves been subjected to continued lixi- 

 viation. Entering more fully into this question in the present work, 

 he gives examples of their development and mode of formation, 

 together with that of the associated minerals, quartz, agate, and 

 chalcedony. There is no lack of appropriate illustrations : the 

 section of an agate is particularly fine. He still seems to regard the 

 canal shown by some of them as an inlet of infiltration. The zeolitic 

 minerals of Plombieres are discussed at some length : sections of 

 the zeolite-bearing bricks are given, effective alike for showing the 

 minerals themselves as well as the structure of the brick. The 

 bricks thus transformed present considerable resemblance to certain 

 altered volcanic rocks. The siliceous products of the bricks resemble, 

 he says, the acid rocks, whilst the zeolites and globules of palagonite 

 in these same bricks recall the basic rocks. All these changes have 

 been elFected since the days of the Eomans by waters of a moderate 

 temperature. 



The study of the formation of metalliferous deposits affords still 

 more remarkable testimony alike to the solvent and depositing 

 powers of underground waters. Substances, which under ordinary- 

 conditions are regarded as insoluble, have been deposited in various 

 ways, as in veins, segregations, beds, etc. A pi-opos of this subject 

 Mons, Daubree does not fail to point out the celebrated instance at 

 Bourbonne-les-bains, so well described in the " Etudes synthetiques," 

 where old Eoman coins by their decomposition have yielded metallic 

 sulphides under the action of warm mineral waters. 



This branch of the question is a very large one, and has received 

 ample treatment both from Mons, Daubree, and also from the late 

 John Arthur Phillips, in his excellent treatise on " Ore Deposits." 

 One cannot fail to perceive that these authors are disposed to ascribe 

 the bulk of the phenomena, as regards veins, segregation-veins, 

 beds, etc., mainly to the action of waters, warm or cold. It is true 

 that such actions are often the most powerful in the neighbourhood 

 of eruptive rocks, which are frequently accompanied by veins 



