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XLVII. Notices respecting Neiv Boohs. 

 On the Alteration of Superficial Deposits by the Infiltration of 

 Atmospheric Waters, Sfc. [Memoire sur les Phenomenes d' Altera- 

 tion des Depots superficiels par V Infiltration des Eauoc meteoriques, 

 etudies, 6fc.~\ By Ernest Van den Broeck, Conservator in the 

 Boyal Museum of Natural History at Brussels, &c. 4to. 180 

 pages, with coloured lithographic plate and numerous woodcuts. 

 Brussels: E. Hayez, 1881. 



THE author has herein brought together on a systematic plan the 

 observations made by himself and others on the results of the che- 

 mical action of rain-water on superficial deposits and on rocks lying 

 within its influence. This subject has, of course, been within the 

 cognizance and under the study of geologists from an early period ; 

 and many notes and papers have been given on the several facts 

 observed ; but M. Yan den Broeck has taken this subject particu- 

 larly under consideration, and furnishes this compendious and useful 

 memoir, based on careful notes on the phenomena of superficial 

 alteration observed in Belgium and elsewhere, and illustrated with 

 many clear sections, some of which are coloured. 



In treating of the various aspects of superficially- altered rocks, 

 and of the results of meteoric (atmospheric) agency, the author 

 first notices the mechanical disintegration, and then the chemical 

 dissolutions, decompositions, and new combinations ; also the uni- 

 versality of these phenomena. Then he takes : — (1) the felspathic 

 rocks and their veinstones ; (2) the metalliferous deposits, especially 

 where sulphur and iron play an important part ; (3) the argillaceous 

 schists and the clays, the latter being pure, sandy, or glauconitic ; 

 (4) the siliceous rocks, with interesting remarks on changes in both 

 shallow and deep deposits, alterations and accumulations of quartz, 

 modifications of jasper, colloid silica, decomposition of glauconitic 

 sands, " silex nectique," and the Tertiary Millstone of Paris ; (5) 

 calcareous rocks, especially limestone-gravel, Cretaceous strata, the 

 " clay with flints," sand-pipes, &c. The Appendix treats particu- 

 larly of infiltrations in the Quaternary beds, such as the Hesbayan 

 loam or loess, and the Diluvium of the valley of the Seine. 



The chemical phenomena of dissolution and oxidation, which are 

 the essential points in M. Van den Broeck's researches, as here de- 

 tailed, have certainly been long known and recognized ; but we 

 have to thank him for collating and coordinating both the facts 

 (some of which are quite new) and his inferences, as shown in this 

 memoir and thus made available for further consideration, in view 

 of the importance which these hydrochemical operations have in 

 falsifying certain aspects of geological sections in all parts of the world. 



The Ground (Substrata) of the Cities of Europe. Geological Studies. 

 By Felix Karrer. [per Boden der Haupstddte Europa's 6rc.~\ With 

 23 woodcut sections. 8vo. 68 pp. Alfred Holder : Vienna, 1881. 

 This is a compendious and highly instructive memoir on the geolo- 

 gical structure of the areas on which the seven great cities of Europe 

 are situate. The Vienna Basin, traversed by the valley of the 

 Danube, comes first, and is rather more fully described, as to both 

 present and past conditions, than the others (pp. 1-16) ; Paris and 



