68 Notices rejecting New Books. 



becomes more manifest when we inquire as to the analogy or 

 dissimilarity to existing forms, — its mode of occurrence — the rela- 

 tive abundance or scarcity — the broken or preserved condition — the 

 organisms with which it is associated — the nature of the rock, mud, 

 sand, gravel, or calcareous matter, — and other circumstances which 

 would lead to the inference respecting the probable depth of the sea, 

 and whether the creature had lived on the spot or been drifted from 

 a distance. So with a mineral, its chemical constitution is one 

 thing, but its mode of occurrence another — the species with which 

 it is associated — the composition of the rock in which it is imbedded, 

 whether intimately mixed, occasionally aggregated or in distinct 

 crystals — whether occurring in veins or fissures — the chemical rela- 

 tions of the substance to the containing rock, whether segregated 

 during consolidation of the rock or subsequently elaborated, are 

 some of the points of inquiry in the ' paragenesis ' of a mineral species. 



Independently of mineralogy, geology has also received important 

 aid from chemistry, in determining the composition of rocks and 

 the changes they have undergone, in suggesting the various pro- 

 cesses of fossil ization, in explaining the results of volcanic and 

 pseudo-volcanic phsenomena, &c. It is well known that Prof. 

 Bischof has devoted a considerable portion of his time to the 

 bearings of chemistry on mineralogy and geology, and his original 

 work evidences a vast amount of labour and research in collecting 

 together so much useful matter. The English edition is translated 

 from a revised copy by the author of the^Joriginal work ; the facts 

 are more condensed, the subjects are arranged in a more systematic 

 order than in the German edition, and treated in such a manner, as 

 to render it not only a useful work of reference, but a standard 

 treatise for some time upon many of the important and interesting 

 questions in chemical and physical geology. The present edition 

 is by no means a mere translation or abridgement of the German, 

 but an independent work, in which the additional chemico-geological 

 facts ascertained since the publication of the latter, have been incor- 

 porated and concisely illustrated. 



Our space will scarcely permit any details of the numerous 

 valuable facts contained in the work, but the following are some of 

 the principal subjects treated in the first and second volumes. The 

 laws of combination in the mineral kingdom as regards the decom- 

 position, conversion and formation of minerals and rocks ; and 

 pseudomorphism, which affords such important aid, and is in a great 

 measure the storehouse out of which the knowledge of these laws 

 are chiefly to be drawn, is fully considered, as described from the 

 labours of Rose, Haidinger, Blum, Breithaupt, and the author. 



The waters on tlie earth, by which the greatest part of its surface 

 has been formed or modified, the deposition of chemical and mecha- 

 nical sediments and those from organic agency, the share which the 

 mineral kingdom takes in thechange of the constituents of atmospheric 

 air, are successively treated ; the later chapters of the first volume are 

 devoted to the consideration of the simple salts, according to their 

 distribution and importance. 'J'he second volume is more useful to 



