382 Analyses of Books. [May, 



present immense in comparison with the matters held in solu- 

 tion ; but these matters exist in it : they are deposited, as M. 

 Berthier has observed, at the waters of Vichy, St. Nectaire, Sec* 

 not only separately, but nearly in the same order, as the calca- 

 reous and magnesian formations. The first deposits, those 

 which are nearest the spring, this able chemist tells us, are also 

 those most charged with peroxide of iron and silex ; the lime- 

 stone, still ferruginous, then follows, and is the more pure and 

 more separated from these two substances, the more distant it 

 is from the point where the spring rises from earth; the carbon- 

 ate of magnesia is the last deposited. 



" Without wishing to establish any real resemblance between 

 this succession and that of our rocks ; without wishing to repre- 

 sent that these rocks, certain beds of which show too clearly 

 the characters of mechanical aggregation for them to have been 

 formed by solution, have been deposited by the mineral waters 

 of the ancient world, we cannot avoid remarking that commenc- 

 ing with the chalk, we find a series of rocks, the nature and 

 succession of which are nearly the same as those which M. 

 Berthier has observed in the deposits from mineral waters. 

 Thus, first, a new formation, i. e. a new emission of dissolved 

 matter would appear to commence above the chalk, at first de- 

 positing silex and iron, represented, one by the beds of sand 

 and sandstone, and the other by the iron ore found so abund- 

 antly in the deposits of lignites and plastic clays which cover the 

 chalk ; secondly, the more or less compact limestone, accompa- 

 nied by iron and silex in the lower beds, and by silex in the 

 upper beds; the magnesite also accompanied by silex, which 

 still occurs in the lower gypsum beds ; this silex is partly 

 soluble in alkaline liquids, like that of the calcareous deposits 

 of certain mineral waters ; fourthly, the gypsum, the most 

 soluble substance of all those we have named, and which should 

 be the last deposited. 



"We do not pretend to draw any other conclusion from 

 these different resemblances ; but it appeared to us right to 

 hazard them, if it were only to engage the attention of chemists 

 and geologists." 



From this extract the reader will be able to judge of the man- 

 ner in which Mr. de la Beche has executed his task : and we 

 will conclude by recommending this work to all students of 

 geology ; to whom it will be highly useful, by enabling thein to 

 compare our own rocks with the similar formations on the conti- 

 nent which are described in it. B. 



* Annates ile Chim. et de Physique, t. xix. p. 134. 



