388 J\liscellanies. 



or less lamellar. It forms almost the whole of secondary countries, 

 in which it presents a compact structure. In tertiary formations it is 

 also very abundant, yellowish, loose, and more or less solid. In tu- 

 fas, and concretions, which continue to be found on the surface of 

 the globe, it is not less predominant ; finally, it enters into the com- 

 position of a great number of organized bodies. 



The variety of forms presented by carbonate of lime is immense, 

 but they may all be arranged in two classes. The first, whose 

 primitive form is a rhomboid — belonging to substances properly call- 

 ed calcareous ; the second, whose primitive form is a right rhomboi- 

 dal prism, belonging to Arragonite. 



The circumstances which determine the crystallization are un- 

 known. All we know is that Arragonite is found in particular beds, 

 (volcanic or metalliferous regions,) which may influence its formation. 



When these two substances are crystallized, nothing is more easy than 

 to distinguish one from the other by cleavage, the measurement of the 

 angles, and by the hardness; but when they are not crystallized we must 

 have recourse to a particular process, which M. Becquerel points out, 

 and by which he proves that ^os-/e7-n, the concretions called T'ivoli 

 sugar-plums and tabular white marble, present the rhomboidal cleav- 

 age, whWeJistular stalactites, alabaster ofmontmartre, Sic. present that 

 of Arragonite. M. Becquerel describes an apparatus by which, with 

 electrical forces, he crystallizes Arragonite. He obtains the form of 

 a quadrangular prism with two dihedral summits ; it is that under 

 which nature presents it. The same apparatus serves to form the 

 double crystallized carbonate of lime and magnesia, (dolomite,) the 

 protoxide of copper, and the blue and green carbonates of copper. 

 Analysis proves that the crystals of Arragonite which he has obtain- 

 ed, have absolutely the same composition as those of calcareous spar, 

 and differ from it only in crystallization. — Rev. Ency.JuiUet, 1832. 



GEOLOGY. 



1. JVew cave of Bones. — An account of this cave was read by 

 Marcel de Serres to the French Academy on the 28th of May. It 

 exists in the environs of Mialet near Anduze, department du Gard. 



The principal cave has been long known, having served as a re- 

 treat for the Camisards, who had made a kind of fortress of it, in 

 cases of sudden attack. It had frequently been visited by the cu- 

 rious, but without any suspicion, until lately, of its containing fossil 

 bones. 



