•3IS sciExNTiric News. 



peridot. The same nodules and the sarae crystals are 

 found in the sconce tliat compose the craters, whence these 

 lavas issued. The modern currents having; almost all flowed 

 ■ through narrow and deep valleys, the torrents have resumed 

 their beds, by hollowing out vast furrows in the lava. Hence 

 result sections admirable for their height, which sometimes 

 rear hes to 200 French feet ; for the regularity and dimen- 

 sions of the basaltic columns; or for their extent, as they 

 frequently reach whole leagues. These superb curtains are 

 ornamented with scoriae at top and bottom. The decompo- 

 sition of the lower scoriae gives rise in certain places to a cu- 

 rious phenomenon. The tuf, or wacke, resulting from it, 

 XrarsUjon. mixes with the river-mud or s-and, which the lava had cover*!' 

 £d, and these places exhibit a transition of the sort that 

 Werner admits: that of sand, or clay, to basa'.tes ! The 

 modern basaltic colufnns of Mezin are unquestionably the 

 finest ever yet observed, 

 Kewkfndof The whole system of Mezin rests on a new kind of gra- 

 granite. ^^jj^^ jj^^p ^i^ich pinit enters in the proportion of a twentieth, 



8 tenth, and even a third. This rock occupies a space of 

 more than 250 square leagues, and extends to what was for- 

 merly Foret, where it serves as a matrix to the su bstance that 

 was taken for emerald, but is only a translucid pinit. Of 

 this I satisfied myself pa the spot. 



SCIENTIFIC NEWS. 



Hfiport of the Proceedings of the Mathematical and Physical 

 Class of the French Institute* 



Respirati 

 fshes. 



ion of O) 



f Concluded from p» 240.J 



INCE Mr. von Humboldt*s return tb France, he has 

 made many experiments on the respiration of fishes, in con- 

 cert with Mr. Proven9al. Spallanzani and Sylvestre had 

 shown, that fishes do not breathe by decomposing water, as 

 some had supposed, but by water obstructing the oxigen 

 dissolved in it, or by coming to the surface to collect oxi- 



