ISO COSMOS. 



mixture of oryctogmstically distinct crystalline components! 

 These differences have led mineralogists to separate these cos- 

 rnical masses into two classes, namely, those containing nick 

 elliferous meteoric iron, and those consisting of fine or coarse- 

 ly-granular meteoric dust. The crust or rind of aerolites is 

 peculiarly characteristic of these bodies, being only a few 

 tenths of a line in thickness, often glossy and pitch-like, and 

 occasionally veined.* There is only one instance on record, 

 as far as I am aware (the aerolite of Chantonnay, in La Ven- 

 dee), in which the rind was absent, and this meteor, like that 

 of Juvenas, presented likewise the peculiarity of having pores 

 and vesicular cavities. In all other cases the black crust is 

 divided from the inner light-gray mass by as sharply-defined 

 a line of separation as is the black leadon-colored investment 

 of the white granite blockst which I brought from the cata- 

 racts of the Orinoco, and which are also associated with 

 many other cataracts, as, for instance, those of the Nile arid 

 of the Congo River. The greatest heat employed in our 

 porcelain ovens would be insufficient to produce any thing 

 similar to the crust of meteoric stones, whose interior re- 

 mains wholly unchanged. Here and there, facts have been 

 observed which would seem to indicate a fusion together of 

 the meteoric fragments ; but, in general, the character of the 

 aggregate mass, the absence of compression by the fall, and 

 the inconsiderable degree of heat possessed by these bodies 

 when they reach the earth, are all opposed to the hypothesis 

 of the interior being in a state of fusion during their short 

 passage from the boundary of the atmosphere to our Earth. 



The chemical elements of which these meteoric masses 

 consist, and on which Berzelius has thrown so much light, 

 are the same as those distributed throughout the earth's 

 crust, and are fifteen in number, namely, iron, nickel, cobalt, 

 manganese, chromium, copper, arsenic, zinc, potash, soda, sul- 

 phur, phosphorus, and carbon, constituting altogether nearly 

 one third of all the known simple bodies. Notwithstanding 

 this similarly with the primary elements into which inorganic 

 bodies are chemically reducible, the aspect of aerolites, owing 

 to the mode in which their constituent parts are compounded, 

 presents, generally, some features foreign to our telluric rocks 

 and minerals. The pure native iron, which is almost always 



* The peculiar color of their crust was observed even as early as irj 

 the time of Pliny (ii., 56 and 58): "colore adusto." The phrase "lateri 

 bus pluisse" seems also to refer to the burned outer surface of aerolites 



* Humb., Rel Wst., t. ii., chap, xx., p. 299-302. 



