COMPOSITION AND STRrCTURE OF METEORITES 17 



Avej-age composition of stony meteorites 



Constituent : Per cent 



Silica (SiO^) 38. 41 



Titanic oxide (TiOj) .16 



Tin oxide (SnOa) 



Zirconium oxide (ZrOa) 



Alumina ( AI2O3) -■ 2. 86 



Ferric oxide (Fe203) .92 



Chromic oxide (Cr203) . 40 



Vanadium oxide (V2O3) 



Metallic iron (Fe) 12. 35 



Metallic nickel (Ni) -.^ 1. 09 



Metallic cobalt (Co) . 10 



Ferrous oxide (FeO) 13. 60 



Nickel oxide (NiO) . 40 



Cobalt oxide (CoO) . 06 



Lime (CaO) 1. 88 



Barium oxide ( BaO) 



Magnesia (MgO) 23. 66 



Manganous oxide (MnO) . 23 



Strontium oxide (SrO) 



Soda (NajO) . 82 



Potash (K2O) . 16 



Lithia (Li20) 



Ignition (H2O) . 47 



Phosphoric acid (P2O5) . 34 



Sulphur (S) 1. 89 



Copper (Cu) . 01 



Carbon (C) . 16 



Chlorine (Cl) . 03 



100. 00 

 EXTERNAL AND INTERNAL FEATURES OF METEORITES 



There are certain external features characteristic of nearly ail 

 meteorites, both stones and irons, which may well be considered 

 before entering upon a detailed discussion of internal structures. 



Apparently there is no necessary limit to the size of meteorites, 

 though the largest actually known is the giant brought by Commander 

 Peary from Cape York, in Greenland, which weighed 37}^ tons. 

 The smallest stone, constituting all that is Icnown of the fall is that 

 of Mulau, Austria, which weighed but 5 grams. It is now pretty 

 generally conceded that meteorites, of whatever type or size, are 

 fragments at the time they enter our atmosphere, and that as a rule 

 a further fragmentation and reduction in size takes place owing to 

 the atmospheric pressure induced by the enormous speed at which 

 the body may be traveling. Iron being tougher and more resistant 

 than stone, it would naturally follow that among the metallic forms 

 giants, if such there are, would prevail. This idea is fully borne out 

 in fact, and attention need but be called to the frequent occurrence 

 of stone "showers" and their rarity among irons. The form and 



