ART. 21 OXIDATION OF METEORIC lEONS SHANNON 6 



Second. Does such magnetite, if formed, further oxidize to anhy- 

 drous ferric oxide of ferromagnetic character? 



Third. Were there formed any nickel or other analogues of magne- 

 tite of the type of trevorite (NiO.Fe203) in the process of oxidation? 



Fourth. Could a second ferromagnetic ferric oxide similar in 

 atomic grouping or space lattice to metallic iron be formed without 

 the intermediate formation of magnetite through the oxidation of 

 crystalline metallic iron ? 



Fifth. Could intermediate stages of ferrous chloride (lawrencite) 

 or of ferric chloride (molysite) influence the space lattice or the mag- 

 netic properties of the oxide formed ? 



Sixth. Do terrestrial examples, as known, compare with iron 

 meteorites in the nature of their oxidation products ? 



SUMMARY OF CONCLUSIONS 



The results attained and the conclusions deduced therefrom may, 

 in brief, be tabulated as answers to the above queries : 



First. Magnetite forms only in relatively small amounts as a 

 transitory and unstable stage in the oxidation. 



Second. The magnetite and the iron itself rapidly change to 

 limonite or ferric hydrate without the intervention of appreciable 

 amounts of ferromagnetic ferric oxide. 



Third. The formation of trevorite (NiO.FcaOg) and of analogous 

 compounds of cobalt and copper — persistent ferrites — seems to be 

 established and that these are strongly ferromagnetic and account for 

 the m.agnetic properties of the whole. 



Fourth. There is no evidence in support of the assumption that 

 any ferromagnetic oxide of any kind is formed except the ferrites 

 of bivalent oxides above mentioned. 



Fifth. Owing to the lack of evidence and the unstable nature and 

 deliquescent character of the chlorides it is doubtful that they have 

 any action other than to promote the formation of amorphous hy- 

 drated ferric oxide from the iron. 



Sixth. The terrestrial occurrences of ferromagnetic ferric oxide 

 are different in composition and origin and present no analogies to 

 the oxidation of meteorites. 



ACKNOWLEDGMENTS 



The writer is indebted to Doctor Merrill for the free use of mate- 

 rial and data and for the time and opportunity to prosecute the pres- 

 ent investigation. To Dr. Eugene Posnjak he is indebted for free 

 discussion and advice regarding the points involved and to Mr. For- 

 rest A. Gonyer for much valuable assistance in the preparation and 

 analysis of the samples studied. 



