8 PROCEEDINGS OF THE NATIONAL MUSEUM vol. 72 



oxide prepared by the precipitation of the iron of solutions of 

 meteoric iron. These results were summarized as follows : 



1. The artificial hydroxide of iron, prepared from pure iron and 

 dried at low temperatures, is attracted feebly by the hand magnet, 

 but loses this property at and below red heat. 



2. Ferric oxide, prepared in the ordinary manner, from solutions 

 of meteoric iron and dried at a low temperature, acts similarly to the 

 ordinary oxide, but becomes decidedly magnetic on being heated from 

 400° C. to a red heat. 



3. The ferric oxide from ordinary iron, mixed with nickel or cobalt 

 or both, from whatever source, exhibits magnetic properties identical 

 with that from meteoric iron. 



4. Ferric oxide from meteoric iron, freed entirely from traces of 

 nickel and cobalt, corresponds to the ordinary ferric oxide in its 

 behavior to the magnet. 



5. Ferric oxide made from iron mixed with copper resembles that 

 irom meteoric iron. 



6. Ferric oxide made from iron mixed with manganese, gold, plati- 

 num, zinc, or calcium differs in no way from the pure ferric oxide in 

 its behavior to the magnet. 



By reducing the oxides in hydrogen and analyzing the resultant 

 metal. Smith found 2 or 3 per cent of cobalt, nickel, or copper in 

 the magnetic oxides, and he expresses the opinion that these in some 

 manner act to reduce a small part of the ferric iron to magnetic oxide. 

 Only in a footnote does he mention that it has been suggested to 

 him by Prof. F. C. Chandler that the nickel, cobalt, and copper oxides 

 present may form, with ferric oxide, a magnetic oxide as NiO.FeaOg, 

 analogous to FeO.FegOg. 



It is clear that the magnetic character of the ignited oxides is due to 

 the formation of f errites. In the analysis of meteoric irons it is very 

 difficult to quantitatively separate the nickel and cobalt by precipi- 

 tation of the iron with ammonia even when the precipitation is 

 repeated several times. With a single precipitation the nickel is 

 largely held by the precipitate, and it is not uncommon to find more 

 nickel in the second ammoniacal filtrate than in the first. 



Artificially prepared ferrites of copper, nickel, and cobalt have 

 been found to be strongly ferromagnetic® while the analogous fer- 

 rites of K^O, Na,0, Cu^O, CaO, BaO, MgO, ZnO, and PbO were 

 nonmagnetic. 



Natural and relatively pure nickel ferrite of terrestrial origin 

 from South Africa has been recently described by Crosse ® and 



* S. Hilpert and P. Beyer. Tiber eisenoxydulosyde und eisenoxyde. Ber. Deut. Chem. 

 Oes., vol. 42, pt. 4, 1909, pp. 4893-4895. 



^A. F. Crosse. A rich nickel ore. Joiirn. Chem Met. and Mining Society of South 

 Africa, vol. 21, p. 126, 1921. 



