Dr. Walter Flight— Eistory of Meteorites. 315 



dissolve any portion of the nickel-iron which by oxidation may 

 have been converted into hydrated oxide of iron and oxide of nickel. 

 To remove them von Baumhauer heats the powder, which has pre- 

 viously been treated with the chloride, in a current of hydrogen, 

 and, after reducing the oxides to the state of metal, subjects the 

 powder once or twice more to the action of the sublimate in an 

 atmosphere of hydrogen. By careful selection and treatment in the 

 above manner, he proceeded to operate on some apparently pure 

 olivine from the Pallas meteorite ; it was of a clear yellow colour, 

 and, when heated for half an hour in hydrogen, lost no weight. It 

 was then broken up with acid, and analysed by the usual method ; 

 the iron oxide retaining any nickel oxide that may be present was 

 twice dissolved in acid and thrown down with ammonia. The three 

 filtrates, containing all the magnesia, were treated with ammonium 

 sulphide, which produced a black precipitate, so small in quantity 

 that it could not be weighed. Before the blowpipe it displayed the 

 characteristics of a compound of nickel. 



Von Baumhauer expresses a doubt whether the nickel may not have 

 been a constituent of a trace of the metallic alloy which, in spite of 

 all precautions, may have adhered to the silicate. It is, moreover, a 

 question whether the repeated precipitation of the iron oxide with 

 ammonia, even in the presence of a large excess of ammonium 

 chloride, would effect the removal of a very small proportion of 

 nickel oxide in so complete a manner as Field's method with lead 

 oxide. 1 



In May, 1873, von Helmersen addressed a letter to Gr. Eose, 

 stating that several members of the Academy of Sciences of St. 

 Petersburg, Schmidt, Schrenck, von Kokscharow, himself and others, 

 had advised the Academy to institute an inquiry into the nature of 

 the ground of the locality where the Pallas siderolite was found, 

 they being of the opinion that such an investigation might throw 

 light on its history, just as an examination of the rocks of Disko 

 had proved of great value in facilitating the study of the Ovifak 

 meteorites. Lopatin, a mining engineer stationed in Eastern Siberia, 

 was directed to proceed to Krasnoyarsk for that purpose ; the result of 

 his explorations has apparently not yet been published. According 

 to Mettich's report, a very rich iron ore is found on the hill and 

 close to the spot where the Pallas siderolite was discovered. 



The Mexican Meteorites. 3 



In continuation of his earlier papers on the meteorites of the 

 Mexican Eepublic, which appeared in 1856, 1857, and 1858, the late 

 Dr. Burkart has brought the history of these remarkable masses 

 down to the date 1874. He first directs attention to the masses 



1 F. Field. Chem. News, i. 4. 



2 C. Kammelsberg. Zeitsch. Deutsch. Geol. Gesell., 1869, xxi., 83.— J. L. Smith. 

 Amer. Jour. Sc, 1869, xlvii., 383; Amer. Jour. Sc, 1871, i. 335.— S. Meunier. 

 These presentee a la Faculte des Sciences de Paris, 1869. Recherches sur la com- 

 position et la structure des Meteorites, 42 et sea. — H. J. Burkart. Jahrb. Mineralogie, 

 1870, 673 ; 1871, 851 ; and 1874, 22. 



