66 THE SIDEROLITES AND PALLASITES. 



" Chemistry has entirely dissipated all doubts in the matter, and now an examination 

 in the laboratory of the chemist is entitled to more credit than evidence from any other 

 source in pronouncing on the meteoric origin of a body. No question need be asked as 

 to whether it was seen to fall, or whether this or that rock or mineral exists in the neigh- 

 borhood where it may have been collected. The reagents of the chemist alone are uner- 

 ring indications tliat suthce to set aside all caviUing in the matter." * 



The above statement rests upon the assumption that no terrestrial ma- 

 terial under any circumstances can possess the same chemical characters 

 that meteorites do ! This basis is the one upon which most investigations 

 of supposed meteoric irons now proceed, and have proceeded for many 

 years ; f a basis that has never been carefully investigated, and which 

 many would probably repudiate since the Ovifak discovery. Would it not 

 be well if a more thorough study could be made of the conditions under 

 which so many siderolites have been found in the southwestern portion of 

 the United States, Mexico, and South America ? 



The origin of the meteoric masses of iron has been a question upon which 

 speculation has been rife. It has been suggested that they and tlie other 

 meteorites were formed in our own atmosphere ; that they were thrown 

 from terrestrial or lunar volcanoes ; or thrown from the sun ; the remains 

 of a shattered jDlanet ; some of the spare material left over when the solar 

 system was made. etc. It concerns this work jDrincipally to examine the 

 views of those who have made microscopical studies of siderolites, and not 

 to discuss the general theories of others ; however, it will be necessary later 

 to point out the probable origin of meteorites as deduced from their micro- 

 scopic characters. One of the most prominent of the students of meteor- 

 ites is Professor Gustav Tschermak, who stated in 1875 that 



" the greater number of meteoric irons exhibit a structure which indicates that each has 

 formed part of a large mass possessing similar crystalline cliaracters. The formation of 

 large masses so constituted presupposes, as Haidinger has pointed out, long intervals of 

 time for tranc[uil crystallization at a uniform temperature, and these conditions could 

 only prevail on one of the larger cosmicai masses." :|: 



A microscopic examination of the figures observed upon the etched sur- 

 face of meteoric and artificial irons, led Mr. Sorby to the following con- 

 clusions : — 



" Tliese facts clearly indicate that the Widmanstatt's figuring is the result of such a 

 complete separation of the constituents, and perfect crystallization, as can occur only when 



* J. Lawrence Sniitli's Mineralogy and Chemistry, Louisville, Ky., 1873, p. 290. 

 t Newcomb's Astronomy, 1st ed., 1878, p. 386 ; 4th ed. 1882, p. 397. 



t Phil. Mag., 1876 (5), i. 499 ; Sitz. Wien. Akad., 1875, l.xxi. (2), 661-673. See also J. Lawrence 

 Smith's Memoir on Meteorites, Ann. Kep. Smith. List., 1855, p. 158. 



