168 REPORT — 1876. 



Part II.' — Accounts of Aerolites and Aerolitic Meteors, and Abstracts of 

 recent Eesearches on them. By W. FiiaHx. 



1875, Pebruaiy 12th, 10.30 p.m. (Chicago time). — Iowa Co., State of Iowa*. 



The conclusions arrived at by Wright, on examining the gases occluded by 

 the iron of these meteorites, have been referred to in the Iteport (B.A.) for 

 1875, p. 240. He considered that the stony meteorites were distinguished 

 from the iron ones by having the oxides of carbon, chiefly the dioxide, as 

 their characteristic gases instead of hydrogen. This theory has been called 

 in question by Mallet, who refers to his examination of the gases of the iron 

 of Augusta Co., Yirginia, where the ratio of the oxides of carbon to hydrogen 

 is 4 : 3, and to his having pointed out in 1872 that hydrogen could no longer 

 be regarded as the characteristic gaseous ingredient of meteoric iron. In his 

 paper of that date he stated that although it might be assumed that carbonic 

 oxide would be the original form in which the gaseous carbon-compounds 

 existed in the iron, and that it lirokc up at the temperature of the experiment 

 into carbon retained by the iron and into carbonic acid, yet in view of the 

 steady decrease of the quantity of the latter gas which was evolved as the 

 experiment proceeded, it seems more likely that a larger amount of carbon 

 originally existed in the higher state of oxidation. Mallet considers that, 

 when all the circumstances of the experiment are considered in each case, 

 Wright's conclusion cannot be sustained. 



In a paper dated some months later, Wright replies to Mallet's criticism. 

 He states that he only meant this expression of opinion to be tentative, Init 

 that the results of further work completely justify the conclusion at which 

 he had arrived. He has re-examined the gases of the iron of this meteorite, 

 and examined those of the iron of some other stony meteorites, such as Ohio, 

 • Tultusk, Parnallee, and Weston, and finds that not only do the stony mete- 

 orites give off a much larger volume of gas at low temperatures, but the 

 composition of the gas in all the cases studied is quite different from that 

 evolved from meteoric iron. In no case among the results obtained with the 

 alloy is the amount of carbonic acid greater than 20 per cent, at 500°, nor 

 than 15 per cent, of the A^hole quantity evolved, while in every case but 

 one the volume of carbonic oxide is considerably larger. In the chondritic 

 meteorites, on the other hand, the percentage of the latter gas is conspicuously 

 small, while the carbonic acid constitutes more than half the total gas evolved 

 below a red heat, except in the case of the meteorite under consideration 

 which fell at Iowa, and here the percentage is not much less, especially if we 

 reject the numbers representing the amount obtained by a second and long- 

 continued application of a red heat. At a temperature of about 350° it 

 constitutes from 80 to 90 per cent, of the gaseous products, and at 90° it 

 forms more than 90 per cent, of the gas evolved. The hydrogen, on the 

 other hand, progressively increases in quantity with the rise of temperature, 

 and is the most important constituent of the first portions removed at a red 

 heat. The form in which the carbonic acid is occluded is a problem which 

 he cannot at present solve. That it is actually absorbed appears to be certain. 



* J. W. Mallet, ' Amer. Journ. Sc' 1S7.5, rol. x. p. 206 ; N. E. Leonard, ib. vol. x. 

 p. 367; A. W. Wright, 'Amer. Journ. So.' 1876, vol. xi. p. 253; "An Account of the 

 Detonating Meteor of February 12, 1875," by C. W. Iri.sli, Iowa City, 1875, Daily Pres.s 

 Job Printing Office, Dubuque Street; M. Delafontaine, Bibliotheque Universelle,' October 

 1875, p. 188; G. A. Daubree, ' L'Institut,' 1875 (Nos. 105-122), p. 138; C. W. Giimbel, 

 ' Sjtzungsber. Ak. Wiss. Muncben,' 1875, vol. v. p. 313. 



