408 Dr. Walter Flight — History of Meteorites. 



The soluble part is an olivine of the same composition, 3 Mg 2 SiO 

 4- Fe 2 Si0 4 , as that met with in the meteorites of Hainholz, Borkut, 

 St. Mesmin, Muddoor, Shergotty, etc. ; the insoluble portion appears to 

 be a bronzite, in which the bases Ca : Fe : Mg=l : 3 : 9, accord with 

 those of the variety of this mineral which occurs in the Chantonnay 

 stone. The Mezo-Madaraz meteorite therefore belongs to the large 

 class of chondritic masses above mentioned. 



1852, December 2nd. — Busti, between Goruckpur and Fyzabad, 

 India. [Lat. 26° 45' N. ; Long. 82° 42' E.] 1 



With a view to obtain some more satisfactory means of dealing 

 with the aggregates of mixed and minute minerals, which constitute 

 meteoric rock, the author sought the aid of the microscope, having 

 in the first place sections of small fragments cut from the meteorites 

 so as to be transparent. By studying and comparing such sections 

 one learns that a meteorite has passed through changes, and that it 

 has had a history of which some of the facts are written in legible 

 characters on the meteorite itself; and one finds that it is not difficult 

 roughly to classify meteorites according to the vai'ieties of their 

 structure. One also recognizes constantly recurring minerals ; but 

 the method affords no means of determining what these are. Even 

 the employment of polarized light, so invaluable where a crystal of 

 which the crystallographic orientation is at all known is examined 

 with it, fails, except in rare cases, to indicate with certainty even the 

 system to which such minute crystals belong. It was found that the 

 only satisfactory way of dealing with the problem was by employing 

 the microscope, chiefly as a means of selecting and assorting out of 

 the bruised debris of a part of a meteorite the various minerals that 

 compose it, and then investigating each separately by means of the 

 goniometer and by analysis — finally recurring to the microscopic 

 sections to identify and recognize the minerals so investigated. In 

 the memoir mentioned below the author publishes the results of the 

 former part of this inquiry. It is obvious that the amount of each 

 mineral which can be so obtained is necessarily small, as only very 

 small amounts of the meteorite could be spared for the purpose. On 

 this account one has to operate with the greatest caution in perform- 

 ing the analysis of such minerals, and the desirableness of determining 

 the silica with more precision than usually is the case in operations 

 on such minute quantities of a silicate suggested a process which, 

 after several experiments had been conducted with a view to perfect- 

 ing it, assumed a definite form. The method, which essentially 

 consists in the separation of the silicic acid from the bases by dis- 

 tillation with hydrofluoric acid, whereby the operator is enabled to 

 proceed to the estimation of the whole of the constituents of any 

 silicate in one and the same portion, will be described in detail 

 later on with other new methods of analysis. 



1 N. Story-Maskelyne. Proc. Royal Society, xviii. 146. Philosophical Trans- 

 actions, clx. 189. (See also Abstract in Nature, i. 382.) — A preliminary notice of 

 this meteorite appeared in the Brit. Assoc. Report, 1862, "Notices and Abstracts." 

 Appendix ii. 190. 



