530 STUDIES FOR STUDENTS 



on evaporation of the water extract a residue of soluble salts 

 reaching in quantity in one case as high as lo per cent, of the 

 mass. These salts include nickel, calcium, magnesium, potas- 

 sium, sodium and ammonium sulphates and chlorides. 



Since the meteorites in which they occur are ver}^ porous in 

 character and show other signs of alteration these compounds 

 are usually considered to be formed by terrestrial modification 

 of the meteorite and not to exist as original constituents. Dau- 

 bree, however, gives good reasons for regarding the sodium 

 chloride which he found in the Lance meteorite an original con- 

 stituent. These reasons are that the meteorite had lain only 

 three days in a clayey bed before it was picked up and no salt 

 is known to have come near it. Breiinnerite . This mineral was 

 found in the meteorite of Orgueil occurring in the form of little 

 transparent crystals. The identity of the mineral was estab- 

 lished both by qualitative tests and by goniometric measure- 

 ments. It has been suggested that it was of secondary origin. 

 As it was found well within the interior of some masses, this, 

 however, hardly seems likely. This is the only carbonate known 

 from meteorites. 



A number of other minerals have been reported from meteor- 

 ites without sufficient grounds, according to the writer's view, to 

 support the conclusion. Cohen considers them doubtful while 

 Meunier accepts most of them. These are : Apatite, iolite, 

 wollastonite , tita?iite, garnet, vesuvia?iite, mica, aragonite, leiicite, cas- 

 siterite, hornblejide , anthopliyllite and orthoclase. 



Mineral aggregates. — The different aggregates which the com- 

 pounds above described form in different meteorites are too 

 various to be recorded here in detail. For an account of 

 these, reference should be made to the elaborate classifications 

 of Meunier,^ Brezina^ or Wi.ilfing.3 



A few general observations may be made here, however, 

 following the lines of the classification given by Wiilfing. The 



' Revision des Pierres Meteoriques. Paris, 1897. 



^Annalendes k. k. Naturhistorischen Hofmuseums. Bd. X, Heft 3 u. 4. Vienna, 

 1896. 



3 Die Meteoriten in Sammlungen. Tubingen, 1897, pp. 447-460. 



