404 Dr. Walter Flight — History of Meteorites. 



1847, February 25th.— Hartford, Linn Co., Iowa. 1 



This meteorite was originally examined by Sbepard (Report on 

 American Meteorites, 1848, page 37), who states that it consists of 

 83 per cent, of a silicate to which he gives the name of ' howardite ' 

 (an iron-magnesium silicate with the oxygen ratio of EO : Si0 2 =l : 

 3-3), about 10 per cent, of nickel-iron and 5 per cent, of magnetic 

 pyrites. Shepard moreover asserts in his paper that this extremely 

 acid silieate fuses easily before the blowpipe, and gelatinises with 

 warm dilute acid. Not a little astonished that a silicate of this form 

 should possess such properties, Eammelsberg undertook an examin- 

 ation of this meteorite, which he finds to possess the following 

 composition : 



Nickel-iron 10-54 



Troilite 6-37 



Soluble silicate ... ... 41-85 



Insoluble silicate .... 41-24 





Si0 3 



A1 2 3 



FeO 



MgO 



A. Soluble ., 



,.38-80 



— 



21-31 



39-89 



B. Insoluble 



..55-08 



4-86 



13-58 



22-70 



100-00 

 The nickel-iron alloy consists of 



Iron= 89-75; nickel = 10-25 ; Total = 100-00. 

 and the composition of the two portions of silicate separated by the 

 action of acid and sodium carbonate was as follows : 



CaO Na 2 K,0 



— — — = 100-00 



2-85 0-93 trace = 100-00 



The oxygen per-centages of A clearly indicate the presence of an 

 olivine in which the ratio of Mg : Fe is 3:1, or the same as that of 

 the variety of this silicate which occurs in the Hainholz siderolite. 

 The insoluble portion, about equal in amount to the above, appears 

 to consist of a bronzite (or bronzite mixed with a little augite), in 

 which Mg : Fe : Ca is as 12 : 4 : 1 ; the ratio of iron to magnesium in 

 the two minerals forming the chief Ingredients of this meteorite is 

 therefore the same. Eammelsberg's results differ altogether from 

 those given by Shepard, and indicate the presence in this stone of 

 those minerals only which are frequently met with in meteorites. 

 ' Howardite ' has not been identified as a mineral species in any rock, 

 terrestrial or meteoric. 



1847, July 14th. — Braunau (Hauptmannsdorf and Ziegelshlag), 



Bohemia. 2 



In a memoir on the crystalline characters of iron, and especially 

 of meteoric iron, Tschermak describes the structure of the specimens 

 of Braunau iron preserved in the Vienna Collection. One piece 

 exhibits the cleavage planes of the cube, as well as other smaller 

 faces on the edges and corners of the cube ; the angles which these 

 faces form with those of the cube are 70° and 48 , corresponding 

 evidently with those enclosed between the faces of the triakis- 



1 C. Eammelsberg. Monatsber. Ah. Wiss. Berlin, 1870, lxx. 457. 



2 G. Tschermak. Sitzber. Ah. Wiss. Wien, 1874, Nov.-Heft, lxx. 



