76 Dr. Walter Flight — History of Meteorites. 



The cavities, produced by the action of acid, are very small, about 

 0-005 mm. across, and have a rounded, sometimes quadratic, outline ; 

 the more perfect having- the form of rounded cubes. They are most 

 abundantly met with on the fillets alluded to above, those in the 

 same pieee of beam-iron being similarly orientated, and it is to them 

 and the parallel serration of the fillets that the crystalline damas- 

 kining is due. 



In the beam-iron are inclosed schreibersite and troilite, but graphite 

 was not observed. The schreibersite is only met with in this form 

 of iron, and occurs there in rounded particles and elongated forms, 

 which proceed from plates of this mineral, many of which lie parallel 

 to an octahedral face. It occurs very frequently round about the 

 remarkable lamellae of troilite (see infra) that lie parallel to the 

 faces of the cube. 



The fillet-iron (Bcmdeisen), or tanite, presents itself on the etched 

 surface in the form of prominent bands or fillets between the stripes 

 of beam-iron, and they are sections of lamellae lying parallel to 

 those of the beam-iron, — in other words, to the octahedral faces. 

 This form of iron, though in such thin plates, is found by the 

 microscope to be a fine tissue of heterogeneous substances. One 

 of these is nickel-iron, which coats the lamellae of tanite. A section 

 of this mineral is dull in appearance, but the boundary is brilliant ; 

 while outside it, lie brilliant points of not unfrequently regular form. 

 The framework and the points have the yellowish colour of nickel- 

 iron. The duller field, when strongly magnified, is seen to consist 

 of exceedingly fine plates of nickel-iron, which lie in two different 

 directions, for the lines intersect at 90°. The material lying between 

 these plates, which has been removed in greater abundance, is pure 

 iron. The lamellae of tanite are often penetrated and traversed by 

 fine plates of beam-iron. 



The interstitial iron (Fulleisen), which, as the name implies, 

 occupies the areas between the minerals already mentioned, is 

 abundantly present in masses sometimes extending to the breadth of 

 1 cm. It is made up of tanite and beam-iron, and is a representation 

 of the structure of the entire meteorite on a smaller scale, with such 

 modifications as seem to indicate that after the large lamellae of 

 beam-iron and tanite were already formed, the matter inclosed 

 between them became solid, and, shaping itself in accordance with the 

 same laws in a limited area, produced this variety of meteoric iron. 

 It occurs in two forms that vary but little from each other. In 

 one, fine stripes of beam-iron intersect, while between them is 

 tanite : this is an exact reproduction of the coarser structure of the 

 meteorite. In the other (and this is observed in the larger masses) 

 the square form is provided along its boundary with stripes of beam- 

 iron, the remainder appearing granular through a number of little 

 particles of beam-iron being ranged together with nickel-iron 

 between them. 



The occurrence of troilite in lamella? has been observed for the 

 first time in this iron. They lie parallel to the cubic faces, and, 

 unlike those of tanite, do not traverse any considerable portion of 



