32 



PROCEEDINGS OF THE AMERICAN ACADEMY 



diagram, that all the lines follow the intersections of the different 

 members of an ordinary cube twinned on all of the trigonal axes, and 



Secointi. ivi I 

 impurtivicej 



Most pro-~| 



Fig. 4. 



there were no markings on the face which could not be thus referred. 

 However, on examining the triangular face D of Fig. 2, it appeared 

 in marked contrast to the face just described, as all the markings were 

 parallel to the octahedral edges, thus forming simple triangles. 



A large number of specimens of the Butcher iron were afterwards 

 examined, and they all exhibited the same crystalline cleavage on a 

 fresh fracture. Moreover, it made no difference in what direction the 

 slab was broken, the planes always showed a prevalence of the 132° 

 angle (theoretical angle 131° 48' 37"), with here and there the sharp 

 projecting points already referred to, but, contrary to expectation, the 

 simple cube angles seldom appeared, though in some parts they were 

 evident. 



It now appeared important to examine the cleavage of the Sancha 

 Estate or Saltillo iron (Santa Rosa), which has been considered part 

 of the same meteorite as the Butcher specimens. For this purpose 

 Mr. S. C. H. Bailey sent us a wedge-shaped slab which had been 

 sawed to a thin edge and then broken, giving a surface of fracture 

 about seventy millimeters long and two millimeters wide in the thick- 

 est part, diminishing towards the two ends. The crystal faces over 

 this surface were very small, and appeared to have a grayer color than 

 those of the other irons. When this surface was examined under a 

 low power microscope, the crystals were found to be all simple cubes, 

 looking exactly like a specimen of galena, and, instead of the faces 

 being striated as in the Butcher irons, they exhibited the little crys- 

 talline projections and depressions which are so characteristic of some 

 alloys. However, on the face of the slab there was the suggestion of 

 two cracks crossing at angles of about 132° and 53°, and an attemnt 



