SIZE, WEIGHT, AND SURFACES 99 



convex, and in one plane (that of the minor axia and the normal) is 

 distinctly concave. 



Weight and specific Gravity 



When brought to the university, the Algoma iron weighed a little less 

 than 9 pounds, or somewhat more than 2 kilograms (weighed with a 

 spring balance). A small slice, in the widest place less than 3 centi- 

 meters in width, was sawed from one end, and due to a misunderstand- 

 ing of instructions a saw-cut was made, running partly through the 

 meteorite at a greater distance from the end (see plate 4). After suffer- 

 ing these losses the main meteorite mass now weighs 3,716 grams. 



A block weighing a little over 39 grams, polished on two sides, after 

 boiling in water for half an hour and cooling to room temperature, was 

 weighed in the water, and then, after drying, in air by the suspension 

 method. The result obtained for the specific gravity was 7.75. 



Surfaces 



the con vex s vrfa ce 



Larger irregularities — The convex surface, for reasons which will ap- 

 pear, designated the front of the meteorite {Bruslseite) , merits a careful 

 consideration. Marks which this surface owes to its maltreatment sub- 

 sequent to its discovery in 1887 are the dents (art, figure 1) from pound- 

 ing with a sharp rock edge, the grooves (6 6, figure 1, and c c, figure 2), 

 from attack with a cold chisel and hammer, and the abraded surface 

 (c, figure 1) and scratches (rf, figure 1) which are the work of a file. In 

 addition to these disfigurements there are larger surface features of two 

 kinds. At e and /(figure 1) and less prominent at g are relatively deep 

 pits of markedly irregular outline which doubtless owe their origin to 

 the fusion and removal of a mineral (schreibersite) more fusible than 

 the nickel-iron itself. The manner in which such pits are formed is 

 well illustrated by the small pitting cut through by the saw and shown 

 in plate 7, figure 1, at the bottom of which may be seen the schrei^ 

 bersite crystals separated by walls of swathing kamacite. The pit at e 

 (figure 1) corresponds in position with a similar pit upon the back of 

 the meteorite (6, figure 2), and doubtless was once continuous through 

 the disc, as it may now be followed nearly through and appears to be 

 choked for a short distance by the oxide scale which lines its walls. 



The low fusibility of schriebersite is well known and was well brought 

 out during the polishing of the section, the smaller crystals of schreiber- 



