230 PROCEEDINGS OF THE AMERICAN ACADEMY 



must have formed the crust of the original mass, appears quite 

 smooth except for a succession of small pittings, in the centre of each 

 of which appears a little drop of chloride of iron, making it rust rap- 

 idly, and so causing little scales to flake off, thus possibly producing 

 the depressions. This surface is the one shown in Figure 1. On the 

 other hand, the concave side of the specimen is characterized by a 

 vesicular structure not unlike certain furnace specimens, some of the 

 cavities being about two centimeters across and nearly as deep. 

 These cavities seem to be distributed with some regularity in three 

 more or less parallel zones across the shorter dimension of the 

 surface. Figure 2 is intended to show this feature of the specimen. 

 These cavities appear to have no connection with the pittings of the 

 surface, and are different from anything I have observed in the 

 meteoric irons which have come under my notice. They seem to 

 suggest an evolution of gas 'from the material in process of cooling, 

 which may have been the cause of the splitting off of the specimen 

 from the original mass. 



In order to examine the structure, the iron was sawed through the 

 thickest part by means of a toothless band saw fed with emery ; but 

 when the cut had come within an inch of the opposite edge, the remain- 

 ing portion was forcibly broken in order to bring out the characters of 

 the fracture, when the iron showed a somewhat new feature. The metal 

 was so malleable, that, though the connecting surface had an area of a 

 square inch, the two portions could be bent and twisted quite readily, 

 almost like masses of lead, but it was very difficult to make it break ; 

 and when at last the two portions sepai'ated, the fracture showed 

 no crystalline structure whatever, but only irregularly curved surfaces 

 like a perfectly plastic material. 



The author has shown in a previous paper,* that even the most 

 malleable meteoric irons, when broken under the hammer, usually 

 exhibit very striking peculiarities of cleavage parallel to certain 

 crystalline faces, and that even in such compact irons as those of 

 Bates County and Coahuila large cleavage crystals could be broken 

 out from the mass ; and the characters exhibited by the cleavage were 

 suggested as a possible means of distinguishing different meteoric 

 irons where other methods proved insufficient. Hence the fracture 

 of the Stutsman County iron was a complete surprise, and in order to 

 study it further it was mounted in the vice and broken in various 

 directions, but no trace of cleavage could be produced. When the 



* These Proceedings, vol. xxi. p. 478, May 12, 1886. 



