TRANSACTIONS OF THE SECTIONS. 55 



rhomboidal, tetrahedral, or in the figure of four-sided pyramids. It 

 required the application of numerous and powerfvd blows to disengage 

 fragments from the specimen. The hammer slightly indented the sur- 

 face, and at length loosened sections of the external laminae, which 

 were detached by the aid of forceps. Their shape Avas commonly that 

 of acute rhomboids, considerably flattened in their dimensions, but ca- 

 pable of an easy division into regular octohedrons and tetrahedrons, 

 whose exactness of form rivalled the cleavage crystals of fluor. Some 

 of the plates separated into leaves nearly as thin as mica, which sub- 

 stance they even resembled in colour, (being silver white, inclining to 

 steel grey,) and were slightly elastic, though when twisted up they re- 

 tained their spiral form. 



Prior to the separation of any fragments, the surface of the mass did 

 not afford the metallic lustre, but was coated by a thin blebby pellicle, 

 apparently of hydrous peroxide of iron. Those surfaces which were 

 exposed by cleavage lost their silvery grey lustre in the course of a 

 few weeks, and finally presented a rusty exterior, and even exfoliated 

 spontaneously, and separated into thinner layers and fragments. 



In specific gravity the fragments at first detached yielded various re- 

 sults, from 6-5 to 7"5, and even 8-0, — a diversity no doubt dependent 

 mainly on the compression of the fragments produced during their se- 

 paration from the mass. 



It was not until several days after Dr. Shepard commenced the che- 

 mical examination of the specimen, that it occurred to him that chlorine 

 might be an ingredient in its composition. Its existence, however, be- 

 came immediately apparent on the application of the usual test. Nor 

 was he less surprised on discovering, that after repeated digestions 

 of several hours at a time in aqua regia, a dark brown powder remain- 

 ed behind, which was no longer diminished in quantity by a continua- 

 tion of the process. It was separated from the solution, and ignited 

 with hydrate of potassa in a silver crucible ; water was then effused, 

 and the solution subsequently treated with nitric acid. A transparent 

 solution was instantly formed, from which ammonia threw down floc- 

 euli of silicic acid, coloured by peroxide of iron. A solution of potassa 

 was now added, and the peroxide of iron separated by the filter. The 

 clear liquid was rendered acid a second time, after which the addi- 

 tion of ammonia threw down white flocculi of silicic acid. 



It was in this way that Dr. Shepard satisfied himself of the existence 

 of silicon in the Ashville meteoric iron, which element, so far as he 

 was informed, had never before been noticed in an unoxygenated state 

 in any natural body, either meteoric or terrestrial. 



The following is a summary of the investigation in regard to this 

 meteoric iron : 



Iron .... 96-5 

 Nickel . . . .2-6 

 Silicon .... 0*5 

 Chlorine . . .0*2 



99-S, 



