On a Mass of Meteoric Iron. 



403 



its longest diameter. Its hardness, as shown by a graving 

 tool, was greatest next its outer surface — the inner portions 

 being apparently softer, and more open in texture, while the 

 prism-like point was tougher before the tool, and more like 

 hammered iron ; the explanation probably being — that this 

 peculiarity was due to the shock of the fall being given prin- 

 cipally to this part of the mass ; and also, to its being sud- 

 denly cooled by the contact of its surface with the earth in 

 which it was found buried. 



The filings, of which about a troy ounce were procured, 

 were black, and showed little of the shining metallic appear- 

 ance of pure iron. 



Chemical Analysis. — The filings were sent for examina- 

 tion to Dr Murray Thomson, who gives details of their com- 

 position in his subsequent communication. (See Analysis of 

 Meteorolite, by Dr Murray Thomson.) 



Test of Etching by Acid. — Each portion of the iron has 

 been partially etched with the acid used by engravers on steel, 

 which consists of equal parts of nitric and acetic acids ; and 

 the etched surfaces show the rough, irregular, projecting lines 

 of the crystalline structure of the mass, which have been 

 apparently but slightly acted on by the acid, from the pre- 

 sence of nickel ; the dark lines and spaces showing where the 

 acid has acted with greater effect. The acid was applied in 

 •the usual way for etching, and appeared to bite all at once, 

 and that pretty deeply ; it was then removed, the surface of 

 the metal washed, and the acid reapplied, when it acted very 

 slightly, and soon ceased to act altogether, not biting any 

 deeper into the surface of the metal. The rough etched sur- 

 face is characteristic of meteoric iron, various bright lines or 

 points being observed in the fine frosted like appearance of 

 the crystalline or fibrous surface of the metal. This etched 

 surface is finer and more minute in its texture than that of 

 any meteoric irons, the etchings of which I have been able 

 to examine, suggesting a more minute subdivision of the 

 particles of the iron and nickel, and a more general mixture 

 of the nickel through the mass.* 



* Mr 11. P. Greg of Manchester informs me this minute texture resembles 

 the structure of the iron also found in Britain, and described by him, — more 



