38 0. C. Farrington — Action of Copper 



Art. IX. — The Action of Copper Sulphate upon Iron 

 Meteorites; by O. C. Farrington. 



In 1852 Wobler* announced the discovery that some iron 

 meteorites, irrespective of their nickel content or structure, are 

 passive to neutral solutions of copper sulphate, i. e., they do 

 not reduce copper from such a solution. This passivity he 

 stated could be overcome by introducing a piece of ordinary 

 iron into the solution or by adding a few drops of acid. 



No data were given as to temperature, length of time allowed 

 for deposition or the strength of the solution. The following 

 meteorites were reported by him to be passive : Bemdego, 

 Bohumilitz, Braunau, Cape of Good Hope, G-reen County 

 (undoubtedly Babb's Mill), Obernkirchen, the Pallas Iron, 

 lied River (probably Cross Timbers), Schwetz, Toluca, and 

 the terrestrial iron of Greenland. A number of other mete- 

 orites which need not here be enumerated he reported at the 

 same time as "active," i. e., they reduced copper from the 

 copper sulphate solution ; while those of a third class were 

 designated as "intermediate," i. e., they were nearly passive, but 

 after remaining some length of time in the solution brought 

 about a slow reduction of copper. That the passivity was a 

 property of the entire mass of the meteorite seemed to be 

 proved by the fact that when the surface of the meteorite had 

 been made active and the coating of copper was removed by 

 filing, it would again behave passive. 



Since the publication of Wohler's article several other 

 investigators of iron meteorites have tested their behavior 

 toward copper sulphate with the result usually of finding them 

 active, but the following, as listed by Cohen,f have been 

 reported passive : Toluca by Krantz, Knoxville by Smith, 

 Misteca by Bergemann, Octibbeha County by Taylor, Ohaba 

 by Bukeisen (this is a stone), Charcas by Meunier and Lexington 

 Co. by Shepard. Two of these, however, were reported by other 

 observers to be active, viz : Toluca by Pugh, Jordan and 

 Taylor, and Charcas by Daubree. The observers later than 

 Wohler also failed to give details regarding the conditions 

 of their experiments. Wicke and Wohler state that the 

 Obernkirchen meteorite, after remaining a day, reduced no 

 copper from its salts.:}: Smith states that Knoxville is passive 

 with reference to the action of sulphate of copper, but when 

 immersed in a solution of the latter and allowed to remain 

 several hours the copper deposits itself in spots on the surface 



* Poggendorff's Annalen 1852, vol. Ixxxv, pp. 448-9. 



f Meteoritenkimde, Heft 1, p. 68. 



i Ann. d. Chem. u. Pharm., 1864, vol. cxxix,, p. 123. 



