352 franklin county (ky.) meteoric iron. 



2. On the Presence of Cobalt in Meteoric Irons. 



My attention has been directed again and again to meteoric 

 irons whose analyses are given without mention of the presence 

 of cobalt; and in some instances with the distinct statement 

 that it is absent, as in the recent examination of a meteoric 

 iron from Auburn, Macon County, Alabama, by Prof. Shepard, 

 who states that "neither cobalt, tin, nor copper was detected 

 in this iron." I can not but suggest the importance of making 

 a most critical examination of these irons before pronouncing 

 this fact; for in every analysis that I have made of meteoric 

 irons (over one hundred different specimens) with this in view, 

 cobalt has been invariably found, along with a minute quantity 

 of copper. A great many of the analyses made were of irons 

 that had been previously examined without a recognition of 

 the cobalt. 



The presence of these ingredients, even in small quantities, 

 is a matter of considerable mineralogical interest, as is the case 

 of the presence of small quantities of other elements in many 

 minerals ; a fact that I will have occasion to refer to at some 

 future time in connection with leucite and other silicates. 



As a guide to those who may wish to know the manner of 

 my examinaton of meteoric iron, I will give a little in detail 

 the method adopted in separating the metals. 



Method of analysis. — A small piece of the iron is selected 

 perfectly free from crust and earthy matter. I sometimes 

 plunge the fragment into nitric acid somewhat diluted, warm 

 the acid and continue the action for a few seconds, withdraw 

 the iron, wash well and dry it. The piece selected for analysis 

 should be about one gramme, or a little over (except where the 

 copper is sought for quantitively, and then at least ten "grammes 

 should be used for the copper estimate alone). Treat the iron 

 in a porcelain capsule, or glass flask, with a mixture of hydro- 

 chloric and nitric acids, consisting of four parts of the former 

 to one of the latter, and about as much water as acid; dissolve 

 over a water-bath. If a capsule be used, invert a funnel over 

 the mixture, the edges of the funnel entering the capsule but 

 not touching the mixture. Continue the action on the water- 

 bath until the solution is complete ; evaporate to dryness (having 

 washed what may adhere to the inner surface of the funnel into 



