354 FRANKLIN COUNTY (KY.) METEORIC IRON. 



iron, which I have every reason to believe was originally for- 

 eign to the iron. 



The sulphureted hydrogen precipitate, which I have always 

 obtained, is so minute in a gramme of iron that it may be dis- 

 pensed with, and the iron, nickel, and cobalt be separated, which 

 is accomplished as described a little further on. If, however, 

 sulphureted hydrogen has been used, the iron in solution is in 

 the form of protoxide, and must be converted into the peroxide, 

 which is accomplished by adding a little chlorate of potash and 

 hydrochloric acid, that have been made to react on each other 

 by heating, before adding it to the boiling solution of iron, etc. 



The solution of iron should have a bulk of ten or twelve 

 ounces ; to it is added a solution of carbonate of soda in suffi- 

 cient quantity to nearly neutralize the free acid; the iron is 

 now precipitated by acetate of soda with all the well-known 

 precautions. I wash this precipitate only partially, and detach 

 it from the filter by washing it into a beaker and re-dissolving 

 it by hydrochloric acid, and precipitate it a second time by ace- 

 tate of soda; I then subject it to complete washing, and estimate 

 the iron in the way usually employed. This second precipitation 

 is necessary to separate an appreciable quantity of nickel remain- 

 ing in the acetate of iron after the first precipitation ; and after 

 considerable experience I must say that it is the only method 

 of separating with any degree of accuracy iron from nickel. 



The solution separated from the iron, and containing nickel 

 and cobalt, is concentrated down to four or five ounces, then 

 treated with caustic potash or soda, thrown on a filter and 

 washed with hot water, with all the usual precautions when 

 nickel is precipitated by an alkali. The precipitate is dried, 

 ignited and weighed ; after which it is dissolved in nitric acid 

 over a water-bath and the acid solution evaporated nearly to 

 dryness ; about two or three drachms of water are added, then 

 a concentrated solution of nitrite of potash, then an excess of 

 acetic acid; this is now set aside for forty-eight hours, during 

 which time the nitrite of cobalt is completely separated ; it is 

 next thrown on a filter, washed and estimated in the manner 

 proposed by the author of this method. I usually employ a 

 concentrated solution of the sulphate of potash to wash with. 

 This method, to say the least of it, has in my experience proved 

 fully equal to the cyanide method, and is much more simple; 



