FRANKLIN COUNTY (KY.) METEORIC IRON. 353 



the capsule), then add a little more hydrochloric acid and evapo- 

 rate again nearly to dryness. This is done to insure driving off 

 the last portion of nitric acid and rendering the iron easily 

 soluble. Add to the contents of the capsule an ounce or two 

 of water, and if there be a residue it must be collected on a 

 weighed filter, dried, weighed, and reserved for future examina- 

 tion; if the quantity be too small for examination, a larger 

 portion of the iron must be examined with special reference to 

 this residue — which most commonly is a silicate, but may con- 

 tain carbon or chromic iron (chromite). 



If, however, there is no residue, proceed to the next step 

 at once without filtering; if the solution has been filtered the 

 following steps are the same. Examine first for sulphur. This 

 is done by adding a few drops of chloride of barium ; if there 

 is a precipitate it is collected on a filter, and the sulphate of 

 baryta obtained furnishes the amount of sulphur present. Next 

 pass a stream of sulphureted hydrogen through the filtrate to 

 complete saturation, previously adding a drop or two of sul- 

 phuric acid; much sulphur will be deposited and a very minute 

 quantity of copper (not traceable by the color of the precipitate, 

 but only recognized by the most delicate tests after the sulphur 

 of the collected precipitate is burnt away); the solution thrown 

 on a filter leaves the precipitated sulphur, the little trace of 

 copper, and all the excess of the baryta that had been added, 

 if the excess had been slight. The filter is then ignited in a 

 porcelain crucible ; the residue treated with a few drops of nitric 

 and sulphuric acids, which suffices to dissolve the copper, and 

 when evaporated to dryness leaves the copper in the form of 

 sulphate, slightly acid, as there is no necessity of heating so 

 high as to drive off the very last trace of sulphuric acid. The 

 presence of the trace of copper is easily shown by adding a 

 drop or two of water to dissolve the sulphate, and with the 

 end of a glass rod placing a little of the solution on a clean and 

 bright surface of iron, as the blade of a knife, for instance. In 

 no examination of a meteoric iron have I failed to detect copper 

 by this means. 



When more iron is used, and there is consequently more 

 copper, it can be separated and weighed. Tin and lead will 

 also be found in the precipitate if they be present; but I have 

 never detected either, except lead in the case of the Tarapaca 



