FRANKLIN COUNTY (KY.) METEORIC IRON. 355 



and by it I have never failed to detect and estimate cobalt in 

 every meteoric iron that has come under my examination. 



In examining for phosphorus the following method is adopted: 

 To three or more grammes of the iron, in a porcelain capsule, 

 add nitric acid diluted with water; then invert a funnel over 

 the mixture to protect from loss during the action, evaporate 

 to dryness over a water-bath, and then on a sand-bath to a 

 temperature of 500° to 600°; the iron is thus converted into an 

 oxide with little or no nitric acid remaining, and the phosphorus 

 is transformed into phosphoric acid that is now combined with 

 oxide of iron. The residue is detached as thoroughly as possible 

 from the capsule and mixed with twice its weight of carbonate 

 of soda, or, better still, with a mixture of carbonates of soda 

 and potash ; a little carbonate of soda added to the capsule and 

 rubbed with a pestle detaches the last portion of oxide of iron, 

 or rather leaves so small an amount as to make no error in the 

 future steps of an analysis where the original quantity of phos- 

 phorus is so small. 



The mixture of oxide of iron and phosphate is now to be 

 heated in a platinum crucible to the point of fusion of the 

 carbonates for about twenty minutes; then heat the mass with 

 water, when the excess of carbonates will be dissolved, and 

 what phosphate may have been formed. The phosphates 

 will represent all the phosphorus in the iron. N"ow neutralize 

 the carbonate with hydrochloric acid, and estimate the phos- 

 phorus in the ordinary way by a magnesia salt. 



With regard to the detection of chromium and other special 

 constituents of some meteoric irons, especially those containing 

 some siliceous minerals intimately mixed in the iron, it is not 

 the province of this paper to discuss. 



3. Lead in Meteoric Irons. 



The only instance of the finding of lead in meteoric irons is 

 that of the Tarapaca iron, found in 1840, in Chili, which was 

 examined by Mr. Greg; the metallic lead was detected by him 

 in small masses of varied dimensions. 



I have examined several specimens cut from the original 

 mass of iron, two of which are in my possession, and my con- 

 viction is that the metallic lead was altogether foreign to the 

 iron when it originally fell, and has been doubtless derived 



