4 Davison — Platinum and Iridium in Meteoric Iron. 



Art. 11.— Platinum and Iridium in Meteoric Iron; by 

 John M. Davison. 



[Read before the Rochester Academy of Science on October 11, 1898.] 



Some time ago a color reaction, given by potassium iodide 

 with a residue from a solution of Coahuila meteoric iron, led 

 me to suspect the presence of platinum. To test the matter, 

 three attempts were made to separate this element from 

 meteoric iron; the first with 108-6 grams of the Coahuila 

 iron ; the second with 500 grams of the same iron ; the 

 third with 464 grams of the Toluca iron. The hydro- 

 chloric acid solution of these irons left a fine black sediment 

 consisting mainly of minute, tetragonal, prisms of rhabdite ; 

 minute, black, irregular crystals, which may also be rhabdite ; 

 carbon, and a little stony matter. 



From this sediment platinum was obtained in each analysis. 

 There was got from the 608*6 gms. of Coahuila iron 0*014 gms. 

 of metallic platinum, and 0*0015 gms. of a black powder, 

 insoluble in nitro-hydrochloric acid, but, after fusion with zinc, 

 dissolving in that acid and giving with ammonium chloride a 

 dark-red crystalline precipitate, which is probably ammonium 

 iridi-chloride. 



From the 464 gms. of Toluca iron a few crystals of potassium 

 platinichloride were obtained. These show a reddish color, 

 and probably contain iridium. The hydrochloric acid treat- 

 ment of 500 gms. of Coahuila iron left 9*386 gms. of residue: 

 that of the 464 gms. of Toluca iron left 0*944 gms. of residue, 

 which contained more stony matter than did that from the 

 Coahuila. This stony matter was much decomposed by the 

 acid. 



Careful search was made for microscopic diamonds. None 

 were found in either meteorite. The few transparent grains, 

 left with the carbon after all soluble matter had been removed, 

 were decomposed by hydrofluoric acid. 



From these analyses all platinum utensils were, of course, 

 carefully excluded, the reagents tested, and all precautions 

 taken against accidental contamination. 



