28 HEYL— PLATINUM IN NORTH CAROLINA. [February 7, 



crushed and then ground to fine powder in rolls, with the idea of 

 finely dividing the rock without reducing the size of the metallic 

 particles, if any such were present. The ground mixture assayed 

 0.4 ounces per ton Pt, which would mean 60 milligrammes of metal 

 in the lot. Concentration was effeoted by very gentle washing in 

 the following manner: the sand was placed in a large jar, and a 

 small stream of water introduced by a tube reaching to the bottom 

 of the jar, and the water allowed to overflow until it ran perfectly 

 clear. The residue, which amounted to about one third of the origi- 

 nal amount, was dried and put thiough the rolls again, afterwards 

 being washed in the same manner as before. After several repeti- 

 tions of this process there remained a few grams of material, which 

 was pulverized by hand in an agate mortar filled with water, a little 

 at a time. The very fine material thus resulting was panned off 

 from time to time and there remained finally a surprisingly large 

 amount of flattened metallic particles. On digestion wuth hydro- 

 chloric acid the greater part of these dissolved with the familiar 

 odor which showed them to be particles of steel derived from the 

 grinding machinery. There remained 13.8 mg. of bright metallic 

 particles. These were not attacked by dilute nitric acid. On heat- 

 ing to redness on the lid of a porcelain crucible many of the particles 

 preserved their luster unchanged, and some of them turned a steel 

 blue without loss of luster. A few particles showed the change of 

 color over a part of their surface, suggesting palladium. (Samples.) 

 The quantity of material was rather small for an analysis, but 

 the attempt was made. The particles were fused with zinc for an 

 hour and the button dissolved in hydrochloric acid. The fine black 

 residue was treated with aqua regia diluted with four volumes of 

 water for a long time, and there remained a small black residue 

 which was probably iridium. It weighed 0.4 mg., and was unaltered 

 in appearance by ignition. The solution was evaporated to dryness 

 and taken up with 60 per cent, alcohol and solid NH^Cl. A small 

 brick-red precipitate remained. On ignition the mixed Pt and Ir 

 sponge weighed J.-j mg. The alcoholic filtrate was yellowish, and 

 gave a reaction for iron. This is significant in connection with the 

 fact that the particles had withstood both hydrochloric and dilute 



