183.5.] Scientific Intelligence. 317 



V. — Massy Iridium, by Gustav Rose. 

 In the ix. vol. s. 1. and s. 96, of Schweigger's Jahrbuch fur 

 Chcmie and Phijsik, Breithaupt describes grains which were dis- 

 tinguished in the Uralian Platinum, and possess the highest specific 

 gravity of any known substance. 



The grains are round and full of small cavities, and sometimes 

 assume the appearance of crystallization. Breithaupt considers them 

 fragments of octahedrons. Their cleavages are in three directions. 



The grains possess a strong metallic lustre ; externally their colour 

 is silvery white, which passes into yellow ; internally they are silver 

 white, passing into platinum gray. 



Their hardness is between that of felspar and glassy. They po- 

 lish the best file, and are consequently harder than all known metals 

 and metallic compounds. They are but slightly ductile. The 

 specific gravity of several grains which weighed together 01035 

 drachms, Breithaupt found to be 23*646. The density of two single 

 grains which weighed 0*03875 and 0-0404 drachms (about 0-14 

 and 0*136 grms or 2*167 and 2*098 E. grains,) he found to be 

 21-527 and 22*494. 



Breithaupt and Lampadius found by examination that these grains 

 consisted of iridium, with very little osmium, from which circum- 

 stance the new mineral was termed massy iridium. 



Last summer Professor Schiiler came from Freiberg to Berlin, 

 and brought with him a grain which Breithaupt stated to agree with 

 those described. Schiiler allowed Gustav Rose to take the specific 

 gravity. He found it 21*85, the temperature of the water being 

 12' R. (590 Y.); its absolute weight was 0284 grms. (4.082 grs.) 

 It resembled in appearance another grain which Rose had found 

 among a portion of osmium-iridium from Newiansk in Ural. He 

 took the specific gravity of this also. Its absolute weight was 0*2622 

 grms; its specific gravity 22-800 at 59'' F. 



The grain was originally larger, but Rose had broken oflP a portion 

 to ascertain whether it possessed the cleavage of osmium-iridium, for 

 which mineral he had mistaken it previous to the arrival of Professor 

 Schiiler. 



The fragment when examined before the blowpipe, as with the 

 common osmium-iridium, yielded no smell of osmium and underwent 

 no change. 



These grains agreed in colour with a crystal which Rose brought 

 from Nischne Tagilsk, resembling what he had described as lead- 

 gray plates of osmium-indium. It was a combination of the 

 hexahedron with the octahedron, the faces of the latter predomi- 

 nating ; the faces of the hexahedron were about one line broad. 

 Rose did not examine it further until Breithaupt, when at Berlin, 

 saw it, and from its white colour suggested that it might be the same 

 as his massy iridium. The determination of its specific gravity con- 

 firmed this suspicion. Its density was 22*65 at 53|o ; its absolute 

 weight -188 grms (2*9 grs.) 



Rose sent a portion to Berzelius for analysis. It was examined 



