1018 



SCIENCE. 



[N. S. Vol. XI. No 287 



It was ia 1803 that Collet-Descotils had 

 read a paper before the Institute of France 

 on the cause of the different colors which 

 affect certain salts of platinum. The resi- 

 due from the solution of platinum ores in 

 aqua regia and which was thought to be 

 graphite, was still slightly soluble in aqua 

 regia and gave a reddish tint to the potas- 

 sium chlorplatinate made from it. The 

 metal derived from this red salt was found 

 to be only partially soluble in aqua regia 

 and hence beyond question Descotils had in 

 hand on several occasions a fairly pure irid- 

 ium, containing, however, in addition to 

 platinum perhaps traces of rhodium. He 

 was convinced that he had here a new metal 

 but he did not investigate its properties.* 



The same day that Descotils spoke before 

 the Institute, a second paper on the same 

 subject was presented by Fourcroy and 

 A'^auquelin. After extracting the platinum 

 fi<jm the ore by aqua regia, they fused the 

 residue with potash and then treated it 

 with acid. These chemists noticed that 

 the potash was colored orange-yellow, but 

 ascribed it to the presence of chromium. 

 They thus missed the discovery of ruthen- 

 ium, which was to be separated several 

 decades later by Claus. They noticed also 

 on one occasion that the black powder 

 which consisted of iridium and allied 

 metals, was apparently volatile, not recog- 

 nizing osmium, the cause of the phenome- 

 non. In their second memoir they had 

 iridium fairly pure, and they too noticed 

 the rose color of the double salt, but did 

 not investigate the cause, which is the pres- 

 ence of rhodium. 



would help them to anticipate him in the matter of 

 rhodium, -while if he kept silence, ?ome of them 

 could not fail to discover palladium. 



*0f this Descotils writes {Ann. de Ckim. 48, 165 

 1803) : On peut diSja conclure que la coloration en 

 louge des sels de platine est due a I'oxigenation 

 d'une substance qui differe du platine, et qui pre- 

 sente, lorsqu'elle est a I'^tat metallique, une grande 

 resistance a I'action des acides. 



It was reserved for Tennant the follow- 

 ing year to describe clearly the separation 

 of iridium and osmium from the platinum 

 residues, and to name the one from the 

 many different colors through which its 

 chlorids pass, and the other from the intol- 

 erable odor of its tetroxid OsO^. 



This osmium contained ruthenium but 

 this was overlooked by Tennant, as it had 

 been by Fourcroy and Vauquelin. A few 

 years later Vauquelin* notes that osmium 

 solutions give a beautiful blue color when 

 reduced by zinc, this being a characteristic 

 reaction, not of osmium but of ruthenium. 

 At a still later date Berzelius noticed the 

 orange color of the fusion of ruthenium 

 with potash and saltpeter, but he attributed 

 it to iridium. 



It was in 1828 that the next effort was 

 made to add to the number of the platinum 

 metals. Professor Osann, of the University 

 of Dorpat, announcedf the discovery of a 

 new metal in the platinum residues. He 

 obtained long reddish prisms, with high 

 luster, which were easily volatile and which 

 Berzelius pronounced to be new. He had 

 only 0.3 gram, and never obtained any 

 more. The metal in these crystals he 

 named ruthenium. They maj^ have been an 

 impure mixture of the tetroxids of ruthen- 

 ium and osmium. In the next volume of 

 the AnnalenJ he transfers the name ruthen- 

 ium to another new metal with a golden 

 luster, and at the same time he mentions 

 two other metals, liluran, named from pi 

 (atina) and ur (al), which is not further 

 described, and polin {-oXioi, gray), a gray 

 metal of whose independent existence he 

 seems to have some doubt. Polin was im- 

 pure iridium with perhaps some ruthenium; 

 pluran was quite possibly a mixture con- 

 tainingsome ruthenium; thefollowing year§ 



"Ann. de Clum., 89, 241 (1814). 

 fAnn. derplujs. (Pogg.), 13, 287 (1828). 

 tAnn. derpliys. (Pogg.), 14, 340 (1828).] 

 I Ibid., 15, 158 (1829). 



