188 Dh. Andebson on the Recent Progress of our 



effected in a manner similar to that of the Cerium and Lautanium. 

 Owing to the rarity of the minerals containing these substances, very 

 little is yet known regarding their properties ; indeed, the metals 

 themselves have not yet been separated, and even their oxides have 

 been most imperfectly examined. 



Shortly afterwards, Svanberg was induced to examine Zii-conia, being 

 led to anticipate the possibility of different substances being found in 

 the zircon of different localities, from the conspicuous differences, and 

 their specific gravity, which varies at between 4*0 and 4w, and he believes 

 that the Zirconia of BerzeUus contains three different substances. To 

 one of these, which gives a readily crystallizable sulphate, he has assigned 

 the name of Noria, and to its metal Xorium. It is found most abun- 

 dantly in the Norwegian Zircon. Eudialyte, according to Svanberg, 

 also contains two new earths, one resembling Yttria, the other yellow. 

 It is right, however, to mention that considerable doubt still 

 attaches to these substances, and Berlin has failed to confirm Svanberg's 

 results. 



In the year 1801, Hattchett discovered in an American mineral a 

 metal which he called Columbium, and in 1802 Ekeberg found in a 

 Swedish mineral another which he namedTantalum ; and in 1 809, Wollas- 

 ton declared these substances to be identical. Rose was led to re-examine 

 this subject in 1846, by observing the great difference in specific gravity 

 of the Tautalites of different kinds, the black variety from Bodenmais 

 having a specific gravity of 6 '39, while the reddish-brown fi-om the 

 same locality is 5*69, and the American 5 "70, and he found them to 

 contain a metal distinct from Skeberg's Tantalum, to which he gave the 

 name of Niobium. He also at the same time stated that they contained 

 a third metal which he called Pelopium, but subsequent experiments 

 satisfied him that it was not a distinct substance. The metals, Tanta- 

 lum and Niobium, ai-e scarcely known,but they both form acid compovmds 

 with oxygen, which are distinguished by very marked differences. One 

 of the most curious is the effect of heat in modifying their specific 

 gravity, Tantalic acid in its ordinary state having a specific gravity of 

 7*284, which is increased by a strong heat to 7 99, while Niobic acid 

 is reduced by heat from 5'12 to 460. 



A mineral, very similar in properties to Yttrotantalite, has been found 

 in the Ilmen mountains in Siberia, to which the name of Yttroilmenite 

 has been given. Herman, who has examined this mineral, beUeves it to 

 contain a metal which he calls Ilmeniura, but Rose considers this to be 

 merely niobium contaminated with a little tungstic acid. 



The residues obtained during the purification of platinum have also 

 vielded a new metal, which its discoverer, Glaus, calls Ruthenium . It is 



