THE RARE EARTHS. MAGEE. Ixiii 



The full list of these earth elements includes Ce., Zr., Th., La., Sc., 

 Yt. and Yb., which are looked upon by chemists as actually elemental, 

 and Pd., Nd., Sm., Ho., Er., Ter., Th., De., Dp., Ph., and even others 

 which appear to differ from each other as oxides and may, some of them 

 at least, be elemental, but are probably in most cases mixtures of two or 

 more elements. They are not, however, known in the elemental con- 

 dition but only in the form of oxides and salts. Some few have been 

 reduced to the metallic condition yielding then grayish-white metals, but 

 in such small quantities, and with such doubts regarding their purity, 

 that slight advantages have been derived from the reduction. 



Before considering the properties of these substances and discussing 

 their importance in the periodic system, it will be well to look into their 

 history. They were first brought to the knowledge of the chemical 

 world during that period of remarkable activity at the close of the 18th 

 and beginning of the 19th centuries. Probably the first time that any 

 mineral containing these oxides in any considerable quantity was noticed 

 was in 1751, when Cronstedt obtained from an iron mine in Sweden a 

 sample of the mineral now known to mineralogists as Cerite, a silicate of 

 Ce., La. and Di., containing as impurities or accessories, however one 

 chooses to consider them, small quantities of other rare oxides, together 

 with iron, alumina, lime and traces of Mn., and even other minerals. 

 This mineral was first analysed by D'Elhuyar in the laboratory of the 

 noted chemist Bergmann, and stated to be a silicate of Fe. and Ca. It 

 may seem remarkable that, even in those early days of chemistry thia 

 was in 1784 such an error as the mistaking of the trivalent oxides for 

 the very common substance lime should occur, but if the experience of 

 such a noted analytic chemist as Plattner, so late as 1846, be considered, 

 all wonder ceases. This chemist analysed several times the mineral 

 Pollux froiu Elba and, despite all his care, and he \vas renowned as an 

 analyst, he could only get his results to foot up to 92.75 per cent., nor 

 could any one explain the matter until Bunsen recognized a new metal, 

 Caesium, in the water of the Durkheirn salt well-* and proved it to be 

 of the alkali group thus closely resembling Xa. and K Plattner had 

 been reckoning Cs. with an atomic weight of 132 as K. with an atomic 

 weight of 39, and neither he nor his contemporaries seemed capable of 

 proposing the very simple explanation that there must be present a new 

 element. This experience of Piattner's and its explanation probably 

 saved Winkler from a similar error in 1886 and gave him the credit of 

 the discovery of a new element. Repeatedly analysing Argryodite, as 



