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Report on the Recent Progress of our Knowledge of the Chemical Elements. 



Bj' De. Thomas Andeeson. 

 He commenced by observing tbat the progress of a science is rarely 

 uniform in all its departments, but that now one portion and then an- 

 other claims the special attention of its cultivators, and advances with 

 more than ordinary rapidity. The truth of this statement is well 

 illustrated by our knowledge of the chemical elements, a subject which 

 within the last few years has been studied with reraai'kable activity, and 

 has given a rich harvest of new and unexpected results. After the 

 brilliant discoveries which marked the end of the last and beginning of 

 the present century, among which it is scarcely necessary to refer to the 

 isolation of the alkahne metals by Davy, and the discovery in France 

 of iodine and bromine, a long period elapsed during which scarcely any- 

 thing was added to our knowledge of the elements, and in fact the 

 dearth of novelty was so great that the behef gained ground that this 

 department of chemistry had been completely exhausted. The fallacy 

 of this idea was demonstrated, and a new epoch of progress in this branch 

 of science commenced by Mosander's discovery of Lantanium in the 

 year 1839, a discovery of peculiar interest, because it indicated a method 

 of inquiry by which great additions to the number of the elements have 

 since been made. 



In the year 1803, Berzelius and Hisinger discovered a metal to which 

 they gave the name of Cerium, and which had remained without further 

 examination until it was again investigated by Mosander, who found it 

 to be really a mixture, as he at first believed, of two, but as he subse- 

 quently showed, in 1841, of three different metals. For one of these he 

 retained the name of Cerium, and the other two he called Lantanium and 

 Didymium. These substances had escaped the notice of Berzelius and 

 Hisinger, because they operated on a very small scale, and as the 

 metals, though unequivocally different, are very similar in many of 

 their properties, it is easy to understand how they came to be over- 

 looked. Of the metals themselves very little is yet known, but the 

 oxides are readily distinguishable ; thus, for instance, the oxide of cerium 

 is yellow or buff, that of lantanium white, and that of didymium 

 dark brown. Their separation is very difficult and depends mainly on 

 the difference of their afiinity for acids. The result of his investiga- 

 tion led Mosander in 1843 to examine the metal Yttrium, which was 

 discovered by Gadolin in 1 794, and it also proved to contain three dif- 

 ferent substances, which arc now known by the names of Yttrium, 

 Erbium, and Terbium; all derived from Ytterby, the name of the place 

 where the mineral containing them is chiefly found. The separation is 



