TRANSITION TO CLASSIFICATORY SCIENCE. 201 



mine-directors, like George Agricola, had advanced 

 so far in practical metallurgy, that they had dis- 

 covered the means of extracting three additional 

 metals, Zinc, Bismuth, Antimony. After this, there 

 was no new metal discovered for a century, and 

 then such discoveries were made by the theoretical 

 chemists, a race of men who had not existed before 

 Beccher and Stahl. Thus Arsenic and Cobalt were 

 made known by Brandt, in the middle of the eigh- 

 teenth century, and we have a long list of similar 

 discoveries belonging to the same period; Nickel, 

 Manganese, and Tungsten, which were detected by 

 Cronstedt, Gahn and Scheele, and Delhuyart, re- 

 spectively ; metals of a very different kind, Tellu- 

 rium and Molybdenum, which were brought to light 

 by Miiller, Scheele, Bergman, and Hielm; Plati- 

 num, which was known as early as 1741, but with 

 the ore of which, in 1802 and 1803, the English 

 chemists, Wollaston and Tennant, found that no less 

 than four other new metals (Palladium, Rhodium, 

 Iridium, and Osmium) were associated. Finally, 

 (omitting some other new metals,) we have another 

 period of discovery, opened in 1807, by Davy's dis- 

 covery of Potassium, and including the resolution 

 of all, or almost all, the alkalies and earths into 

 metallic bases (K). 



2. Attempts have been made to indicate the 

 classification of chemical substances by some pecu- 

 liarity in the Name ; and the Metals, for example, 

 have been designated generally by names in urn, 



