200 HISTORY OF CHEMISTRY. 



ference of metallic and non-metallic, is another 

 element. Thus Thenard, in the first place, speaks 

 of Oxygen ; in the next place, of the Non-metallic 

 Combustibles, as Hydrogen, Carbon, Sulphur, Chlo- 

 rine; and in the next place, of Metals. But the 

 Metals are again divided into six Sections, with re- 

 ference, principally, to their facility of combination 

 with oxygen. Thus, the First Section is the Metals 

 of the Earths ; the Second, the Metals of the Alka- 

 lies ; the Third, the Easily Oxidable Metals, as Iron ; 

 the Fourth, Metals Less Oxidable, as Copper and 

 Lead ; the Fifth Section contains only Mercury and 

 Osmium; and the Sixth, what were at an earlier 

 period termed the Noble Metals, Gold, Silver, Pla- 

 tinum, and others. 



How such principles are to be applied, so as to 

 produce a definite and consistent arrangement, will 

 be explained in speaking of the philosophy of the 

 Classificatory Sciences; but there are one or two 

 peculiarities in the classes of bodies thus recognized 

 by modern chemistry, which it may be useful to 

 notice. 



1. The distinction of Metallic and Non-metallic 

 is still employed, as of fundamental importance. 

 The discovery of new metals is so much connected 

 with the inquiries concerning chemical elements, 

 that we may notice the general progress of such 

 discoveries. Gold, Silver, Iron, Copper, Quick- 

 silver, Lead, Tin, were known from the earliest 

 antiquity. In the beginning of the sixteenth century, 



