^^6 Professor Necker o-n Mineralogy considered 



character to distinguish the salts from other minerals, which re- 

 quire for their solution a much greater quantity of water. 



For the same reason, although it is well known that metals, 

 when divided into extremely thin laminae, transmit light, yet, as 

 they never occur in nature in such a state as to exhibit this pro- 

 perty, to which they can be brought only by artificial and diffi- 

 cult contrivances ; and, as their smaller natural fragments exhi- 

 bit on the contrary complete opacity when compared with frag- 

 ments of equal size of other minerals, we may term them opaque 

 without being taxed with inaccuracy. 



In like manner, when we have previously mentioned the kind 

 of fire, blowpipe, and gas employed to effect the combustion, 

 and when the size of the fragment of mineral tried has been ap- 

 proximately indicated, we may use the character of fusibility or 

 infusibility as perfectly correct, notwithstanding that, in circum- 

 stances different from those mentioned, the case would have 

 proved different. 



Sect. II. — Of the relative value or importance of 

 :^/. characters. 



-§ 29. The subject we are about to bring under consideration 

 presupposes in the reader an acquaintance with what is meant 

 in natural history by the expressions artificial methods or sys- 

 tems, and by the natural metliod of classification. Should he be 

 unacquainted with the views on this subject, we would refer him 

 to Cuvier's Regne Animal, but more especially to the deep and 

 elaborate disquisition on this subject contained in De Candolle's 

 masterly work, the Theorie Elementaire de la Botamque. 



It will be sufficient for our present purpose, to remind the 

 reader that an artificial method, not having it in view to assem- 

 ble the beings which it considers, according to their more im- 

 portant and more numerous analogies, does not make use of the 

 whole of the properties or organs as characters, and does not 

 attend to the natural subordination of those characters : that 

 a system is founded on the consideration of a single set of or- 

 gans or of characters, so that it is always entirely artificial, being 

 generally constructed in order to facilitate the discovery of the 

 name of the being. The natural method is founded on a tho- 

 rough knowledge of the being in all its real and effective rela- 

 tions to the other beings. It arranges all the individuals toge- 



