$$$ Introduction to the Study of Mineralogy. 



ever, that the learned have begun to submit the assemblage 

 of inorganic bodies to methodical arrangements, and that 

 the term mineral kingdom has been adapted. Among the 

 various systems which have successively appeared, some 

 of them, such as those of Linnaeus, Wallerius, Daubenton, 

 &c, employ in the determination of the species, genera, 

 orders and classes, certain characters which are, as it were, 

 presented to the naked eye; such as those which are derived 

 from the form, texture, and transparency of the colours ; 

 or certain properties easily verified, such as those of emitting 

 light with steel, effervescence with nitric acid, he. Other 

 systems, subjected to a more scientific progress, as traced 

 by Cronstadt, and followed by Bergman, Born, Kirwan, 

 &c, present the series of minerals classified according to 

 their analyses ; so that, the species being determined by the 

 identity of the component principles, the genera are formed of 

 species which have a common principle. The same method 

 also serves in certain cases to connect together several genera 

 in one and the same order: thus the neutral salts may be sub- 

 divided into alkaline salts, earthy salts, and metallic salts, 

 according to the kind of acid united to an alkali, an earth, 

 or a metal. But when analysis failed in enabling mineralogists 

 to form orders, its place was supplied by some chemical 

 property common to all the genera of which each order w r as 

 the assemblage ; and with respect to the classes, they were 

 in the same way characterized after the manner in which 

 the substances which composed them were modified in the 

 various operations which spring from chemistry. 



It must not be thought, however, that there was a line 

 of separation clearly traced betwen the two modes of me- 

 thodical distribution which we have mentioned. Chemists, 

 after having determined the series of the classes, orders, ge- 

 nera, and species, by the help of chemical properties, or of 

 the results of analysis, could not descend to the varieties, 

 except by employing external characters in order to distin- 

 guish them from each other. Now, in a complete method, 

 we are the less entitled to dwell upon the species, as they 

 4re frequently ramified into several subdivisions, the diffe- 

 rences of which; much more striking than those light and 



fugitive 



