as a Branch of Natural History, ^c. 



scriptive one. It being our object to place it on a true basis, 

 we must study the nature of the characters employed in zoolo- 

 gy and botany, as far as relates to their relations to the animal 

 or plants described, and from that study derive rules which we 

 shall afterwards apply to mineral individuals. We have made 

 the required study, and,' by a comparison of what has been 

 done in zoology and botany with what has- been effected in mi- 

 neralogy, we have been led to establish the following rules des- 

 tined to guide us in the choice of proper characters on which 

 we are to fix the divisions of the classification from the highest 

 down to the lowest. 



§ 25. In the first place, the character must belong to the in- 

 dividual itself, and not to one only of its constituent parts or 

 elements. This rule, therefore, excludes entirely the use, so 

 often made, in the highest divisions especially, of certain ab- 

 stract characters belonging only to one or to another of the ele- 

 ments of the chemical combination. Such, for instance, as the 

 character of being autopside or heteropside, electro-positive or 

 electro-negative, which belongs to one of the simple or element- 

 ary metals entering into the composition of a mineral, and not 

 to the compound substance of the mineral, nor to the mineral 

 itself, which is neither autopside nor heteropside, neither electro- 

 positive nor electro-negative. For the same reason we ought to 

 avoid giving to a collection of minerals, in the composition of 

 which a malleable metal forms a constituent part, the character 

 of malleability as the distinctive character of the family, because 

 most of the individuals being compounds of one of these metals 

 with combustibles, with oxygen, with acids, &c. are not them- 

 selves malleable. But if a distinction was required only between 

 metals in their native state, then the character of malleability 

 would be a very proper one. 



_ § 26. Secondly, the characters must be immediately recog- 

 nised in the individual, or at least by such means that the indi- 

 vidual, or a physical part of it, representing exactly the whole, 

 being always present to the eye of the observer, there should be 

 no doubt that the property manifested does belong to the indi- 

 vidual, and belongs to it alone. In this respect all the external 

 characters, as well as the physical ones, and many of the chemi- 

 cal properties, inasmuch as they are recognised before the body 



