290 Reflections on some Mineralogkal Systems, 



algebraic language, for to find the value of x, we must 

 commence with knowing it. 



AVERNERIAN DIVISION OF THE EXTERNAL CHARACTERS. 



M. Werner has divided the external characters into ge- 

 neric characters, specific characters, and characters of va- 

 rieties which influence the systematical distribution of mi- 

 nerals under analogous denominations. The colour, lustre, 

 and specific gravity undergo subdivisions. White, gray, 

 black, blue, green, yellow and brown, are species among 

 the colours. The shades of these characters form subdivi- 

 sions, and they are pronounced in adding an epithet to the 

 word which designates the specific character. Thus, cela- 

 don- or sea-green is a variety of green ; gosling- {serin) green 

 is another,- sky-blue is a variety of blue, as sulphur-yellow 

 is one of yellow. These distinctions cannot be mistaken 

 as soon as we understand to pronounce the attributes of the 

 specific colour according to the rules. But the difference 

 between celadon-green and gosling-green is really greater 

 than between sky-blue and celadon-green, and the same 

 between gosling-green and sulphur-yellow: that is to say, 

 the varieties of the same species differ more from each other 

 than two species differ. This mode of distribution may- 

 suffice for the nomenclature, but by no means for the thing; 

 it satisfies the ear, because the ear does not judge of colours. 



The division of external characters into specific and ge- 

 neric characters, and characters of variety, places us in a 

 new difficulty ; for we here see a third principle of classifica- 

 tion relative to minerals. We had the number of different 

 characters, and the value of each character; now we have 

 the intensity of these same characters. It is also impossible 

 to see clearly how we ought to form species and varieties 

 in minerals : if it is by the number solely, we exclude the 

 importance of characters, and the shades are all of the same 

 value ; if we concede any thing to the importance, we must 

 modify the rules respecting the number; and if the character 

 of variety be sufficient to establish the mineralogical variety, 

 as but one is wanting, What shall we do when it is a specific 

 character which differs? How many characters of variety 

 are equivalent to a specific character ? How many to a gene- 

 ric ? In all these', too, we must carefully avoid taking the least 

 possible difference of characters to establish the mineralo- 

 gical subdivision, which is not itself the smallest. 



Unity of principle in a system of classification is that 

 which tends most to give it precision. If we feel ourselves 

 obliged to admit several principles, it loses this advantage, 



unless 



