. 255:* PHYSIOGRAPHY* 3 



whole species, nor can their description be substituted in- 

 stead of the description of the species. The description of 

 all the varieties of a species does not produce a clear idea 

 or representation of the species itself; because the species 

 is not a single body, but the assemblage of all the homoge- 

 neous individuals or varieties (. 220.). Thence we infer 

 that the species in Mineralogy is not properly an object for 

 a description ; and the latter will not therefore allow of 

 the same use in the Mineral Kingdom, to which it is 

 adapted in the Animal and Vegetable Kingdoms. 



In the Mineral Kingdom, only individuals (or composi- 

 tions (. 23.) of individuals), admit of being described, and 

 this is effected by indicating all their natural-historical pro- 

 perties. In enumerating these, it is useful to keep to a cer- 

 tain determined, though in itself arbitrary order of succes- 

 sion, which, for the sake of perspicuity, should remain unal- 

 tered, if it has once been fixed upon. All prolixity should 

 be carefully avoided, every superfluous word, every not per- 

 fectly determined expression, in short, every thing foreign 

 to the purpose, should be rejected ; and such terms em- 

 ployed as are explained in the Terminology. Many obser- 

 vations apply also to the present subject, which have been 

 made to the same purpose in the introduction to the Cha- 

 racteristic. 



Descriptions are required, whenever there occur new 

 varieties of a species, the latter being either already known, 

 or entirely new ; they are also useful in such varieties as are 

 distinguished by a particular application, or any remarkable 

 property, or such as have been provided with particular 

 names in the arts of life. In the latter, it is only necessary 

 to indicate those properties, by which the variety in ques- 

 tion differs from other varieties of the same species. It is 

 very useful to give an accurate description of such indivi- 

 duals, as are subjected to a chemical analysis. 



. 255. GENERAL DESCRIPTION OF THE SPECIES. 



In order to represent the natural-historical spc- 



