PHYSIOGRAPHY. . 



would in every respect be foreign to the purposes of a 

 collective description ; but that they are intended mere- 

 ly for producing a general survey of every thing relative 

 to those compositions contained within the limits of the 

 species. 



The same applies also to amorphous compositions, or, as 

 they are more commonly called, to the massive varieties. 

 As to these, the most important properties to be mentioned 

 here will be, the shape of the component particles, their 

 size, mode of aggregation and fracture ; for, according to 

 these properties, the species of rhombohedral Lime-haloide 

 has been divided into foliated, fibrous, and compact Lime- 

 stone, together with their farther subdivisions ; and like- 

 wise the oryctognostic species of Slate-spar, Anthracolite 

 Chalk, Rock milk, and others, have been formed under the 

 same influence of composition, as will appear more evident- 

 ly in the Observations annexed to the description of the pre- 

 sent species. Thus we are capable of expressing in a few 

 words, much that has been described with great prolixity 

 in mineralogical works ; while we enjoy the advantage of 

 arriving at an idea of the subject, correct and general, and 

 conformable to nature. 



Also the pseudomorphoses need nothing more than to be 

 mentioned. Even though their appearance be regular, 

 they so little refer to the internal quality of the species, 

 that their knowledge does not add to our general know- 

 ledge of the species. 



The arrangement of all the other collective descriptions 

 is the same as that explained in the preceding example, 

 taken from rhombohedral Lime-haloide. If other pro- 

 perties should happen to occur than those mentioned here, 

 these properties will likewise be inserted in a proper or. 

 der, provided they contribute to our natural-historical 

 knowledge of the species in question ; whereas others men- 

 tioned in rhombohedral Lime-haloide, if they be wanting, 

 will be passed over in silence. In general, some one or 

 other of the natural-historical properties of the species may 

 be rendered more prominent, the more it contributes to a 



