PHYSIOGRAPHY. 255 



much that has been described with great prolixity ; while we enjoy 

 the advantage of arriving at an idea of the subject, correct and gen- 

 eral, and conformable to nature. 



The pseudomorphoses need nothing more than to be mentioned. 

 If other properties should happen to occur beside those above allu- 

 ded to, they will be inserted in a proper order, provided they con- 

 tribute to our knowledge of the natural properties of the species to 

 which they belong; whereas, if any of the foregoing are wanting 

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

 of the natural properties may be rendered more prominent, the more 

 it contributes to a clear and distinct image of the species. 



The collective descriptions of the species form one of the most im- 

 portant subjects of the Natural History of the mineral kingdom. 

 Although they represent the mineral species by themselves, not 

 regarding their resemblance to others, yet they effect this in the 

 minutest detail, and to the greatest possible completeness, and hence 

 they contain all the natural historical information, properly so call- 

 ed, relative to mineral productions. 



. 127. COLLECTIVE DESCRIPTIONS INDEPENDENT OF 

 ALL SYSTEMS. 



The collective descriptions do not depend upon the sys- 

 tems ; but are applicable in every system. 



The collective description represents the natural historical species 

 developed in the minutest detail. This species is the basis of every 

 method, or in fact of every science, which refers to the productions 

 of the mineral kingdom : it is the object, not the product of classifi- 

 cation. It may be applied in a natural or artificial system, whether 

 drawn up in conformity with the principles of Natural History, or 

 to those of any science : nor is it less applicable in an alphabetical 

 arrangement, since descriptions are consulted very much after the 

 manner of a dictionary of words. 



. 128. ADDITIONAL INFORMATION APPENDED TO THE 

 COLLECTIVE DESCRIPTIONS IN THE SECOND PART OF 

 THIS TREATISE. 



The general descriptions limited as above (. 126), ne- 

 cessarily exclude a variety of important information (most- 



