. &27. THEORY OF THE SYSTEM. 337 



Mineral Kingdom. These are the ideas of the Order 

 and of the Class. 



. 227. ORDER. 



The Order is an assemblage of similar genera. 



The order is in respect to the genera, what the genus is 

 in respect to the species. The idea of the order is there- 

 fore perfectly evident from the preceding inquiries ; and the 

 only object that requires some consideration in the present 

 place, is to shew its application to the Mineral Kingdom. 



The genus Iron-pyrites, in the peculiar place it occupies 

 in the general series of genera, is surrounded by several 

 other genera, which exhibit so high a degree of resemblance 

 to each other, that they seem to have been formed after a 

 common type or original. These are, the genera Nickel- 

 pyrites, Cobalt-pyrites, Arsenical-pyrites, and Copper-py- 

 rites. There is not another genus to be found in the whole 

 Mineral Kingdom, as hitherto known, which could be 

 enumerated along with them, without destroying the 

 idea produced by the assemblage of the above-mentioned 

 genera. In a similar manner the genus Iron-ore is con- 

 nected on one side with the genus Manganese-ore, on the 

 other side with the genera Chrome-ore, Cerium-ore, Urani- 

 um-ore, Tantalum-ore, Copper-ore, Scheelium-ore, Tin-ore, 

 Zinc-ore, and Titanium-ore. Thus likewise round the ge- 

 nus Feld-spar are assembled the other genera of Spars un- 

 der similar circumstances. Every groupe of this kind 

 which is an assemblage of genera similar to each other, is 

 an order. 



These orders are as distinct from one another, and as re- 

 markable as the genera in the Mineral Kingdom, but they 

 require also, like these, to be observed in nature. They re- 

 present in the Mineral Kingdom the natural families of the 

 Vegetable Kingdom ; and their reception afld determina- 

 tion in the one and the other, depends upon the same prin- 

 ciple. 



The orders, like the genera, must not be compared with 



VOL. I. Y 



