142 CLASSIFICATION. 



It has been already seen, that there exists but one form of cleav- 

 age in a species, and that this is the same both in the crystallized and 

 semi-crystallized individuals of that species; and, moreover, that it 

 is identical with, and in reality constitutes the primary form or sys- 

 tem of crystallization in the species. Consequently, the system of 

 crystallization affords the foundation of a division among the minerals 

 of the present class, with the same facility as in the first class. And 

 we may expect to find, from the known fact that many of the species 

 in the mineral kingdom embrace both crystallized and semi-crystal- 

 lized minerals, that the same species will exist in both classes, and 

 when this takes place, the division of both being upon one principle, 

 we shall find them contained in the same order in both. For ex- 

 ample, Galena occurs in the order of the Cube in the first class, and 

 again in the order of the Cube in the second; Sulphate of Strontian 

 in the order of the right rhombic Prism in the first, and again in 

 the same order in the second, &c. 



. 112. DIVISION OF THE UNCRYSTALLIZED CLASS 

 INTO ORDERS. 



Uncr} stallized minerals are divisible into orders, depend- 

 ing upon the state of aggregation existing among their par- 

 ticles. 



Three divisions are thus created, according as the minerals of this 

 class are solid, liquid or gaseous. 



The present arrangement is not liable to any objection, on the 

 ground that the natural relations among the species have been dis- 

 regarded, much less that chemical affinities are overlooked. It is 

 to be tested only, as it does, or does not, afford the most direct means 

 in leading to the names of unknown minerals. The properties upon 

 which it is founded are of easy observation and possessed of sufficient 

 constancy : their examination does not involve a knowledge of other 

 sciences, or require an inconvenient minuteness of detail. What is 

 more easy, for example, than to settle whether a mineral be crystal- 

 lized, and if not, whether it yield a regular solid by cleavage ? These 

 are the only questions to be solved in the determination of the class. 

 And if due attention has been paid by the pupil to the section on Crys- 

 tallography, the orders in the two first classes may be ascertained 



