IV PREFACE. 



always possible to derive the satisfaction desired, from 

 others. Doubtful minerals would come back referred to 

 two or three species, or with a name followed by that mod- 

 est sign of ignorance the well known interrogation point. 

 Or if correctly referred, the descriptions of the author 

 would not in all cases coincide with the ipse dixit of the 

 umpire, and therefore left no certain verification in the case. 

 Thus, the determination of minerals was found to be not 

 only empirical, but often impracticable. 



The cause of this was sufficiently obvious. The classes 

 and subordinate divisions were founded upon such proper- 

 ties as prevented them from being available to the miner- 

 alogist, requiring the practice of a difficult department of 

 another science ; so that no one thought of employing them 

 in reducing a mineral to its place in the system. No sci- 

 entific process existed for leading the inquirer to the name 

 of an unknown mineral ; but it was left to the general de- 

 scriptions to perform a task to which, from the nature of 

 the case, they were incompetent. Indeed, it appears to 

 have been taken for granted by the authors of the minera- 

 logical treatises of that period, that students were in all 

 cases to acquire a knowledge of Mineralogy through teach- 

 ers and cabinets ; and that if, after being thus taught, it 

 should ever become necessary to determine a mineral, it 

 must be taken for that purpose to some professor of the 

 science. 



That the determinative part of Mineralogy was suffered 

 to remain so long in this condition, can only be explained 

 by the fact, that the study was chiefly cultivated by Chem- 

 ists ; who, not having experienced the advantages of the 

 methods of Natural History, were in a measure unconscious 

 of the embarrassments under which they labored. 



