PREFACE. Ill 



the exposition of the principles, notwithstanding its 

 high importance. It will only be necessary to ad- 

 vert to those passages in it, which refer more par- 

 ticularly to the arrangement of some of the de- 

 partments of the work itself. 



In the systematic nomenclature, introduced by 

 Professor MOHS, and employed in the present 

 work, the compound names and denominations 

 express the degree of connexion in which the spe* 

 cies stand to each other, and faithfully represent 

 their resemblance. In the trivial nomenclature, 

 the name applied to the species does not express 

 any thing of that connexion, and it must be a 

 single word, if it shall be convenient for use, in cases 

 where we do not intend to apply it in Natural History 

 to any scientific purpose ; consequently those are se* 

 lected which, according to the rules of . 241., may 

 be considered as unexceptionable, and are added to 

 the specific characters in the Characteristic, referring 

 at the same time to the page of the second and 

 third volume, where the species is more amply de- 

 scribed, and other synonymes added. Where no 

 good trivial names existed, the names or denomina- 

 tions used by Professor JAMESON in the third edi- 

 tion of his system, or those adopted by other Mine- 

 ralogical authors, or by Chemists, have been intro 

 duced in their place. 



The actual employment of the Characteristic to 



