Vlil PREFACE. 



ployed, the inconvenience of consulting an index must ne- 

 cessarily have been encountered. 



But while the alphabetical distribution has the advantage 

 at least, of being independent of all scientific arrangement 

 concerning whose present existence many entertain doubts, 

 the two tabular views, one at the commencement of this 

 volume, and the other at the conclusion of the second, will 

 present the species grouped in accordance with two classes 

 of affinities, the first, the natural-historical, the second, the 

 chemical, resemblance. In the construction of these tables, 

 I cannot, of course, suppose that I have acquitted myself 

 to the satisfaction of all, when I have but so imperfectly 

 satisfied myself. 



The chemical arrangement, however, is such as the pres- 

 ent state of chemical science seemed to force upon me 

 without much choice. A more extensive and accurate 

 analysis of minerals, however, will undoubtedly produce 

 in it many changes, while also it will permit the composi- 

 tion of a considerable number of species, now left in un- 

 certainty, to be expressed with atomic precision. 



Both in this tabular view, and elsewhere in the work, I 

 have refrained from adopting the algebraical language of 

 BERZELIUS for denoting the chemical constitution of min- 

 erals, although it would have afforded much convenience 

 in the present state of chemical nomenclature, more par- 

 ticularly in relation to isomorphous compounds, because 

 I have every where sought to exclude whatever has 

 an abstruse and forbidding air ; knowing that many have 

 been discouraged from entering upon this pleasing and fa- 



