[ xii ] 



bring us back to a tafte that was formerly ifl 

 vogue , and which, though we do not defpife, 

 yet we ?iegle£i. The fecond feems to have hur- 

 ried himfelf too much, mixing together fome 

 irfefiftable truths, with a greater number of 

 opinions, not yet demonftrated, or mere con- 

 jectures -, which is running on f after with a theory 

 than experiments will permit -, whereby nature, 

 which is the chief point, will at the end be 

 loft. 



Therefore, that no fondnefs for novelties, in 

 confequence of thefe new works, or others of 

 the like nature, which may hereafter be pub- 

 limed, may again divert our attention from the 

 only method of obtaining any knowledge of the 

 Mineral Kingdom \ which has with fo much 

 pains at length been difcovered, and has al- 

 ready been a little entered upon , I have, 

 prompted either by felf-love, or a more gene- 

 rous motive, publifhed this Effay, even before 

 I have had time and leifure to reduce it into a 

 perfect fyfiem : I do not pretend that it is a 

 compleat one, by which we can with certainty 

 divide mineral fubftances, and afterwards re- 

 duce them into order. I have chiefly intended 

 it as a bar or opposition to thofe, who imagine 

 it to be an eafy matter to invent a method in 

 this fcience, and who, entirely taken up with 

 the furjace of things^ think that the Mineral 

 Kingdom may with the fame facility be reduced 

 into clafes, genera^ and fpecies, as animals and 

 'vegetables are ; they do not coniider that in the 

 two laft kingdoms of nature there are but fel- 



dom r 



