C xli 3 
fering us back to a tafte that was formerly m 
vogue ; and which, though we do not defpifej 
yet we negleSi, The fecond feems to have hur- 
ried himfelf too much, mixing together fome 
irrefiftable truths, with a greater number of 
opinions, not yet demonftrated, or mere con- 
jedlures \ which is running on /after with a theory 
than experiments will permit \ whereby nature^ 
which is the chief pointy will at the end be 
loft. 
Therefore, that no fondnels for novelties, in 
confequence of thefe new worksj or others of 
the like nature, which may hereafter be pub- 
lifliedj 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, publillied this Effay, even before 
I have had time and leifure to reduce it into a 
perfed; fyftem : I do not pretend that it is a 
compleat one, by which we can with certainty 
divide mineral fubilances, and afterwards re- 
duce them into order. I have chiefly intended 
it as a bar or oppofition 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 clafjes^ genera^ and fpecies^ as animals and 
vegetables are ; they do not coniider that in the 
two laft kingdoms of nature there are but fel- 
