414 
Book III. 
DESCRIPTION OF 
termission. The fruit of these labours has been the 
discovery of no less than six new earths and eight new 
metals ; besides a vast number of useful minerals which 
had been formerly unknown or disregarded. 
The science of mineralogy includes under it three 
different topics : 1. The method of describing minerals 
with so much accuracy and precision, that they may be 
easily distinguished from each other. 2. A systematic 
arrangement of minerals.. 3. The art of analysing mi 
nerals. These three topics shall form the subject of 
the three following Chapters. 
CHAP. I. 
OF THE DESCRIPTION OF MINERALS. 
NoTHING, at first sight, appéars easier than to de 
scribe a mineral, and yet, in reality, it is attended with 
a great deal of difficulty. The mineralogical descrip 
tions of the ancients are so loose and inaccurate, that 
many of the minerals to which they allude cannot be 
ascertained; and consequently their observations, how 
ever valuable in themselves, are often, as far as respects 
us, altogether lost. It is obvious, that to distinguish a 
mineral from every other, we must either mention some 
peculiar property, or a collection of properties, which 
exist together in no other mineral. These properties 
must be described in terms rigidly accurate, which con¬