various important subjects in Mineralogy. 211 
out being influenced by external powers, during the whole of 
their life, or during a part of its continuance ; nor are they so 
exactly or strictly separated as in the mineral kingdom, where 
they are permanent from the very moment in which the develop- 
ment of the bodies has been completed, and can be altered 
only by the influence of external powers. In this kingdom, 
therefore, they form a basis of absolute constancy , upon which 
a science may be founded, as unalterable as the properties them- 
selves ; and if, therefore, we should attach a particular value to 
their consideration, in any one of the three departments of Natu- 
ral History, and, confining ourselves to this consideration, yet ar- 
rive at accuracy and certainty in our determinations or results 
in general, it would be especially, and by preference, to Miner- 
alogy that the method in question would apply. 
Nobody would think of denying the constancy of the results 
of Chemistry, provided they have been acquired with the neces- 
sary accuracy. For, as surely as a mineral retains the form and 
angles of its crystals, its hardness, specific gravity, and other 
properties, to the very moment of its decomposition ; with the 
same degree of certainty does it continue to possess the same 
chemical constitution during that period, without the slightest 
change. The only difficulty is to ascertain the true proportions of 
the mixtures, which in many instances have not yet been dis- 
covered, as is demonstrated by the differences in the results of 
analyses of the same mineral, of which every day furnishes us 
wfith new examples. But the human intellect requires, that, in 
nature, the correct results of analysis, or the chemical constitu- 
tion of bodies, should be as constant as those properties which 
are considered in Natural History ; for, should this not be the 
case, it would not be worth our while to occupy ourselves with 
them, for any other than technical or economical purposes. 
This, however, depends upon the essence of the two sciences 
themselves ; and so far from throwing a disadvantageous light 
upon chemical inquiries, it will only require to be rightly under- 
stood, or viewed from the proper side, to prevent us from form- 
ing erroneous notions in regard to the extent of Natural His- 
tory and Chemistry, two sciences presenting entirely different 
objects, although operating upon the same bodies. It is not 
difficult in Natural History to arrive at the requisite exactness 
