2 INTRODUCTION. 
be defined with precision: and into whatever path we chance to 
strike, difficulties from the very nature of the case are unavoidable. 
The Natural Sciences relate either to Nature and her several 
products considered by themselves: or they teach us so to apply 
those products as to contribute to our service, or to satisfy our 
wants. The latter are called practical natural sciences, the former 
theoretical. To the practical natural sciences belong especially 
Agriculture and Technology: and they are founded upon the 
theoretical, of which the truths are applied only im a degree propor- 
tioned to the particular object that is had in view. They may 
therefore be called Applied Natural Sciences. Of the pure, or 
theoretical Natural Sciences there are several. T’o them belong? 
Phenomenal Doctrine, Chemistry, and Natural History. What 
characterises such sciences and distinguishes them from each other 
lies less in the objects which belong to the province of each, than 
in the manner of considering them, and in the different direction 
of the enquiry. Metals, salts, earths belong as much to the province 
of Chemistry as to that of Natural History: but the chemist, in 
all these things, investigates only the matter and its properties, its 
affinities and combinations: the mineralogist is busied with their 
form, their natural occurrence, their classification. The chemist, 
moreover, investigates those elements which occur in nature only 
in combination with other matters: such elementary substances are 
excluded from the province of Natural History. 
Whilst Physics investigate the common properties of bodies, and 
the motions by which a temporary change is effected in their 
condition, Chemistry enquires into their component parts, the 
special properties of each elementary substance, and its various 
combinations with other elementary substances. Natural History, 
finally, arranges the bodies occurring in Nature according to form. 
In a certain sense, therefore, it may be termed a special Phenomenal 
Doctrine: but its essence lies in describing and classifying. It is 
ordinarily limited to the bodies which occur upon the surface of 
our earth, or at small depths below and accessible by mining: but 
it is by no means necessary thus to limit it. It depends upon the 
1 [ Natur-lehre, The vast body of observed facts throughout nature “ bound together 
_ under the form of laws and principles.” Vid. WHEWELL’S History of the Inductive 
Sciences, and his Philosophy of the Inductive Sciences, passim.| 7'r. 
