The food on which they have been brought up has been gathered from the soil--the grass, the hay, the root crops, the linseed, the barley, the oats. And how much intellect, from the earliest dawn of civilisation, has been lavished upon the soil!--how many branches of knowledge are at this moment uniting their strength to develop its latent capabilities! Geology yields the raw materials upon which, in after ages, the toils of the husbandman are expended. She explains what are the variations in the natural quality of these materials; how such variations have arisen; where they lead to increased, and where to diminished fertility; how and where the still living rocks may contribute to the improvement of the dead earth which has been formed from them; and how, in some apparently insecure regions, the unsleeping volcano showers over the land, at varying periods, the elements of an endless fertility. Mineralogy lends her aid to unravel the origin, and nature, and wants, and capabilities of the soil; and, as the handmaid and willing follower of geology, dresses and classes the fragments which geology has let fall from her magnificent formations. But chemistry, especially, exhausts herself in the cause of the husbandman. No branch of rural art, as we shall see, is beyond her province and control. All that the soil originally derives from geologic and mineral materials, chemistry investigates; all that these substances naturally become, all that they ought to yield, how they may be persuaded to yield it; by what changes this is to be brought about; by means of what agencies, and how applied, such changes are to be induced:--chemistry busies herself with all this, and labours in some sense to complete, for the purposes of rural art, the information which geology and mineralogy had begun.