SOILS. 21 



the powers of lime and other mineral agents, and distinctly 

 comprehend the putrefactive and oxygenating processes, as well 

 as the consequences resulting from the action of fire on the 

 vegetable fibre or matter contained in the soil." 



A judicious farmer, when he fixes upon a spot for cultiva- 

 tion, will endeavour to ascertain the relative proportion or 

 combinations of the various earths constituting the soil he is to 

 till in what proportions they severally abound, and the nature 

 and extent of the vegetable matter existing in the soil. Pos- 

 sessing this information, he will be enabled to administer to 

 each part of his farm those particular substances necessary to 

 render it a rich and fertile mould. 



"When we regard the distribution of plants in different 

 regions, we perceive that this is determined by causes which 

 have little relation to the nature of the soil on which the 

 plants grow. The soils of all countries are, in their essential 

 characters, alike. The same mineral masses, composed of the 

 same substances, exist over all the world, and yield, by their 

 disintegration or decomposition the same materials for form- 

 ing soils. 



"Yet, although the mineral matter of the soils of all coun- 

 tries is thus similar in its constituent parts, it is altogether 

 different with the vegetation by which these soils are charac- 

 terized. Every zone, from the equator to the polar circle, is 

 distinguished by a different vegetation, and different regions 

 have their peculiar natural plants. 



"Among the natural causes which effect the vegetation of 

 countries, the influence of Temperature is that which is the 

 most obvious to the senses. When we pass from a warm coun- 

 try to a cold, we perceive a change in the whole character of 

 the vegetation. We cannot ascend a mountain without find- 

 ing such a change in the character of the plants produced, and 

 in the vigour with which they grow, dependent upon the change 

 of atmosphere." 



The degree of Moisture, too, the distance or proximity of 

 the sea, and other circumstances connected with the climate 

 and physical condition of the country, affect the nature of its 

 vegetable productions, and show, that the influence of soil, 

 with respect to the kinds of plants produced, is entirely sub- 

 ordinate to that of temperature, and the effects of climate. 

 Water constitutes a large portion of all plants without which 

 they either become stunted in their growth, or perish yet 

 water alone, without the addition of other substances, will not 

 sustain them, much less bring them to perfection. 



It is generally known, that soils possess the power of ab- 

 sorbing moisture (or water) in different degrees. This power 

 depends more upon the geine of soils than any other prin- 



