9^0 CHTMrSTKT APPLIED TO AGRICULTURE. 



should flow through soils free from metallic salts or earths ; 

 and that they should have traversed, before being used in 

 agriculture^ a sufficient space to have become impregnated 

 with a due portion of atmospheric air. 



Streams may not be pure, and yet may be very serviceable 

 for watering the soil, especially if they carry, or hold in 

 solution, certain salts favorable to plants, and some animal 

 or vegetable substances. In this case they possess double 

 virtue, and produce doubl?^ effect. 



Waters may be divided into three classes ; the first com- 

 prehending those that are charged with animal matter ; 

 the second, those which hold in solution some of the prin- 

 ciples of vegetables ; and the third, the pure waters, or 

 those which contain salts in but small quantities. 



The waters of the first class are the most active ; and 

 amongst them, those which are loaded with the sweat of 

 wool, or with the ammoniacal combinations arising fi-om 

 the fermentation of powdered bones, of shavings of horn, 

 or fragments of wool, hold the first rank. When employed 

 in their dry state, as manures, these substances produce 

 their eff*ects very slowly, but exercise a much more ener- 

 getic action when, during decomposition by putrefaction, 

 their products are absorbed by water as fast as formed, 

 and immediately conveyed to the plants. The soft, fleshy, 

 or liquid portions of animal substance do not produce so 

 lasting an effect ; tlieir decomposition is too rapid for their 

 action to be continued for any length of time. 



The waters of the second class, those that are charged 

 with some of the products of vegetation, either natural or 

 arising from decomposition, form very good manures. 



When plants have yielded to water all their soluble por- 

 tions, the subsequent decomposition of their insoluble 

 fibres furnishes new soluble products, which serve for 

 nourishment ; water imbibes these as fast as they are 

 formed, and transmits them to the plants with which it 

 comes in contact. In this manner dead plants supply 

 food to the living, and all the elements composing the first 

 are found differently combined in the last. 



When natural vegetable products, or those arising from 

 decomposition, are mixed with, or dissolved in urine or 

 the other animal fluids which are charged with salts, the 

 effect upon vegetation is much increased, because, in ad- 

 dition to exciting the digestive organs of plants, these salts 

 dissolve some substances which could not in their original 



