104 THE SOIL. 



In a stagnant pool or bog are gradually collected 

 the remains of dead generations of plants, the roots of 

 which have drawn a quantity of mineral matter from a 

 certain depth of the soil. These vegetable remains un- 

 dergo decomposition at the bottom of the pools, and 

 their inorganic elements, or ash-constituents, are dis- 

 solved by the aid of carbonic acid, and perhaps also of 

 organic acids. They remain dissolved in the water, 

 when the surrounding mud and the earth in contact 

 with this solution have been completely saturated with 

 them. 



Scherer found in the three wells at Briickenau all 

 the substances contained in the water above-mentioned, 

 of the Botanic Garden pond, besides acetic, formic, 

 butyric and propionic acids. The mountains all around 

 Briickenau are formed of variegated sandstone (Bimter 

 sandstein} ; the vegetation of the whole surrounding 

 country is most luxuriant, resembling the primeval for- 

 ests ; there are numerous oak-lands and beech-lands, 

 with trees nearly a thousand years old. Hence Scherer 

 is led to attribute the composition of the well-water at 

 Briickenau to the solvent action of rain percolating 

 through a humose soil rich in decaying vegetable sub- 

 stances. (' Annal. der Chem. und Pharm.' i. c. 285.) 



It is clear that wherever conditions have been at 

 work similar to those under which the bog-water in the 

 Botanic Garden of Munich and the wells of Briickenau 

 have been formed, the water found on the surface of 

 the earth, in pools, springs, or brooks, will contain in 

 the most varying proportions nutritive elements useful 

 to plants, such as phosphoric acid and potash, which 

 are not found in other waters. In like manner, an 

 arable soil rich in vegetable remains, in which, from 

 the processes of decay incessantly going on, products 

 of an acid character are generated, will be able to give 

 up, to the rain-water percolating through it, phosphoric 

 acid and alkalies, which are thus carried down to the 

 deeper layers, and appear in the drainage water. The 

 quantity of these substances dissolved in the water will 

 depend upon the condition of the soil on which the 



