MOULDERING OF VEGETABLE SUBSTANCES. 317 



tate of a brown or black colour, from which the 

 acid can be removed with difficulty by means of 

 water. When this precipitate,, after having been 

 washed with water, is brought whilst still moist 

 under a receiver filled with oxygen, the gas is 

 absorbed with great rapidity ; and the same thing 

 takes place when the precipitate is dried in the air. 

 In the perfectly dry state it has entirely lost its 

 solubility in water, and even alkalies dissolve only 

 traces of it. 



It is evident, therefore, that boiling water extracts 

 a matter from vegetable mould, which owes its solu- 

 bility to the presence of the alkaline salts contained 

 in the remains of plants. This substance is a 

 product of the incomplete decay of woody fibre. 

 Its composition is intermediate between woody fibre 

 and humus into which it is converted, by being 

 exposed in a moist condition to the action of the 

 air. 



ON THE MOULDERING OF BODIES. PAPER, 

 BROWN COAL, AND MINERAL COAL. 



The decomposition of wood, woody fibre, and all 

 vegetable bodies when subjected to the action of 

 water, and excluded from the air, is termed moul- 

 dering. 



Wood- or brown-coal and mineral coal, are the 

 remains of vegetables of a former world ; their 

 appearance and characters show, that they are pro- 



