78 GEATES. * 



Those which already had existed in plants, combined with 

 vegetable acids. These last, by decomposition, escape as 

 carbonic acid, or in acid vapors and water, while the bases, 

 or earths and oxides with which they were combined, 

 remain, and are immediately seized upon by the forming 

 geine ; while the uncombined geine passes to the state of a 

 brown coal-like powder. 



116. The properties of this brown powder of mould are, 

 1st. Partial solubility in water. Cold water dissolves only 

 about one twenty-five-hundredth part of its weight, hot 

 water a little more. 2d. It is a perfectly neutral substance, 

 exhibiting neither acid, nor alkaline properties, but all alka- 

 lies develop it in acid properties. In this state it is termed 

 geic or humic acid. It is evident, therefore, that geic or 

 humic acid can never exist free in soil, so long as free bases 

 are there present, as lime, alumina, iron, &c. It is produced 

 by the action of alkaline bases, and immediately combines 

 with them, forming salts, which are termed geates. 



117. A third property of the brown powder of mould is, 

 that after alkalies have acted on it, and developed acid prop' 

 erties, its solubility in water is considerably increased, while 

 it continues in a moist state. If dried, in this acid state,, it 

 becomes almost insoluble in water. 



118. The geates found in soil have the following charac- 

 ters : 1st. All the alkaline geates are very soluble in water. 

 The solution is of a brown color, according to its strength, 

 from a light brown to a deep coffee color, or almost black ; 

 acids precipitate this solution, and the geine falls in light 

 brown flocks, exceedingly bulky. This precipitate may be 

 washed in water, rendered a little acid; but simple water, 

 in consequence of the great solubility of geine, developed 

 by its combination with alkali, will dissolve nearly all the 

 precipitate. 



