94 CHEMISTRY OF NATURAL WATERS. [IX. 



meteoric waters hold in solution, besides nitrogen, oxygen, 

 carbonic acid, ammonia, and nitrous compounds, small quan- 

 tities of solid matters which were previously suspended in the 

 form of dust in the atmosphere. After falling to the earth, 

 these same waters become still further impregnated with for- 

 eign elements of very variable nature, according to the con- 

 ditions of the surface on which they fall. 



2. Atmospheric waters, coming in contact with decaying 

 vegetable, matters at the earth's surface, take from them two 

 classes of soluble ingredients, organic and inorganic. The 

 waters of many streams and rivers are colored brown with dis- 

 solved organic matter, and yield, when evaporated to dryness, 

 colored residues, which carbonize by heat. This organic sub- 

 stance, in some cases at least, is azotized, and similar, if not 

 identical, in composition and properties with the apocrenic 

 acid of Berzelius. The decaying vegetation, at the same time 

 that it yields a portion of its organic matter in a soluble form, 

 parts with the mineral or cinereal elements which it had re- 

 moved from the soil during life. The- salts of potassium, cal- 

 cium, and magnesium, the silica and phosphates, which are so 

 essential to the growing plant, are liberated during the process 

 of decay ; and hence we find these elements almost wanting in 

 peat and coal. (See on this point the analyses by Vohl of 

 peat, peat-moss, and the soluble matters set free during its 

 decay; Ann. der Chem. und Pharm., CIX. 185. Also Liebig, 

 analysis of bog-water, Letters on Modern Agriculture, p. 44 ; 

 and in the second part of this paper, the analysis of the water 

 of the Ottawa River.) 



3. At the same time an important change is effected in 

 the gaseous contents of the atmospheric waters. The o\ 

 which they hold in solution is absorbed ' by the decaying 

 organic matter, and replaced by carbonic acid ; while any 

 nitrates or nitrites which may be present are by the same 

 means reduced to the state of ammonia (Kuhlmann). l.y thus 

 losing oxygen, and taking up a readily oxidizable organic mat- 

 ter, these waters become reducing instead of oxidizing media 

 in their further progress. 



