C. T. JACKSON'S ADDRESS. 461 



to nourish plants, by aiding in the decomposition of carbonic 

 acid gas. 



A portion of the carbonic acid of the air is dissolved by rain, 

 and penetrates with it into the earth, and there aids in the de- 

 composition of the materials of granite rocks, forming carbon- 

 ates of potash and soda from the silicates of those bases. 

 Aquatic vegetation also feeds, in part, on the carbonic acid of 

 rain water, and absorbs the carbon, and gives out oxygen gas 

 to support the respiration of fishes, which soon return carbonic 

 acid to the water to repay the plants.* 



Thus nature performs a series of the most interesting chem- 

 ical experiments, and keeps up forever the circulation of the 

 life-supporting matters required by the two great living king- 

 doms. Ammonia of the air. Carbonate of ammonia has been 

 supposed to be a constituent of the general atmosphere, but 

 there is reason to believe that it exists only near the surface of 

 the earth, and arises from decaying animal matter, the effluvia 

 of which consist partly of this volatile salt. 



Many ammonia-producing organic matters, exist in rain and 

 snow water, and the first snow that falls is well entitled to the 

 name of the •' poor man's manure," for it brings down with it 

 "a very considerable proportion of ammoniacal matter, which 

 is found in the form of a yellow organic substance, which is 

 quickly converted by mineral acids into salts of ammonia. 

 This yellow matter found in snow and rain water, has been 

 named by Zimmerman, pyrrhine, and, according to the re- 

 searches of Dr. A. A. Hayes, it is the chief source of the 

 ammonia found in the atmosphere. The well known superi- 

 ority of rain water over spring water, as a fertilizer, may be 

 due to the presence of this highly nitrogenized and easily de- 

 composable organic matter in rain water. It is, as before ob- 

 served, especially abundant in the first rains, which fall after a 

 long drought, and hence, those rains produce such marvellous 

 effects, so far surpassing those produced by terrestrial or spring 

 water. (See Memoir on the supposed existence of ammonia 



*This operation of sub-aqueous plants I have witnessed on the coast of Lake Superior. 

 The lake water generally contains about two and a-half per cent, of its bulk of air dissolved 

 in it. Among aquatic plants, free oxygen is seen bubbling through the water. 



