244 ILLINOIS STATE HORTICULTURAL SOCIETY. 



FORMATION OF NITROUS ACID IN SOILS AND ITS DISTRIBUTION 



IN PLANTS. 



RKAl) IIY A. !■. S'liaVARl , BEFORE THE CHAMPAIGN COUNTY HORTICULTURAL SOCIETY, 

 , AT THE NOYEMBER MEETING, 1873. 



About a year ago there appeared in the Journal of the French Academy of Sciences 

 an article on Agricultural Chemistiy, in which the author, Mr. Jeannel seeks to establish 

 the following propositions : 



1. That nitrates or nitrites are naturally formed in a soil containing vegetable 

 matter in contact with the air. 



2. That it is possible to nourish plants with mineral solutions suitably prepared, so 

 that they will grow much better in pure sand moistened with such solution, than in the 

 best mold without them. 



The author informs us that these propositions coincide with the ideas of Boussing- 

 ault, published in 1856, when, in experimenting on the growth of the Helianthus, he 

 asserted that a plant assimilates its mineral constituents, and has no need of a soil con- 

 taining decaying organic matter; and that they also confirm the notion of Ville of the 

 agricultural importance of chemical manures. He might have added, that they are a 

 beautiful confirmation also of the views of Liebeg, as expressed in his celebrated theory 

 of mineral manures. 



On this occasion we wish to call particular attention to the first of these proposi- 

 tions, viz : the formation of nitrous acid and nitric acid in soils, not because it is new, 

 for the formation of nitre in soils is a fact familiar to every one, but because we behold 

 the fact no longer at a distance. We are brought, so to speak, face to face with the con- 

 ditions and agents necessary to the fact. The exjjeriments of Jeannel, which have 

 thrown so much light on nitrification, are these : If we take any ordinary vegetable 

 soil in wami weather, and wash it with pure water, the wash water will be found to 

 contain nitrous acid. If the washing be continued until some twelve times as much 

 water by weight as soil has been used, the water that passes through last will contain no 

 nitrous acid. If now, (and here is the important fact,) this soil be nearly dried, and 

 then washed again with pure water, the wash will be found to contain nitrous acid ; that 

 is, the simple drying of a soil, in some way produces nitrous acid. Now what ingredi- 

 ents of the soil are the immediate agents in the production of this acid? Is it the decay- 

 ing organic matter? is it the sand, the clay, the lime, the iron, the magnesia, the moisture? 

 is it one, or all of these constituents combined, that are concerned in the work? To 

 settle this question, Jeannel washed heathy and sandy soils, which did not effervesce 

 with acids, with pure water, allowed them to become nearly dry, and then washed again. 

 The wash water was found to contain no nitrous acid. It is neither the sand, the 

 organic matter, nor the moisture, nor all combined, then, that gave rise to nitrifi- 

 cation. He then mixed with the soils some pulverized marble, moistened the masses, 

 and allowed to dry. On washing again, he found distinct indications of nitrous acid. 

 In some way, then, the four constituents, lime, organic matter, sand and water, had given 

 rise to nitrous acid. Such are the experiments of Jeannel, which, so far as we are 

 infomied by his paper, were carried no farther, but which, judging from the proposition 

 already annouuced, left on his mind the impression that vegetable matter, as well as 

 lime, is in some way connected in the formation of this acid. 



His experiments suggested the following inferences : 



1st, That soils containing organic matter and carbonate of lime do, by the simple 

 process of drying, without the intervention of ammonia, induce the chemical union of 

 the oxygen and nitrogen of the atmosphere, and thus give rise with water to nitrous 

 acid. 



2nd, That soils destitute of lime, like those com]X)sed wholly of silicious sand, or of 

 peat, do not in diying produce nitrous acid. Such soils are therefore barren, and greatly 

 benefited by liming. 



