Agricultural Chemistry. 321 



My views are different and may be thus expressed : — A 

 certain mass of silver and gold circulates in the world, and 

 the art of becoming rich consists in knowing the way to divert, 

 from the main stream, an additional brook to one's own house. 

 In like manner, there circulates, in tlie air and in the soil, a rela- 

 tively inexhaustible quantity of the food of plants ; and the art of 

 the farmer consists in knowing and using the means of rendering 

 this food efficient and available for his crops. The more he is 

 able to divert from the moving stream (the air) to the immoveable 

 promoter of his production (the soil of his fields), the more will 

 the sum of his wealth and of his products increase. 



I liad advised farmers not to bestow their chief attention on 

 that element of the food of plants which the heavens constantly 

 shower on our fields, but rather to care especially for those con- 

 stituents, which are not restored spontaneously, or without our 

 assistance ; and considering that I was well aware what enormous 

 quantities of ammonia are contained in the soil, which ammonia 

 Avas inefficient if the conditions of its efficiency were wanting, it 

 is easy to see why I was led to look for the causes of the efficacy 

 of fallow in other quarters, and not in the increase of the amount 

 of ammonia in the soil. 



In direct contradiction to my opinion, and after they had pre- 

 mised (p. 488) that in my book, and especially in the chapter on. 

 fallow, I had not said a single word of the accumulation of atmos- 

 pheric food for plants, that is, of nitrogen, in the soil, these 

 agricultural chemists assert as follows: — "We maintain (p, 487) 

 that it is by the amount of this accumulation of available atmos- 

 pheric food of plants loithin the soil, rather than by the amount 

 of liberated (proper) soil constituents, that the increased produce 

 of grain will be measurable." Again (p. 488) : " We have our- 

 selves, on more than one occasion, called attention to the former 

 influences, and also to the fact that a study of the properties of 

 the soil in relation to the atmospheric food of plants promised to 

 be of more value to agriculture than that of the mere determinaticm 

 of its percentage composition in the mineral food of plants." 

 And as they find, in my 'Principles' (p. 106), a sentence which, 

 verbatim from p. 82 of the German edition, is as follows : "But 

 to prepare the soil, by art, so that it is enabled to collect from the 

 atmosphere and the sources offered to plants by nature a maximum 

 of nitrogen ; — this is a problem worthy of scientific agriculture ;" 

 they add, (p. 488), " We are happy to have now the sanction of 

 Baron Liebig himself" They thus endeavour to make others believe 

 that they liavc taught me the fact of the presence of ammonia in 

 the soil (which, ten years ago, I determined in twenty-two different 

 soils), and tliat 1 ascriljed to the ammonia which the soil acquires 

 in fallow some specially predominant influence. 



VOL. XVI r. Y 



