288 Agricultural Chemistnj. 



to relinquisli the views I entertained at a period previous to 1843. 

 These analyses of soils, as well as those made in Prussia, in 

 Russia, and, at a still later period, again by myself, prove in the 

 most incontestable manner that the fundamental proposition of 

 Messrs. Lawes and Gilbert, namely, " tliat the quantities of Jiitrog en 

 Schick are supplied to pla7its hy the natural sources of that element 

 do not suffice for the requirements of a full crop of xolieat^'' has no 

 foundation whatever. These natural sources supply tlie wheat 

 plant with a hundred times, nay often a thousand times, more 

 nitrog'en than it requires for the fullest development. 



It follows inevitably that all the conclusions which these gen- 

 tlemen have established on this fundamental proposition are 

 erroneous, and cannot be maintained. 



It follows further that all the experience and all the facts which 

 they endeavoured to refute, by means of this fundamental propo- 

 sition, and which they believed themselves to have refuted, have 

 not been refuted, and must, in the mean time, be maintained. 



In my book I have expressed the opinion that the soil of a 

 country cannot, by means of cultivation, be exhausted of nitrogen, 

 because nitrogen is not a true constituent of the soil, but a con- 

 stituent of the atmosphere. It is only lent to the soil ; and what 

 the soil loses in nitrogen at one point is restored to it by the air, 

 which is everywhere : consequently the exhaustion or loss of fer- 

 tility of our fields cannot depend on a deficiency of nitrogen. 



I have been led to this opinion by the consideration of the cul- 

 tivation of entire countries or districts (such as the Valley of the 

 Nile, Switzerland, Holland) ; and the same considerations, if 

 applied to things nearer home, will probably convey to all who 

 attend to them a full conviction of the truth of the opinion to 

 which I have referred. 



From the daily consumption of food Messrs. Lawes and Gilbert 

 calculate that the 2i millions of inhabitants of London (' Journal 

 of the Society of Arts,' vol. iii. p. 272) annually consume upwards 

 of 25i millions of pounds of nitrogen; and the composition of 

 their solid and liquid excreta proves that in these last upwards of 

 17 millions of pounds of nitrogen, chiefly in the form of ammonia, 

 are conveyed to the sea, while the greater part of the remainder 

 returns to the atmosphere. This estimate is rather under than 

 over the truth. In Liverpool, Newcastle, Bristol, Dublin, Glas- 

 gow, and all the large and small towns of Great Britain, the state 

 of matters is precisely the same. 



If it were possible for a man to rise to such a height as to 

 survey at one glance the entire British Isles, this man, if the am- 

 monia were visible, would perceive that a mighty stream or current 

 of nitrogen flows daily from the land to the sea and the atmos- 

 phere, amounting in a year to 2 million of cwts. ; that what is 



