Agricultural Chemistry. 287 



weight, of a thin soil from Dorsetshire, absorbed and retained in 

 a very fixed and permanent form of combination, on an average of 

 four experiments, 348 parts, by weight, of ammonia, and that the 

 same weight of a light red soil from Berkshire absorbed 157 

 parts ; the same weight of a stiff white clay 282 parts, by weight, 

 of ammonia. 



If we now calculate how much ammonia one acre of each of 

 these soils can take up to the depth of 12 inches, in addition to 

 that already contained in it from long exposure to the air, taking 

 the specific gravity at 1'5, we find that — 



Lbs. Amruouia. 



One acre of the tliin land of Dorsetshire can take np .. 20,880 



„ light red soil, Berkshire. 0,420 



„ stiff white clay .. .'. 17,040 



These numbers express, not how much ammonia the soils 

 contain, but how much they are still capable of absorbing from 

 the air and from the rain, in addition to what was already present. 

 They express the power of absorption of these soils for am- 

 monia ; and this can even be increased by ploughing or digging 

 and by draining, which allow an easier access to the air and to 

 the rain. 



The fact that the soil contains enormous quantities of ammonia, 

 derived from the atmosphere, was thus known with certainty. 

 But the discovery that the soil can remove from rain-water the 

 ammonia dissolved in it, belongs to Thomas Way.* I regard this 

 as a very important discovery, which satisfactorily explains the 

 gradual accumulations of large quantities of ammonia in culti- 

 vated soils. 



I have ascertained by a series of experiments (' Annalen des 

 Chemie and Pharmacie,' vol. 94), that the very calcareous soil 

 near Munich possesses, in an equal degree with clay soils or clay, 

 the power of removing ammonia from water. This calcareous 

 soil contains, 1 may state here, invariably nitrates, which are 

 almost entirely absent from clay soils. Even the calcareous soil 

 of Cuba, on which tobacco is grown and which has never been 

 manured, contains large quantities of nitric acid. 



If my conclusions of 1843 be considered along with the deter- 

 minations of the amount Of ammonia in arable soil, which I caused 

 to be made in 184G, it is easy to see how I felt myself compelled 



♦ This fact was first ascertained by mc in the course of some experiments under- 

 taken for .the express purpose of ascertaining tlie comparative loss of ammonia 

 sustained by the washing of rain after manuring soils with liitierent salts of am- 

 monia, especially tlie carbonate and sulphate. The analyses were performed by 

 that vci y accurate chemist Mr. Spencc of York, and showed uimiistakeably the 

 great athnity of almost any cultivated soil for ammonia. Tiiese experiments were 

 made more than two years before the commenccmeut of Mr. Way's investigation. 

 A brief account of them is given in tliis Journal, vol. xi. p. G8.— fl. S. T. 



