436 Action of the Atmosphere upon neicly-deepened Soil. 



dry soil is thrown, and the bottle then shaken, all ammoniacal 

 smell will disappear. Way attributes this property, in a great 

 measure, to the double silicate of alumina and lime, which he 

 found had so great an avidity for carbonate of ammonia that a 

 few grains of the lime-silicate placed under a bell-jar, along with 

 some pieces of dry carbonate of ammonia, in a few hours ab- 

 sorbed between 2 and 3 per cent, of the volatile alkali ; the car- 

 bonic acid of the carbonate of ammonia combining with the lime 

 to form carbonate of lime, while the ammonia forms, with the 

 alumina, a double silicate of alumina and ammonia. {Eng. 

 Agricult. Journ., XXIX. p. 138.) 



De Saussure observed that sulphate of alumina exposed to the 

 air passed into ammoniacal alum. Vauquelin also detected 

 ammonia in the oxide of iron produced by the exposure of that 

 metal to the action of air and water ; and Chevallier and Bous- 

 singault found it in the native oxides of iron ; Austin also states 

 that it is always present when iron is oxidated by air and water. 

 Iron, however, according to Guibourt, has the power of decom- 

 posing water when it rusts, abstracting the oxygen and liberating 

 the hydrogen, and it is possible that ammonia may be formed in 

 the process ; be this as it may, howevei", peroxide of iron, like 

 other porous bodies, greedily absorbs ammonia and many other 

 gaseous substances. 



The organic matters of the soil have also a strong affinity for 

 this gas ; peat absorbs a large quantity, and so great is the at- 

 traction of the humic and other organic acids of the soil for 

 ammonia that they can hardly be freed from it. {Anderson.) 



In addition to the ammonia which the atmosphere supplies 

 directly, it furnishes it also indirectly by its action upon the 

 nitrogenised matters that may be in the soil ; this organic matter 

 may be decomposed by the conversion of its nitrogen either into 

 ammonia or into nitric acid. Dr. K. A. Smith, of Manchester, 

 has shown that, if the soil is very alkaline and moist, the conver- 

 sion of the organic matter into ammoniacal compounds is very 

 rapid. He put some soil not very rich in organic matter into 

 this condition by the assistance of a little ammonia, and the con- 

 sequence was the rapid occurrence of a very intense putrefactive 

 decomposition. In a paper to the Philosophical Society of 

 Manchester he showed that, through the rapid decomposition of 

 organic matter by moisture and heat, ammonia is formed so 

 abundantly that in hot Aveather, on peat-land, it may be found 

 perceptible directly by the senses. 



An important action of the ammonia is its power of dissolving 

 the mineral matter of the soil, Kuhlman, in reference to this, 

 writes, " In order fully to appreciate the effect of ammoniacal 

 salts, it is necessary to point out that they promote the entrance 



