AMMONIA ABSORBED BY THE SOIL. 73 



by the union of the ammonia with acids, are like the gas 

 itself, exceedingly soluble in water. Two results of this 

 property follow. The carbonate of ammonia which is 

 formed in the atmosphere by the union of the ammonia and 

 the carbonic acid, is readily dissolved, and is washed down 

 and brought to the earth by the rains and dews; the soil is 

 thus supplied with most useful food for the crops, while 

 the air is freed from a noxious substance and is purified for 

 the use of mankind and animals. Also whatever combina- 

 tions of ammonia are formed in the soil, are dissolved and 

 diffused through it by the rains, or other moisture derived 

 by condensation, and are carried everywhere in all direc- 

 tions by the movements of this moisture among the fine 

 particles of the soil. 



Fourth. As this gas is readily absorbed by porous earthy 

 matter, it is readily taken up by the soil and held in reserve 

 to be yielded up to the roots of plants with the water of the 

 soil which draws upon this source for a supply. Hence the 

 ammonia yielded by the decomposing organic matter of the 

 soil, is held safely but loosely among the finest particles of 

 the soil as an intermediate deposit, to be drawn upon for 

 future use as it may be required by the crops. This prop- 

 erty of fine dry soil is of great importance to the farmer for 

 it is exerted to a large extent. All porous substances as 

 has been previously explained have, among other proper- 

 ties, that of oxidizing organic matter. Hence it has been 

 found that the dry earth used as an absorbent in the do- 

 mestic earth-closets and urinals, so rapidly and effectively 

 oxidize these matters which are rich in nitrogen, and in 

 which the nitrogen is easily converted into ammonia, that 

 they wholly disappear, and the dry earth after having been 

 used repeatedly nine times in the closet, with alternate pe- 

 riods of rest, still gives no indication of having been used 

 for this purpose in the slightest offensiveness, or appearance 

 of containing any disagreeable substance. The organic mat- 

 ter has disappeared; having evidently been resolved by ox- 

 idation into its elements and the gases having been absorbed 

 and held by occlusion in the interstices of the porous earth. 



