THE SOUTHERN PLANTER. 



potash, as well as other bases, and that 

 indeed, the most important fertilizing ma- 

 terials were amenable to the law regulat- 

 ing the absorption of ammonia. Thus, 

 100 grains of clay, a sample of very te- 

 nacious white clay, from the plastic clay 

 formation, were found to absorb, from a 

 solution of caustic potash containing 1 

 per cent, of potash, 1-050 grains of pot- 

 ash. In this instance, the alkaline solu- 

 tion was not filtered through the soil, but 

 merely left in contact with it in the cold 

 for twelve hours. It therefore appears, 

 as has been shown, likewise, in many 

 other experiments, that the process of 

 filtration is unessential for the display of 

 this remarkable property, and that soils 

 simply brought in contact with alkaline 

 solutions, have the power of absorbing 

 a certain proportion of the alkaline sub- 

 stance. This absorption, moreover, was 

 found to be very rapid, if not instantane- 

 ous ; and it appears from this, that true 

 chemical combinations are formed in all 

 cases of absorption of this kind. 



Still more important than the facts re- 

 specting the rapid absorption of free al- 

 kalies by soils, is the observation made by 

 the same indefatigable philosopher, that 

 all cultivated soils possess likewise the 

 power of separating the ammonia, pot- 

 ash, and other alkaline substances from 

 their combinations with various acids. 

 Thus, when solutions of salts of ammo- 

 nia, of potash, magnesia, &c, were pass- 

 ed slowly through a layer of dry soils five 

 or six inches deep, it was remarked that 

 the clear liquid, after filtration, no longer 

 contained any of the ammonia or other 

 salts employed. The soluble alkaline 

 salts were thus retained in some form or 

 other in the soil, whilst the water in which 

 they were dissolved previously was pass- 

 ing through. A careful examination of 

 the soil experimented upon, and of the 

 water which had passed through it, and 

 originally contained, in solution, a salt of 

 ammonia or potash, &c, moreover, fur- 

 nished the important result that the alka- 

 line salt is not absorbed by the soil as 

 such, but that the latter, indeed, has a 

 decomposing power, which effects the 

 resolution of the salt into its acids and 

 alkaline base, which latter alone is retain- 

 ed by the soil during the process of fil- 

 tration, or simply by shaking the salt-so- 

 lution with a sufficient quantity of soil. 



If, for instance, a solution of sulphate of 

 ammonia, of moderate strength, is passed 



eight 



through a filter-bed of soil, five to 

 inches deep, it will be found that the am- 

 monia alone of the sulphate of ammonia 

 is retained, and the sulphuric acid, with 

 which the volatile alkali is combined, will 

 then be found passing through with the 

 water, generally though not always in 

 combination with lime. Or if the salt em- 

 ployed in the experiment was nitrate of 

 ammonia, a similar change will be effect- 

 ed by the contact of such a solution with 

 the soil ; the ammonia alone will be ab- 

 sorbed, and the nitric acid, with which 

 it was previously combined, will be con- 

 tained in the filtered liquid, in combina- 

 tion with lime. Other salts of ammonia, 

 as well as compounds of potash, magnesia, 

 &c , when passed in solution through a 

 soil, are subject to the same law which 

 determines the separation of ammonia 

 from its sulphate, and whatever the acid 

 may have been with which the alkaline 

 substance was originally combined, in 

 every instance it will be found that the 

 alkali alone is absorbed by the soil, whilst 

 the acid of the salt will pass through, 

 not in a free state, but united with lime 

 or other basic constituent of the soil. By 

 the simple process of filtration, or by 

 mere contact of the soil with solutions of 

 different alkaline salts, new compounds 

 are thus produced. That this remarka- 

 ble action is a trup chemical decompo- 

 sition, is clearly proved by the fact that 

 the quantity of lime which, in combina- 

 tion with'the acid of the ammoniacal salt, 

 passes into the filtered liquid, corresponds 

 exactly to that of ammonia removed from 

 it. Thus, when muriate of ammonia is 

 filtered through the soil, with which most 

 experiments were performed, the ammonia 

 was removed, and a corresponding quan- 

 tity of lime, in combination with muriatic 

 acid, was detected in the filtered liquid. 

 Sulphate of potash parted with its potash, 

 and sulphate of lime was produced ; ni- 

 trate of ammonia or potash, in the same 

 manner, gave rise to the formation of 

 nitrate of lime; whilst ammonia and pot- 

 ash were retained by the soil in quanti- 

 ties corresponding to the lime acquired by 

 the filtered liquid. 



Like the absorption of the free alka- 

 lies, that from the alkaline salt-solution 

 varies considerably in different soils ; and 



