On the Chemical Properties of Soils. 27 



It is one of the functions of soils to check the accumulation of 

 soluble fertilizing matters, and this function it performs in many 

 instances by rendering insoluble, or, to speak more correctly, by 

 greatly reducing the solubility of those important fertilizing 

 matters which would otherwise induce an unhealthy or abnormal 

 growth of plants. Considering the structure of the spongioles of 

 the roots of plants we readily comprehend how important it is 

 that such matter should be able to find its way into the vegetable 

 organism. Whilst thus it is the particular function of the soil 

 to prevent the loss of ammonia from manures, such as guano, 

 sulphate of ammonia, &c., which we are in the habit of applying 

 to the land, provision is made that the ammonia, when it becomes 

 fixed by the soil, should not be rendered so entirely insoluble 

 as to be of no direct benefit to plants. 



In short, all soils, clay as well as sand, store up ammonia with 

 great eagerness, and part with it reluctantly. 



SIXTH SERIES. ABSORPTION OF AMMONIA FROM A SOLUTION 



CONTAINING CHLORIDE OF AMMONIUM. 



In this series of experiments I endeavoured to ascertain the 

 amount of ammonia which soils of known composition absorb 

 from a standard solution of sal-ammoniac in water. 



The solution used in the following experiment contained 

 79*80 grains of chloride of ammonium in the imperial gallon, 

 or 2 5 '20 grains of ammonia ; or 1000 grains of this solution 

 contained 1*14 grains of chloride of ammonium, or *36 grains of 

 ammonia. 



The soils experimented upon were the same as those used in 

 the First Series of Experiments, namely : 



1. A calcareous clay. 



2. A fertile loam. 



3. Stiff clay soil. 



4. Sterile sandy soil. 



5. Pasture land. 



In each case 3500 grains of soil were mixed with 14,000 grains 

 of a solution of chloride of ammonium, containing *36 grains of 

 ammonia in 1000 grains of liquid. After standing three days 

 the clear liquid was drawn off, and the ammonia contained in it 

 obtained by distillation with caustic potash. The operation was 

 conducted in each case alike, and the following results were 



Obtained : Ammonia. 



Grains. 



No. 1. 1000 grains of soil absorbed .. '68 



No. 2. ,, ,, .. .. -76 



No. 3. ,, ,, .. .. -80 



No. 4. ,, ,, .. .. -16 



No. 5. ,, ,, .. .. -64 



D 



