28 On the Chemical Properties of Soils. 



It wil be noticed that the proportions of ammonia which are 

 absorbed by the five different soils from a solution of sal- 

 ammoniac, containing 79*80 grains of this salt in an imperial 

 gallon, vary considerably. 



In the case of the sandy soil very little ammonia indeed was 

 absorbed, This is rather singular, since the same sandy soil 

 absorbed a good deal of ammonia on being brought into contact 

 with a dilute solution of free ammonia. 



We thus see that a soil may absorb free ammonia in consider- 

 able quantities, and yet not have the power of separating and 

 fixing ammonia from an ammoniacal salt, such as sal-ammoniac. 



SEVENTH SERIES. ABSORPTION OF AMMONIA FROM A SOLUTION 

 OF SULPHATE OF AMMONIA. 



A solution of sulphate of ammonia was prepared, containing 

 77*70 grains of sulphate of ammonia per imperial gallon, or 20*16 

 grains of ammonia. 1000 grains of liquid therefore contained 

 *288 grains of ammonia. The same soil was used in this as in 

 the preceding Series of Experiments. In each case 3500 grains 

 of soil were shaken up in a well-stoppered bottle with 14,000 

 grains of the solution of the above strength. In these experi- 

 ments Ammonia. 



Grains. 



No. 1. 1000 grains of soil absorbed .. .. -608 



No. 2. ,, ,, .. .. -640 



No. 3. ,, ,, .. .. -576 



No. 4. ,, ,, .. .. -256 



No. 5. ,, ,, .... -448 



Here again the sandy soil absorbed but very little ammonia. 

 There seems thus to be something or other wanting in this 

 soil which prevents it from exercising a decomposing influence 

 upon ammoniacal salts similar to that manifested by the four 

 other soils. I am informed that farmyard manure, guano, and 

 other fertilizers of recognized value, produce little effect upon the 

 crops growing on this sterile sandy soil. 



EIGHTH SERIES. RETENTION OF AMMONIA FROM A SOLUTION 

 OF SULPHATE OF AMMONIA. 



In the Fifth Series of experiments I have shown that a soil 

 which absorbed a certain quantity of free ammonia from a 

 tolerably strong solution with which it was brought into contact, 

 again yielded small quantities of ammonia to repeated washings 

 of distilled water. 



It appeared to me desirable to ascertain whether similar 

 results would be obtained on washing a soil which had absorbed 

 a certain quantity of ammonia from a solution of sulphate of 

 ammonia. 



