On the Chemical Properties of Soils. 15 



which I have published some filtration experiments in Part I., 

 vol. xx. of this Journal. For the latter experiments I used liquid 

 manure, which, in addition to a great number of chemical fer- 

 tilizing matters, contained only 3'36 grains of ammonia in the 

 imperial gallon. It might certainly have been expected that 

 20,000 grains of soil would have absorbed this small quantity 

 of ammonia, the absorption even then being only at the rate of 

 *168 grains of ammonia to 1000 grains of soil. Notwithstanding 

 the large quantity of clay in Mr. Mechi's soil, and the small 

 quantity of ammonia in his liquid manure, only 1*81 grains of 

 ammonia were absorbed by 20,000 grains of soil, and 1*55 grains 

 remained in the liquid after three days' contact with it. In this 

 experiment 1000 grains of soil thus absorbed only "0905 of a 

 grain of ammonia. 



In my remarks on this experiment, I express the opinion that 

 a stronger solution of ammonia passed through Mr. Mechi's soil 

 would have parted with a much larger proportion of ammonia 

 than in this experiment. The proof of this is now given. In 

 the former experiment 1000 grains of this clay soil removed only 

 0905 of a grain of ammonia from a very dilute ammoniacal 

 liquid ; in the present experiment the same quantity of the 

 same soil absorbed about eight times as much, or *754 grains 

 of ammonia from the stronger solution, containing 23*24 grains 

 of ammonia per gallon. 



It must, however, be remembered, that whereas I employed in 

 my former experiments highly complex liquids, in my present 

 trials simple solutions of caustic ammonia were used. The 

 quantity of ammonia which a soil is capable of absorbing must 

 no doubt depend in some degree on the conditions under which 

 the ammonia is present in the liquid. The preceding experiment 

 is, therefore, not quite conclusive. In order to satisfy myself 

 beyond doubt whether more ammonia is really removed from a 

 stronger than from a weaker solution or not, I instituted a second 

 series of experiments, which I must briefly describe. 



SECOND SERIES OF ABSORPTION EXPERIMENTS WITH STRONGER 

 AMMONIA SOLUTIONS. 



A solution of ammonia in distilled water was prepared, con- 

 taining about twice as much ammonia as that used in the first 

 series. To speak more exactly, this stronger solution contained 

 47-11 grains of ammonia per gallon, or '673 grains of ammonia in 

 1000 grains of liquid. 



The clear ammoniacal solution having been poured off the soil 

 as completely as was possible in each of the five experiments of 

 the first series, the liquid remaining with the soils in the bottles 



