Objects to be Accomplished by Plowing. 141 



as before. This was repeated seven times successively, with the 

 following results: 



First washing, removed by 7,000 grains of water . 



Second " 



Third " 



Fourth " 



Fifth 



Sixth " 



Seventh " 



Total.... 2.651 " 



Thus we see that after seven successive washings with 7,000 

 grains of water, or 49,000 grains of water in all, only 2.651 grains 

 of ammonia was obtained from a quarter of a pound of soil. It 

 had previously absorbed 4.655 grains of ammonia, and there were 

 therefore 2.004 grains left in it after this very thorough washing. 



It is very clear from this experiment that the power of soils 

 to remove ammonia from solutions is much greater than their 

 property of yielding it again to water. 



Prof. Way discovered that soils not only possessed the power 

 of separating ammonia, but likewise other bases from their solu- 

 tions, and they held them after being so absorbed Avith very great 

 tenacity. Thus, 100 grains of clay soil taken from the plastic 

 clay formation in England absorbed 1.050 grains of potash from 

 a solution of caustic potash containing one per cent of the alkali. 

 It is interesting to observe that the liquid was not in this case 

 filtered through the soil, but only left in contact with the cold 

 solution for twelve hours. 



Prof. Way has further shown that soils have the ability to 

 separate the alkaline bases from the acids with which they arc 

 combined. He found that when saline solutions were slowly 

 filtered through soils five or six inches deep, the liquids which 

 passed through were deprived of their alkaline bases, as potash, 

 soda, ammonia and magnesia, and only the acids were to be found 

 in combination with some other base. Thus when muriate of 

 ammonia was filtered through the soil the ammonia was removed, 

 and a corresponding quantity of lime in combination with muri- 

 atic acid was found in the filtered liquid. In the same way 

 sulphate of potash was deprived of its base, and the liquid col- 

 lected gave sulphate of lime on analysis. 



Prof. Liebig has attempted to show that this power of soils 

 which enables them thus to attract manurial substances from their 



