84 POTASH. 



ash, and the carbon of the potash unites with 

 the lime, thus forming carbonate of lime and 

 nitrate of potash. 



In this case it may appear that, although 

 little or no potash might be present, still that 

 all the nitrogen would be absorbed by the lime, 

 and hence it might be inferred, that as far as 

 the agriculturist was concerned that no loss 

 would accrue to him ; but this is a dangerous 

 doctrine, it is not only a necessary condition 

 that a certain substance should be present in a 

 soil to become the nutriment of the plant ; but 

 it is also necessary that it should be present 

 there in that state in which it most readily fur- 

 nishes such nutriment, and in the present case, 

 with the knowledge already possessed, there is 

 no doubt but that the nitrate of potash is a 

 more efficient manure than the nitrate of lime. 



Potash is, as we have previously noticed, 

 never met with in its free state, but always in 

 combination with some acid or gas. Thus it 

 has been explained that the potash contained in 

 wood ashes is a carbonate of potash, whilst 

 that in the soil is a nitrate of potash, and it 

 exists in an impure state, in a variety of com- 

 binations, but the two just specified are those 

 most frequently and commonly met with. In 

 its ultimate analysis nitrate of potash, is an 

 oxide of the metal potassum combined with ni- 

 trogen, and the carbonate of potash is an oxide 

 of the same metal united to carbon. This is 

 not exactly the way in which it would be che- 

 mically expressed, but it is sufficiently clear 

 and distinct for the purpose here required. 



In whatever state it may exist in the soil, its 



