WATER IN AGRICULTURE. 181 



even this delicate test fails to give any signs of its 

 presence in soils upon which the beet root flour- 

 ishes. The growth of the root demands it, and 

 water by some subtle instinct hunts it from the soil 

 and supplies it in the needed quantity. Tobacco is 

 one of the most extraordinary plants which spring 

 from the soil. In its ash is found a class of rare 

 and complex bodies which it has abstracted there- 

 from, and which are not found in any other veg- 

 etable structure. Also, it is a great plunderer of 

 the soil, in respect to those substances which are 

 supplied to it through the ordinary fertilizing agents. 

 The amount of mineral constituents which it carries 

 off can be judged of by carefully examining the 

 ash upon the end of a smoker's cigar. Every 100 

 Ibs. of the dried leaves which the soil produces rob 

 it of at least twenty pounds of its most valuable 

 mineral atoms. This vast amount of mineral the 

 plant pumps vip, while held in solution by water. 

 To this plant, potash is what pie or cake is to the 

 schoolboy ; it evidently loves it, and consumes it 

 in prodigious quantities. Five per cent, of the 

 dried leaves are composed of this alkali. A bushel 

 of ashes, such as the smoker so carelessly and 

 wastefully brushes from the end of his cigar, would, 

 if leached and the lye formed into soap, make 

 enough to answer the purpose of a small family for 

 a year. The new and rare element, lithium, is 



