120 OF THE INORGANIC CONSTITUENTS OF PLANTS. 



of potash, although very little nitrogen. All the 

 potash, in fact, which is contained in the food con- 

 sumed by a cow is again immediately discharged in 

 its excrements. 



The experience of a proprietor of land in the 

 vicinity of Gottingen offers a most remarkable ex- 

 ample of the incapability of a soil to produce wheat 

 or grasses in general, when it fails in any one of 

 the materials necessary to their growth. In order 

 to obtain potash, he planted his whole land with 

 wormwood, the ashes of which are well known to 

 contain a large proportion of the carbonate of that 

 alkali. The consequence was, that he rendered his 

 land quite incapable of bearing grain for many years, 

 in consequence of having entirely deprived the soil 

 of its potash. 



The leaves and small branches of trees contain 

 the most potash ; and the quantity of them which is 

 annually taken from a wood, for the purpose of 

 being employed as litter,* contains more of that alkali 

 than all the old wood which is cut down. The bark 

 and foliage of oaks, for example, contain from 6 to 

 9 per cent, of this alkali; the needles of firs and 

 pines, 8 per cent. 



With every 2920 lbs. of firwood which are yearly 

 removed from an acre of forest, only from 0*125 to 

 0'58 lbs. of alkalies are abstracted from the soil, 

 calculating the ashes at 0*83 per cent. The moss, 

 however, which covers the ground, and of which the 

 ashes are known to contain so much alkali, con- 

 tinues uninterrupted in its growth, and retains that 

 potash on the surface, which would otherwise so 

 easily penetrate with the rain through the sandy 

 soil. By its decay, an abundant provision of alkalies 



* This refers to a custom some time since very prevalent in Ger- 

 many, although now discontinued. The leaves and small twigs of 

 trees were gleaned from the forests by poor people, for the purpose 

 of being used as litter for their cattle. The trees, however, were 

 found to suffer so much in consequence, that their removal is now 

 strictly prohibited. The cause of the injury was that stated in the 

 text. — Ed.] 



