THE ASH OF PLANTS. 163 



ysed the ashes of several plants, cultivated in a poor soil, 

 with the addition of various mineral fertilizers. The in- 

 fluence of the added substances on the composition of the 

 plant is very striking. The following figures comprise 

 his results on the ash of buckwheat straw, which grew on 

 the unmanured soil, and on the same, after application of 

 the substances specified below : 



100.0 100.0 100.0 100.0 100.0 100.0 



It is seen from these figures that all the applications 

 employed in this experiment exerted a manifest influence, 

 and, in general, the substance added, or at least one of its 

 ingredients, is found in the plant in increased quantity. 



In 2, chlorine, but not sodium ; in 3 and 4, potash j in 

 5, sulphuric acid and magnesia, and in 6, lime, are present 

 in larger proportion than in the ash from the unmanured 

 soil. 



6* What is the JSTormal Composition of the Ash of a 

 Plant f It is evident from the foregoing facts and consid- 

 erations that to pronounce upon the normal composition 

 of the ash of a plant, or, in other words, to ascertain what 

 ash-ingredients and what proportions of them are proper 

 to any species of plant or to any of its parts, is a matter 

 of much difficulty and uncertainty. 



The best that can be done is to adopt the average of a 

 great number of trustworthy analyses as the approximate 

 expression of ash-composition. From such data, however, 

 v/c are still unable to decide what are the absolutely es- 



