THE ASH OF PLANTS. 173 



Ripe Fruit. 



Stamens. Peta.lt. Green Fruit. Kernel. Green Brown 



Shell. Shell. 



Potash 60.7 61.2 58.7 61.7 75.9 54.6 



Lime 13.8 13.6 9.8 11.5 8.6 16.4 



Magnesia 3.1 3.8 2.4 0.6 1.1 2.4 



Sulphuric acid trace trace 3.7 1.7 1.0 3.6 



Phosphoric acid... 19.5 17.0 20.8 22.8 5.3 18.6 



Silica 0.7 1.5 0.9 0.2 0.6 0.8 



Chlorine 2.8 3-8 4.8 2.0 7.6 5.2 



4. Similar kinds of plants, and especially the same parts 

 of similar plants, exhibit a close general agreement in the 

 composition of their ashes ; while plants which are un- 

 like in their botanical characters are also unlike in the 

 proportions of their fixed ingredients. 



The three plants, wheat, rye, and maize, belong, botan- 

 ically speaking, to the same natural order, graminece, and 

 the ripe kernels yield ashes almost identical in composi- 

 tion. Barley and the oat are also graminaceous plants, 

 and their seeds should give ashes of similar composition. 

 That such is not the case is chiefly due to the fact, that, 

 unlike the wheat, rye, and maize-kernel, the grains of 

 barley and oats are closely invested with a husk, which 

 forms a part of the kernel as ordinarily seen. This husk 

 yields an ash which is rich in silica, and we can only prop- 

 erly compare barley and oats with wheat and rye, when 

 the former are hulled, or the ash of the hulls is taken out 

 of the account. There are varieties of both oats and bar- 

 ley, whose husks separate from the kernel the so-called 

 naked or skinless oats and naked or skinless barley and 

 the ashes of these grains agree quite nearly in composi- 

 tion with those of wheat, rye, and maize, as may be seen 

 from the table on page 174. 



By reference to the table (p. 166), it will be observed 

 that the pea and bean kernel, together with the allied 

 vetch and lentil (p. 171), also nearly agree in ash-com- 

 position. 



So, too, the ashes of the root-crops, turnips, carrots, 



