Analyses of Ashes of Plants. 
665 
Twenty-eight bushels has been shown to be the mean crop per 
acre of the specimens we have examined, and \'%7 per cent, the 
amount of ash. 
If we collect, on the one hand, all those specimens which exceed, 
and, on the other, those which fall short of this per centage, taking 
the mean of their quantities and of the per centage of ash, we 
shall obtain the following result : — 
The mean of specimens affording less than 1-67 per cent, of 
ash, is 
30 bushels of grain to the acre, 
And 1 • 56 per cent, of ash. 
Of those affording more than 1*67 per cent, of ash, the mean is 
27 bushels of grain to the acre, 
And 1 '76 per cent, of ash. 
Now 
Bushels. Ash. ^Bushels. Ash.' 
As 30 : l-ie :: 27 : 1-58; 
very nearly the amount which our results indicate. 
The quantity of ash then would appear to be inversely as the 
crop — that is, the quantity of mineral matter does not increase 
with the amount of crop, but is less in proportion to the vegetable 
matter in the large than in the smaller produce. This would 
seem to lead to the inference that the quantity of mineral matter 
present in plants is to a certain extent regulated by the abund- 
ance of the supply. 
But whilst we point this out as a circumstance worthy of consi- 
deration, we repeat that neither variety, soil, climate, manure, nor 
' quantity of crop, will satisfactorily account for the deviations 
which occur in the quantity of ash in the grain of wheat. Beforej 
however, we proceed further in this inquiry, it will be best to con- 
sider the composition of the ash. 
Of the chemical composition of the ash of wheat grain : — We 
have before mentioned the substances of which the ashes of plants 
in general are composed. The following table shows the amount 
of each of them in 26 specimens of the ash of wheat : — 
