COMPOSITION OF WHEAT 39 



eight per cent of water in wheat in a room in which the moist 

 air of New Haven circulated in September and in Februar}' 

 when the room was heated by a furnace. Richardson, found 

 that two days were sufficient to equalize the moisture in samples 

 of flour which originally varied from less than eight to over 

 thirteen per cent. Afterward the water in the samples fluctu- 

 ated with the humidity of the air. 



68. Ash. — Lawes and Gilbert give the average composition 

 of the ash of the grain and straw of wheat on an unmanured 

 plat during twenty years as follows : ^ 



Grain Straw 



Fifty per cent more phosphoric acid than potash is laid up 

 in the grain, while in the straw five times as much potash as 

 phosphoric acid is accumulated. A relatively large amount of 

 magnesia is stored in the grain, while relatively more lime is to 

 be found in the straw. More than two-thirds of the ash of straw 

 is silica. Formerly it was held that the silica helped to stiffen 

 the straw. This view is no longer held, since the accumulation 

 of silica is greater in the upper portion of the stem. 



It has been shown that the ash constituents of normally 

 ripened seeds of wheat are remarkably uniform, but va.ry some 



I Jour. Am. Chem. S v:. Vol XLV (188S), p. 100. 



