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EXPEBIMENTS ON THE COMPOSITION OF WHEAT GRAIN. 
BY A. H. CHURCH, M.A. OXON., Y.C.S., 
Professor of Chemistry in the Royal Agricultural College , Cirencester. 
The influence of season, climate, manure, etc., upon the composition of wheat grain,, 
has engaged the attention of many scientific observers. MM. Boussingault, J. Pierre, 
and Reiset, abroad, and Messrs. Lawes and Gilbert, in this country, have added several 
important facts to our knowledge of the variations in the yield and quantity of corn 
under different conditions of culture and atmospheric influence, and also according to 
the particular variety of seed grown. There were still several points to be cleared up, 
and it is to one among these that my attention has been more particularly directed since 
the autumn of 1863. It is the relation of the density of the seed to its chemical compo¬ 
sition, and to its germinating and productive powers, that I have submitted to an expe¬ 
rimental investigation. The first portion of my results has been already published,* and 
a brief account of those more recently obtained may prove of interest to the readers 
of the ‘Journal of Botany.’ 
Most samples of dressed wheat-grain, if carefully examined, will be found to consist 
partly of hard, horny, subtranslucent grains, partly of softer opaque floury grains, and 
partly of grains presenting a mixed aspect. I have specially examined two varieties of 
wheat, and the proportions of the three sorts of grain which my samples contain are 
given here in percentages:— 
Spalding red wheat (1864). 
Translucent . . . . 49 per cent. 
Medium.34 „ 
Opaque.17 „ 
Hallett’s white rough 
chaffed (1865). 
24 per cent. 
31 
45 
These proportions fluctuate, however, even with the same variety of wheat under the 
various conditions of season, maturity, when cut, etc. It is not, however, these propor¬ 
tions that I wish to discuss, but a remarkable difference in composition between the trans¬ 
lucent and the opaque grains. I am aware that previous observers have detected cer¬ 
tain chemical differences between the poor shrivelled grains and the full plump grains. 
But the grains which I find to offer a most striking contrast as to the proportions of 
their most important constituent, present no striking contrast in size, shape, or weight. 
In Hallett’s white wheat, for instance, the 24 translucent grains weigh 19 grs.; the 45 
opaque grains weigh 34-2 grs. Had the opaque grains been of exactly the same den¬ 
sity and size as the translucent grains, their weight would have been 35-6 grs. instead 
34-2—a very trifling difference, due not only to a difference in the size of the two sorts 
of seed, but to a slight difference in density in favour of the translucent grains. This 
difference in density is brought out very plainly when the seed is placed in a strong 
solution of chloride of calcium under the air-pump. With the solution of specific 
gravity, 1-247, 71 per cent, of the grains sink, 29 per cent, float. In 100 of the heavy 
grains thus separated there are generally 35 to 38 translucent grains, and only 18 opaque; 
while in 100 of the light grains thus separated, there are usually only 10 translucent 
grains, and as many as 70 opaque grains. With these observations on one physical dis¬ 
tinction of importance between the two sorts of seed, I may introduce my experiments 
on their chemical differences. 
The amount of water in the selected seeds was practically the same :— 
Percentage of Water. 
Spalding red. Hallett’s white. 
Translucent.16-12.14 - 34 
Opaque.16-10. -47 
But the percentages of nitrogen were remarkably different:— 
* ‘ Practice with Science,’ part i. p. 101. Longman, 1865. 
YOL. VII. 
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