G70 
Analyses of Ashes of Plants. 
examining' the proportion of phosphoric acid and potash in the 5 
specimens of Hopeton wlieat in the table in this page, (Specs. 38, 
39,40,41,42). On the other hand, the character of the soil 
does not much affect the composition of the ash — that is to say, 
the predominance of any particular substance in the soil does not 
cause it to be present in greater amount in the ash. In speci- 
men 48, for instance, grown on the magnesian limestone, the 
quantity of magnesia is very liltle above the average, and by no 
means so great as in several other specimens. The ash ofsamples 
of wheat from the chalk does not contain more lime than when 
the wheat has been the produce of a clay or a sand. By reference 
to the table, however, we shall see that the samples grown upon 
ciay give upon the whole more phosphoric acid than those from 
sands or light calcareous soils ; but the connection either in quan- 
tity or composition of the ash with the mineral circumstances of the 
growth of the crop, is not by any means satisfactory or so uniform 
as might have been expected. In making up our results, we have 
been strongly impressed with the wish to discover the cause of this 
want of correspondence, and we believe we have obtained a clue to it. 
The crrain of wheat is not homogeneous, consistinor of two me- 
c'.ianically distinct parts — the skin or bran, and the flour ; and tliese 
two, again, are not themselves elementary vegetable principles : the 
flour contains starch and gluten, sugar and gum : the bran, Avoody 
fibre and nitrogenized bodies allied to gluten. Now it is quite 
possible that each one of these bodies has an ash peculiar to itself 
both in quantity and composition ; and according!}', as tiiey exist 
to a greater or less extent in the grain, so will its mineral compo- 
sition differ. As the bran contains more mineral matter than the 
flovu', a thick-skinned wheat will give a greater quantity of ash 
than one having less bran. And again, if gluten and starcli have a 
different mineral constitution, the flour of two wheats will be in- 
fluenced in respect to its ash by the relative proportion of gluten 
and starch which it contains. We have made an examination of 
one or two spscimens, which, although it by no means clears up 
the difficulty, gives great promise of leading to some general 
principle in regard to the ashes of plants. Tlie following table 
shows the connection existing between the vegetable and mineral 
constituents of 4 specimens of wheat : — 
1 0.11) 
Whole Ua.MX. 
Fi.oini. 
luten. 
t2 
< 
eft 
a 
O 
o 
Variety. 
Sail. 
O 
a 
"3 
St 
a. 
j: 
c 
e 
6 
y. 
■71 
< 
!S 
< 
if 
Glut 
< 
Phoi 
Pota 
CS 
38 
Ilopetoa 
Gritly siliceous sand 
~ 
1 -ci 
1 1 ■ j(i 
)•-« 
Wi\ 
11-40 
0-226 
39-97 
41 -j,') 
13-20 
Ml 
Ditto 
StilTclay . 
1 •.■)8-i 
1 -(i:! 12 00 
11-02 
0-238 47-,tH 
33 • 43 
9-32 
40 
Ditto 
Sandy . 
1 -lior. 
I'-l 
l'i-0(l 
)•■;.') 
1 :> ■ III 
11 •.19 
0-210 43-118 
3IJ-3H 
1 1 -69 
■11 
Ditto 
Clay . 
1 -SOS 
1 TiO 12-0(' 
)-'.l2 12-0( 
Il-il.n') 0-2-I8 <9'2'.' 
' 1 
30-39 
12-38 
