Anahjses of Ashes of Plants. 
661 
There is no very evident connection between the quantity of ash 
and the soil upon which the specimen has grown ; but if we may 
judge from the mean of the instances in the tables, it would ap- 
pear tliat straw from clays contains the most ash — that i'rom cal- 
careous soils containing less, but more than the produce of sandy 
(silicious) soils. 
The variety of wheat would seem to control the proportion of 
ash of the straw ; and the relative strength of different specimens 
is certainly to some extent dependent upon its amount. Thus in 
Piper's thickset (Spec. 32), which possesses a straw of unusual 
strength, the proportion of ash is very great, more than doubling 
the usual average. This peculiarity is not observable in another 
s pecimen of straw of the same wheat (Spec. No. 8) ; but we have 
already remarked the singular lovvness of ash in this instance as 
due in some way to the soil. 
The mean of 40 specimens of straw given in the table will be 
found to be 4*50, or about 100 lbs. of ash for every ton of straw. 
The greatest quantity of ash removed from an acre by the straw 
of any crop which we have examined is 243 lbs. (Spec. 47) ; in 
this case the per centage of ash is very high. The amount of 
mineral matter removed from the soil by the straw will of course be 
dependent on the quantity of straw itself, and therefore on the season. 
The proportion of ash in the chaff varies between the limits of 
7 and 16 per cent. ; more frequently, however, being found be- 
tween 12 and 15 per cent. ; as in the case of the straw, the sili- 
cious soils give chaff containing the least ash, and clays the most, 
the calcareous soils being intermediate in this respect. The ash 
in the chaff, indeed, in many instances corresponds with that of the 
straw. Thus in specimens 1, 2, 3, 4, 6, 11, we have a very low 
per centage of ash both in the straw and cliaff ; and this might be 
expected, as the chaff is only a prolongation of the straw. The 
40 specimens of chaff give a mean ash of 12*25 per cent. ; so that 
one-eighth part of the chaff of wheat is mineral matter. 
We have already shown that chaff contains on an average 
12-25 per cent, of water. No less than one-fourth, then, of its 
whole weight consists of matter incapable of affording nourishment 
to animals ; this should be taken into account in estimating the 
feeding properties of wheat-chaff. Every ton of it being equi- 
valent to 15 cwt. only of solid vegetable food. 
According to the calculation just given, a ton of chaff would 
contain 274 lbs. (about 2^ cwt.) of mineral matter. The largest 
amount removed from an acre by the chaff in any of the crops 
described, is seen in Specimens 32 and 33, where it reaches 85 lbs. 
Of the ash in the grain : — 
By the table (page 660) it will be seen that the quantity of ash 
for a given weight of grain is not by any means constant, though 
