he
ash principally in combination with that base as common salt. The
relation between these two elements may be traced more or less
distinctly throughout the whole table of analyses, and conspicuously in
that of mangold-wurzel, where the common salt amounts to almost exactly
one-half of the whole mineral matter. The analyses of the cultivated and
uncultivated asparagus also show that a diminution in the soda is
accompanied by a reduction in the proportion of chlorine.

_Sulphuric Acid_ is an essential constituent of the ash. But it is to be
observed that it is in some instances entirely, and in all partially, a
product of the combustion to which the plant has been submitted in order
to obtain the ash. It is partly derived from the sulphur contained in
the albuminous compounds, which is oxidised and converted into sulphuric
acid during the process of burning the organic matter, and remains in
the ash. The quantity of sulphuric acid found in the ash is, however, no
criterion of that existing in the plant, for a considerable quantity of
it escapes during burning. The extent to which this occurs in particular
instances is well illustrated by reference to the case of white mustard,
which yields an ash containing only 2.19 of sulphuric acid, equivalent
to 0.9 of sulphur; and if calculated on the seed itself, this will
amount to no more than 0.039 per cent, while experiments made in another
manner prove it to contain about thirty times as much, or more than 1
per cent. For the purpose of determining the total quantity of sulphur
which the plants contain in their natural state, it is necessary to
oxidise them by means of nitric acid; and from such experiments the
following table, showing the _total_ amount of sulphur contained in 100
parts of different plants, dried at 212 deg., has been constructed:--

Poa palustris 0.165
Lolium perenne 0.310
Italian Ryegrass 0.329
Trifolium pratense 0.107
repens 0.099
Lucerne 0.336
Vetch 0.178
Potato tuber 0.082
tops 0.206
Carrot, root 0.092
tops 0.745
Mangold-Wurzel, root 0.058
tops 0.502
Swede, root 0.435
tops 0.458
Rape 0.448

Drumhead Cabbage 0.431
Wheat, grain 0.068
straw 0.2