ence to a definitely ketonic formula,
for which, moreover, some farther grounds remain to be mentioned. In the
systematic investigation of the nitric esters of the carbohydrates (p.
41) Will and Lenze have definitely differentiated the ketoses from the
aldoses, as showing an internal condensation accompanying the ester
reaction. Not only are the OH groups taking part in the latter
consequently less by two than in the corresponding aldoses, but the
nitrates show a much increased stability. This would give a simple
explanation of the well-known facts obtaining in the corresponding
esters of the normal cellulose. We may note here that an important item
in the quantitative factors of the cellulose nitric ester reaction has
been overlooked: that is, the yield calculated to the NO_{3} groups
fixed. The theoretical yields for the higher nitrates are

Yield p.ct. N p.ct.
of cellulose of nitrate
Pentanitrate 169 12.7
Hexanitrate 183 14.1

From such statistics as are recorded the yields are not in accordance
with the above. There is a sensible deficiency. Thus Will and Lenze
record a yield of 170 p.ct. for a product with 13.8 p.ct. N, indicating
a deficiency of about 10 p.ct. As the by-products soluble in the acid
mixture are extremely small, the deficiency represents approximately the
water split off by an internal reaction. In this important point the
celluloses behave as ketoses.

In the lignocelluloses the condensed constituents of the complex are of
well-marked ketonic, i.e. quinonic, type. In 'nitrating' the
lignocelluloses this phenomenon of internal condensation is much more
pronounced (see p. 131). As the reaction is mainly confined to the
cellulose of the fibre, we have this additional evidence that the
typical carbonyl is of ketonic function. It is still an open question
whether the cellulose constituents of the lignocelluloses are
progressively condensed--with progress of 'lignification'--to the
unsaturated or lignone groups. There is much in favour of this view,
the evidence being dealt with in the first edition, p. 180. The
transition from a cellulose-ketone to the lignone-ketone involves a
simple condensation without rearrangement; from which we may argue back
to the greater probability of the ketonic structure of the cellulose. We
must note, however, that the celluloses of the lignocelluloses are
obtained as residues of various