is a characteristic
constituent.

This 'furfuroid' while equally resistant to alkalis as the normal
cellulose group with which it is associated, is selectively hydrolysed
by acids. Thus straw cellulose dissolves in sulphuric acids of
concentration H_{2}SO_{4}.2H_{2}O - H_{2}SO_{4}.3H_{2}O, and on diluting
the normal cellulose is precipitated as a hydrate, and the furfuroid
remains in solution. But this sharp separation is difficult to control
in mass. By heating with a very dilute acid (1 p.ct. H_{2}SO_{4}) the
conditions are more easily controlled, the most satisfactory results
being obtained with 15 mins. heating at 3 atm. pressure.

(1) Operating in this way upon brewers' grains the furfuroid was
obtainable as the chief constituent of a solution for which the
following experimental numbers were determined:--Total dissolved solids,
28.0 p.ct. of original 'grains'; furfural, 39.5 p.ct. of total dissolved
solids, as compared with 12.5 p.ct. of total original grains; cupric
reduction (calc. to total solids), 110 (dextrose = 100) osazone; yield
in 3 p.ct. solution, 35 p.ct. of weight of total solids.

Pentosazone
Analysis N 17.1 17.3 17.07
C 62.5 62.3 62.2
H 6.4 6.5 6.1
Melting-point 146 deg.-153 deg.

From these numbers it is seen that of the total furfuroids of the
original 'grains' 84 p.ct. are thus obtained in solution in the fully
hydrolysed form, which is that of a pentose or pentose derivative. It
was, however, found impossible to obtain any crystallisation from the
neutralised (BaCO_{3}) and concentrated solution, the syrup being kept
for some weeks in a desiccator. It was noted at the same time that the
colour reaction of the original solution with phloroglucol and
hydrochloric acid was a deep violet, in contradistinction to the
characteristic red of the pentoses. On oxidation with hydrogen peroxide,
in the proportion of 1 mol. H_{2}O_{2} to 1 mol. of the carbohydrate in
solution, carbonic anhydride was formed in quantity = 20.0 p.ct. of the
latter.

Fermentation (yeast) experiments also showed a divergence from the
resistant behaviour of the pentoses, a considerable proportion of the
furfuroid disappearing in a normal fermentation.

(2) The quantitative methods above described were employed in
investigating the barley plant at different stages of its growth. The
green plant was ext