by boiling with a dilute acid (1.25
p.ct. H_{2}SO_{4}), which treatment may be carried out on the raw
material--i.e. before exposure to the acid chlorate, or on the crude
cellulose as ordinarily isolated.

~Determination of Tissue-constituents.~--By the regulated action of
certain solvents applied in succession, it appears that such
constituents of the plant-complex can be removed as have no organic
connection with the cellular skeleton: the residue from such treatments,
conversely, fairly represents the true tissue-constituents. The author
employs the method of digestion with cold dilute alkaline solutions
(0.15 to 0.5 p.ct. NaOH), followed by exhaustive washing with cold and
hot water, afterwards with cold and hot alcohol, and finally with ether.

The residue is dried and weighed as crude product. When necessary, the
proportions of ash and proteid constituents are determined and deducted
from the 'crude product' which, thus corrected, may be taken as
representing the 'carbohydrate' tissue constituents.

~Determination of Hemicelluloses.~--By the process of boiling with dilute
acids (1.25 p.ct. H_{2}SO_{4}) the hemicelluloses are attacked--i.e.
hydrolysed and dissolved. The action of the acid though selective is, of
course, not exclusively confined to these colloidal carbohydrates. The
proteid and mineral constituents are attacked more or less, and the
celluloses themselves are not entirely resistant to the action. The loss
due to the latter may be neglected, but in calculating the hemicellulose
constants from the gross loss the proteids and mineral constituents
require to be taken into account in the usual way.

QUANTITATIVE SEPARATION OF HEMICELLULOSE, CELLULOSE, AND LIGNIN.
PRESENCE OF PENTOSANES IN THESE SUBSTANCES.

WILHELM HOFFMEISTER (Landw. Versuchs-Stat, 1898, 50, 347-362).

(p. 88) The separation of the cellulose-like carbohydrates of sunflower
husks is described.

In order to ascertain the effect of dilute ammonia on the cellulose
substances of lignin, a dried 5 p.ct. caustic soda extract was extracted
successively with 1, 2, 3, and 4 p.ct. sodium hydroxide solution. Five
grams of the 2 p.ct. extract were then subjected to the action of
ammonia vapour; the cellulose did not completely dissolve in six weeks.
Cellulose insoluble in caustic soda (32 grms.) was next extracted with
ammonia, in a similar manner, for 10 days, dried, and weighed. 30.46
grms. remained, which, when treated with 5 p.ct. aqueo