n a 500-cc. flask add 200 cc. of boiling
1.25-percent sulphuric acid; connect the flask with a reflux condenser,
the tube of which passes only a short distance beyond the rubber stopper
into the flask, or simply cover a tall conical flask, which is well
suited for this determination, with a watch glass or short stemmed
funnel. Boil at once and continue boiling gently for thirty minutes. A
blast of air conducted into the flask may serve to reduce the frothing
of the liquid. Filter through linen, and wash with boiling water until
the washings are no longer acid; rinse the substance back into the flask
with 200 cc. of the boiling 1.25-percent solution of sodium hydroxid
free, or nearly so, of sodium carbonate; boil at once and continue
boiling gently for thirty minutes in the same manner as directed above
for the treatment with acid. Filter at once rapidly, wash with boiling
water until the washings are neutral. The last filtration may be
performed upon a Gooch crucible, a linen filter, or a tared filter
paper. If a linen filter is used, rinse the crude fiber, after washing
is completed, into a flat-bottomed platinum dish by means of a jet of
water; evaporate to dryness on a steam bath, dry to constant weight at
110 deg. C., weigh, incinerate completely, and weigh again. The loss in
weight is considered to be crude fiber. If a tared filter paper is used,
weigh in a weighing bottle. In any case, the crude fiber after drying to
constant weight at 110 deg. C., must be incinerated and the amount of the
ash deducted from the original weight.

17. _Starch--Tentative_

Extract 5 grams of the finely pulverized sample on a hardened filter
with five successive portions (10 cc. each) of ether, wash with small
portions of 95-percent alcohol by volume until a total of 200 cc. have
passed through, place the residue in a beaker with 50 cc. of water,
immerse the beaker in boiling water and stir constantly for 15 minutes
or until all the starch is gelatinized; cool to 55 deg. C., add 20 cc. of
malt extract and maintain at this temperature for an hour. Heat again to
boiling for a few minutes, cool to 55 deg. C., add 20 cc. of malt extract
and maintain at this temperature for an hour or until the residue
treated with iodin shows no blue color upon microscopic examination.
Cool, make up directly to 250 cc., and filter. Place 200 cc. of the
filtrate in a flask with 20 cc. of hydrochloric acid (sp. gr. 1.125);
connect with a reflux condenser a