Alcohol extract is made in the same manner as the ether extract, using,
of course, the substance extracted. The solvent may be either absolute
alcohol—that of 95 per cent. by volume, or 80 per cent. by weight, the
latter being preferable in most cases, as there is no definite point
with the stronger spirit at which the extraction is completed.
The amount of reducing material produced by boiling the spices with
dilute acids serves with several as an index of purity. In the case of
pepper, which contains a large amount of starch, the addition of fibrous
adulterants reduces the equivalent of reducing sugar, which are
indicated in the solution after boiling with acid. Tumeric is always
found in spices, such as cloves and pimento of good quality.
It has been said that preliminary extractions of the material with the
best ether is necessary to remove oil and other substances, not tannin
on which permanganate may act; ordinary ether will not answer, as it
contains so much alcohol and water as to dissolve some of the tannin.
The substance freed from ether should be extracted with boiling water
and the extract made up to such dilution that 10 CC. is equal to about
10 CC. of the thirtieth normal,—permanganate solution used. The
titration must be performed slowly to insure accuracy, the permanganate
being run in at the rate of not more than a drop in a second, or three
drops in two seconds. The eye must become accustomed to the bleaching of
the indigo used, and select some one tint of yellow, as the end of
reaction is then possible to duplicate. That part of the material
analyzed, which is insoluble in acid and alkali of certain strength
after treatment for a definite length of time, at a definite
temperature, is called _crude fiber_, and it may be described as
follows: Select two grains of substance 200 CC. of 5 per cent.
hydrochloric acid; steam bath two hours, raising the liquid to a
temperature of 90 degrees to 95 degrees C. filtration on linen cloth,
washing back into beaker with 200 CC. 5 per cent. sodic-hydrate; steam
bath two hours, filtration on asbestos, washing with hot water, alcohol,
and ether, drying at 120 degrees, weighing, ignition and crude fiber
from loss in weight.
REAGENTS AND APPARATUS
(1). Hydrochloric acid whose absolute strength has been determined.
(a). By precipitating with silver nitrate and weighing the silver
chloride.
(b). By sodium carbonate, as described in Fresenius Quantitative
Analysis, second American edition, page 680.
(c). by determining the amount neutralized by the distillate from a
weighed quantity of pure ammonium-chloride boiled with an excess of
sodium-hydrate.
(2). Standard ammonia whose strength relative to the acid has been
accurately determined.
(3). C. P. sulphuric acid specific gravity 1.83, free from nitrates, and
also from ammonium sulphates, which are sometimes added in the process
of manufacture to destroy oxides of nitrogen.
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