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.