If the experiment be first made with infusion of pure coffee of a certain strength, and afterwards with additions of known quantities of chicory, keeping these for comparison, the quantity of chicory in a mixed sample may be thus determined.[2]
A simple means of detecting the chicory in ground coffee is as follows:
Throw about a tea-spoonful of the suspected coffee in a wine-glass of water, and stir the mixture with a spoon. If
[Illustration: A Fragment of Roasted Coffee, being magnified 140 diameters.]
the coffee be pure, it for the most part floats, becomes very slowly moistened, even when shaken up with the water, and communicates scarcely any colour to the liquid; very gradually it imbibes water; the liquid acquires a very pale sherry tint; and at the end of several hours the greater part of the powder is found to have fallen to the bottom of the glass. If, however, it be chicorised, the presence of chicory (genuine or spurious) will be readily detected, by a portion of the suspected powder rapidly sinking and communicating to the liquid a reddish-brown tint, which will be more or less deep according to the amount of chicory present.
If the coffee be adulterated with what is called Hambro’ powder (roasted and ground peas, &c., coloured with Venetian red) or roasted corn, we have a further test in iodine, which communicates a purplish or bluish-red tint to the water to which either of these substances has been added. The preceding test is sufficiently delicate and valuable, in all ordinary cases, for detecting chicory in coffee; but to those familiar with microscopic investigations, the microscope furnishes another mode of proceeding: fragments of dotted ducts being found in chicory, but not in pure coffee. They are not met with, however, in great abundance; and some patience and care, therefore, are requisite in searching for them. The starch grains of Hambro’ powder are readily detected by the microscope, as also the blackening effect of a solution of iodine on them.
Plate 10 represents the structure and character of genuine ground roasted coffee, and of a fragment of roasted chicory-root, showing the dotted or interrupted spiral vessels which pass in bundles through the central parts of the root, magnified 140 diameters; copied, by permission, from Dr. Hassall’s work on “Food and its Adulterations.”