percentage of such sugar by the copper test would be confirmatory of the presence of caramel.

MICROSCOPIC EXAMINATION.

In the detection of the adulterants of coffee, the aid of the microscope is always resorted to. It becomes, therefore, a matter of great importance to gain some clear knowledge of the structure of the tissues of roasted coffee, and also of the various substances which are likely to be employed in its sophistication.

In coming to a decision as to the kind of adulterant which may be present in coffee, or any other article in which the microscope is relied upon for detecting the presence of a foreign substance, it is not enough, usually, to trust to any mere drawing or representation of the adulterant indicated. It is always advisable to examine under like conditions a portion of the particular seed or root which it is supposed has been added, and when the percentage is required, to make up mixtures representing different degrees of adulteration, and to judge, from the number of foreign particles on the slide, the extent to which they have been added to the pure coffee or other article.

In some instances where a foreign substance is shown to be present by the microscope, and it is possible to identify it, the knowledge thus obtained becomes of the utmost value in indicating the particular chemical and other tests which should be applied in order to determine the proportion in which the adulterant is present.

I. ROOTS.

All the roots that can be employed with advantage for mixing with coffee are very similar in structure. They mainly consist of a mass of cells, among which occur bundles of jointed tubes, the sides of which present the appearance of being marked with bars or pits.

When moistened with water the particles become soft, while those of coffee remain hard and difficult to bruise.

Chicory. The tissues composing chicory-root are shown in Fig. 14. A represents the pitted tubes, which are present in considerable quantity and are highly characteristic. They resemble

long jointed cylinders, and are distinctly marked with bars or pits. The joints frequently overlap each other, and give to the cylinders an uneven appearance. B represents what are called laticiferous or milk vessels. They are narrow, transparent, branching tubes, filled with latex. In the roasting of the root the latex is dried up, and the interior of the tubes presents the appearance of being filled with granular matter, as shown in the drawing.

c represents the cellular tissue, which consists of round or oval, smooth, and thin-sided cells. Those composing the bark or skin are somewhat angular, as seen at D.

Chicory is free from starch.

The size of the dotted tubes, the peculiar appearance of the

joints, and the presence of the laticiferous vessels, afford a ready means of distinguishing chicory from the other root adulterants. Dandelion root has a structure somewhat similar to that of chicory, but the pitted tubes of the former are narrower and more regular, and the laticiferous vessels more abundant and better defined than the corresponding tissues of the latter.

Mangold Wurzel.-The microscopic appearance of the tissues composing mangold wurzel is shown in Fig. 15. The pitted

tubes represented at A are very abundant and large. Many of them have blunt oblique ends, and on trituration they break up into shorter tubes which terminate obtusely. The cells of the tissue shown at в are larger than those of chicory; they are very transparent and thin-sided, possessing little cohesion, the slightest trituration causing them to separate. The cells composing the outer skin are angular.

The absence of laticiferous tissue and the size of the cells serve to distinguish mangold wurzel from chicory. Like the latter, however, mangold wurzel is free from starch.

Turnips.-The turnip when roasted and ground presents the appearance shown in Fig. 16. It is composed of cellular, pitted, and woody tissues. The first two of these are very similar to the

corresponding structures in mangold wurzel, except that the cells are more irregular in size, and have no tendency to separate, but hold together with considerable tenacity. The woody tissue, which is present in abundance, breaks up on boiling into bundles of short flakes having a striated appearance.

The absence of starch and the presence of the woody tissue make the identification of turnip comparatively easy.

Carrots.-The cells of the cellular tissue of this root are small, transparent, and thin-sided, and those of the skin or bark are angular in shape and very regular. The pitted tubes occur amongst the cells, and, excepting that they are somewhat smaller, resemble those of turnip and chicory.

Carrots contain starch, the granules of which are very small and round, and in some cases muller-shaped, with distinct central hilums.

Parsnips.-The tissues of parsnips so closely resemble in form and size those of carrots, as to render it almost impossible by these characters alone to distinguish between them when roasted and ground. The cells of parsnips, however, contain a much greater proportion of minute starch-grains than those of the carrot, and there is a greater irregularity in the size of the granules.

Carrots and parsnips differ from chicory in not containing laticiferous tissue, and also from chicory and the other root adulterants in containing starch.

II.-SEEDS.

Seeds are usually best detected by the microscope, and, as neither they nor their seed-coats contain pitted tissue, there is little difficulty in distinguishing them, even when roasted and ground, from roots.

When a seed is roasted and ground with its seed-coat, there is usually to be found in the structure of the latter some