No structure similar to those just described, except spiral vessels, and no principle allied to caffeine or to the aromatic oil before-mentioned, have ever been found in any of the various substitutes for coffee.

Structure of genuine coffee; A, "flights" with a few spiral vessels; B, quadrangular cells which form the bulk of the berry.

Adulterations.-Coffee, when roasted and ground, is seldom mixed by dealers with any substances except roasted and ground chicory, or some vegetable substitute for chicory, similarly prepared. Other materials are occasionally employed, but the use of them is very limited, both because they are illegal and not generally acceptable to the public taste.

Since the equalisation of the duties on coffee and chicory, the revenue has ceased to interfere in any manner with the sale of mixtures of these articles, it being no longer required, as was until recently the case, that the vendor, if he wished to avoid penalties, should label his packages with a description of their contents. Although the law prohibiting the manufacture or sale of substitutes for coffee remains at present unchanged, its provisions, so far as regards chicory, have been suspended; it is unnecessary, therefore, under the existing regulations, to procure samples of coffee merely for the purpose of ascertaining whether they contain an admixture of chicory, or of substances applicable to the uses of chicory or coffee.

Under the head of Chicory, will be briefly noticed the methods of distinguishing between genuine chicory and substances such as beet, mangold-wurtzel, &c., that are likely to be present in coffee mixtures. A very concise account of the subject will suffice, as inquiries of this kind can be but of little service in the present state of the regulations affecting the sale of coffee.

It has been asserted on somewhat reputable authority, that baked horse liver, rotten wood, and other repulsive forms of organic matter are occasionally ground up with coffee by fraudulent retailers, but the evidence in support of this statement is altogether unsatisfactory, and it is certain that no such adulterants have ever been detected in any of the numerous samples purchased from all classes of traders, and analysed at the Inland Revenue Laboratory. It is indeed difficult to conceive that the use of the smallest quantity of these ingredients could fail to attract the notice and excite the disgust of the humblest consumers of coffee.

Imitation or artificial coffee beans, professing to consist of ground coffee and sugar, but really made up in a rather ingenious manner of powdered chicory and other cheap roots, were, a few years since, prepared on a large scale at Liverpool, by a patented process, but the fraud was too gross and palpable to succeed for any length of time.

Brick dust and red ochre-other alleged adulterants of ground coffee-would be sure to betray their presence by falling to the bottom of the vessel in which the decoction of coffee was allowed to stand. Roasted corn, peas, beans, acorns, burnt sugar, and raspings of crusts of bread, are much more available materials, where it is sought to replace chicory, or the various roots allied to it, with ingredients of a less expensive character.

Officers should observe, that the simple test which formerly sufficed to indicate in a general way the purity of a sample of ground coffee,—namely, that of dropping a little of the suspected powder into a glass of cold water, and then remarking whether or not a yellowish brown colour quickly appeared and diffused itself through the liquid-is no longer useful in revenue inquiries, as the reaction in question, which is common to all substances containing a large proportion of caramel, might be given by chicory, now an allowed constituent of coffee mixtures.

CHICORY.

Chicory, properly so called, is the root of the wild endive or succory (Cichorium Intybus). In this country the growth of it is confined almost entirely to Yorkshire, and even there the quantity under cultivation has been of late years, very limited, as it is not a generally remunerative crop, and the chicory of foreign production is of greatly superior quality. That which comes to the English market is raised chiefly in France, Belgium, and Guernsey.

After the plant has ceased flowering, the long tap-root is taken up, well-washed, cut into slices, kiln-dried, and then roasted in the same manner as coffee, and ground while crisp between fluted rollers.

The other roots used as ingredients of coffee mixtures are similarly prepared ; all of these contain sugar in large but variable proportions, both before and after roasting a fact which may be regarded as a leading characteristic of this class of substances. The following are the per-centages of sugar in different roots when

dried, as well as in various coffees, as determined by Messrs. Graham, Stenhouse, and Campbell, in an elaborate inquiry undertaken by them in the year 1852, for the Board of Inland Revenue.

Sugar in Coffee, Chicory, and other Roots, before and after Roasting.

From the above table it may be inferred that as roasted coffee contains merely a trace of sugar, an excess of this ingredient, in any sample submitted to examination, affords a strong presumption of the presence of some roasted root.

Substitutes for Chicory.-The microscopical appearance of chicory root does not in the least resemble that of the coffee bean. Chicory root consists of three structures as shown in Fig. 30.; A, represents the thin-walled cells which form the chief bulk of the root. B, tubes marked with pits, bars, or dots, and usually termed pitted or dotted tissue. C, branching tubes or vessels termed laticiferous tissue, through which circulates, in the fresh root, a turbid, milky fluid called latix. It is important to observe, that none of these three structures are found in coffee; hence the detection of chicory in coffee mixtures is rendered both easy and certain.

Dandelion Root closely resembles chicory in its microscopical structure, and it is somewhat difficult, in consequence, to distinguish between the two. The latix tubes of the dandelion are, however, in general larger, better defined, and more numerous than those in chicory, while the pitted vessels are generally smaller and more abundant; the cellular tissue, also, includes a greater number of brick-shaped, elongated cells.

Mangold-wurtzel, differs from the preceding, in the total absence of laticiferous tubes, and in the cellular tissue being much larger and more abundant. Beetroot, in its microscopical characters, closely resembles mangold-wurtzel, as might be expected from the family connexion of the two.

The foregoing substances constitute the ordinary and most probable substitutes

for chicory, but it is difficult for an unpractised observer with a microscope to obtain decisive proofs of their presence, and there is not any known chemical test which will distinguish them from chicory or from each other.

As regards the admixture of chicory with other vegetable substances than the various roasted roots, it may be remarked generally, that any of the cereals, such as wheat, barley, rye, &c., can easily be recognised under the microscope, after a little practice, by the peculiar appearance of the seed-coats of these grains. The

thick-walled, hexagonal cells, filled with minute granular contents, and the hairs proceeding from the apex of the grains, afford a ready means of detection in this case. Roasted beans and peas are best identified by the unusually large starch granules contained in them, which become gelatinous when boiled with caustic potash, and also by the peculiar structure of the skins, should fragments of these be present. The intense blue colouration produced by iodine supplies a good general test of the presence of roasted corn, pulse, or acorns. But the entire subject of the possible adulterations of chicory, since the recent increase of the duty on that article, has yet to be investigated and reduced, as far as possible, to a system commensurate in point of clearness with the importance it may acquire as a branch of official study.

TEA.

Tea consists of the prepared leaves of several varieties of an evergreen shrub known botanically as Thea sinensis, and belonging to the same family of plants as the camellias. It is a native of China, but is now cultivated also in India, Java, Penang, Rio Janeiro, &c. Black and green teas are obtained from the same plant, the differences between them depending merely on the mode of cultivation, the season at which the leaves are collected, and the manner in which they are dried. The tea plant arrives at maturity in about four years, and generally attains a height of from three to six feet. The leaves are plucked at different seasons of the year, the first gathering taking place in April and the last in September.

The form and size of the leaves vary considerably according to the time of the year at which they are plucked. In the smaller and younger leaves the arrangement of the veins is scarcely perceptible, but in those of older growth it is very distinctly marked. In all, the margin is delicately serrated, the serrations being deepest on the larger-sized leaves.

In the preparation of black tea, the leaves, as soon as gathered, are placed in a heap, and submitted to a slight fermentation by which they become flaccid and much darker in colour. They are then rolled by the hand into the curled up form so familiar to every one, and are dried or slightly roasted over a charcoal fire. After being subjected a second time to the twisting and drying processes, the leaves are packed into chests for the market.

The chief varieties of black tea are Pekoe, Souchong, Caper, Congou, and Bohea. In preparing green tea, the fermentation process is dispensed with, but the leaves are first heated in a metal pan termed a Kno, and then twisted or curled, and again heated, stirred, and twisted.

The principal varieties of green tea are Gunpowder, Imperial, Twankay, Hyson, Young Hyson, and Hyson Skin.

The chief constituents of tea are tannin, gum, a crystalline body termed theine, which is identical with the caffeine of coffee already described, and a volatile oil to which the aroma is due, and which it appears, is produced during the roasting or drying of the leaves.

Adulterations. In addition to the adulterations practised in this country, tea is largely sophisticated in China, especially the green variety, and hence great difficulty arises in suppressing the fraudulent practices resorted to by British dealers. Occasionally, leaves other than those of tea are added in China, but the adulterants mostly used there are Prussian blue, indigo, Dutch pink, tumeric, French chalk, and gypsum, to give the leaf the green hue so much preferred by the public. An excess of fine sand, as well as small particles of quartz coloured with plumbago are frequently found in tea when imported. These substances have the effect of considerably increasing the weight of the tea.

The adulterants commonly employed in this country are, exhausted tea leaves twisted into the proper form with gum water, and then dried; leaves of various British plants, as the sloe, cherry, oak, poplar, elder, &c. ; catechu; plumbago, or black lead to face black tea; and in the imitation of green tea, similar substances to those used by the Chinese.

The admixture with exhausted tea leaves can only be ascertained with certainty by a careful chemical analysis and a comparison of the result with the analysis of