The next and last group is that of Food Substances containing alkaloids, which act upon the nervous system as stimulants or sedatives. The principal examples are Tea, Coffee, Cocoa, Tobacco, Hemp, and Opium.
Tea and Coffee have hardly any other properties in common than the possession of an alkaloid called Theine or Caffeine, which is identical in the two. Chocolate contains a peculiar alkaloid called Theobromine. Paraguay tea or “maté” is the only other substance extensively used as a dietetic infusion that contains theine; in South America it occupies the same position in domestic economy as Chinese tea does in this country. Case 46 exhibits the chemical analysis of a pound of ordinary good Chinese Tea; and in Cases 47, 48, and 99, contiguously placed, are numerous samples of tea from China, Japan, Java, Brazil, and East India.
The analysis of a pound of Coffee is shown in Case 50; and many samples of raw coffee from various parts of the world are exhibited. The visitor’s notice is directed to the printed descriptive label concerning Coffee, which is suspended near the case containing the analysis.
Cocoa is represented by the analysis of a pound of Cocoa paste in Case 53, and by a series of the fruit pods containing the seed or nuts, presented by Messrs. Fry and Son, of Bristol, as well as by various preparations and confections. The distinguishing feature of its composition consists in the large quantities of fat and albumen which it contains; so that Cocoa not only acts as an alternative through its theobromine, but as a force-producing and flesh and force-producing food. Samples of the commercial varieties of the nuts or seeds from various countries are exhibited.
Tea and Coffee Substitutes.
A variety of substances are exhibited in Case 49 in illustration of the use of the leaves of various plants for making potable infusions. The most important is Paraguay tea or “maté,” which contains the same alkaloid called theine, as the Chinese tea plant. A quantity of “maté” is shown, with calabash or dried gourd for making the infusion, and sucking pipe for drinking it. A large number of substances have been employed from time to time as substitutes for Coffee, and prepared in the same way. Many of them are shown in Case 52. In this country none of these so-called Coffee Substitutes have established themselves in public reputation, and are seldom sold. Some of them, however, are used as adulterants of Coffee.
Tobacco.
Although Tobacco has been only comparatively recently introduced amongst the inhabitants of the Old World, it is more extensively employed than any other narcotic. It is the produce of various species of the genus Nicotiana. The practice of smoking the leaves of these plants was introduced from the New World. The species, which is a native of America, and which supplies the greater proportion of the Tobacco smoked in Europe, is the Nicotiana Tabacum. The leaves of these plants contain an active and highly poisonous principle called Nicotine, which is the agent that produces the narcotic effect experienced in smoking. This narcotic effect resembles in some measure that of alcohol. Tobacco has, however, a less stimulant effect than alcohol, and produces, especially at first, a greater derangement of the general nervous system.
The chemical analysis of one pound of Tobacco is exhibited in Case 98. Cases 93 to 97 contain a series of specimens of the leaves of species and varieties of Tobacco cultivated in various parts of the world, with samples also of the Cigars and Tobaccos manufactured from them.
Examples of varieties of Snuffs used in this and other countries will be seen in Case 97. Snuffs are usually made from the stalks and ribs of tobacco leaves. Tobacco is liable to be adulterated with the leaves of other plants; these, however, can be detected under the microscope. Specimens of Tobacco adulterated with other leaves are illustrated in the diagram near the cases.