Coffee was introduced into Europe a few years later than tea. It is derived from Coffea arabica. The seeds, which are used in the manufacture of the beverage, develop in pairs in a fruit that resembles a cherry. Different varieties of these seeds or beans are produced in different countries, each having a characteristic flavor.

To make the bean brittle, so that it may be ground easily, and to develop its flavor more perfectly, it is roasted. This should be done shortly before it is used, as the flavor is lost by keeping. Roasting causes a loss of from 5 to 20 per cent, of the caffein. The small amount of saccharine matter that coffee contains is also almost completely lost. Mocha in the raw state contains 9.55 per cent, of this, and when roasted, only 0.43 per cent. The fats or oils in it are increased. The most important of these oils is caffeol, which gives to roasted coffee its aroma. If two ounces of powdered coffee are used to make a pint of the beverage, the latter will contain approximately 3.5 grains of caffein and 6.5 grains of tannic acid. Each cupful will contain about one-half as much. Caffein is chemically trimethylxanthin and is closely related to xanthin, uric acid and the other purin bodies.

Coffee is frequently adulterated; such substances as peas, beans, acorns, and, more frequently, chicory are used for this purpose. The last is thought by many to modify the flavor of coffee agreeably, and it is not detrimental. Caramel is also occasionally used as an adulterant.

The beverage is made in several ways: Sometimes boiling water is filtered through finely ground coffee. By this process, however, one-half less of the coffee is dissolved than by the other methods. It may be infused, the ground coffee being put into boiling water and allowed to stand in it for some minutes in a hot place, but without boiling. In Turkey, coffee-beans are powdered and a decoction is made from them by putting the powder in cold water, which is then heated to boiling. This beverage is not strained. If coffee is boiled for some time, it loses its aroma, contains a larger percentage of tannic acid, and becomes more indigestible.

Both the caffein and the oil in coffee are stimulants. Caffein affects especially the central nervous system. Under its influence mental processes are quickened, the mind is made wakeful and restless, and if a sense of weariness exists, it is lessened. Respiration grows deeper, the heart beats with more force and rapidity and the pressure of blood in the arteries is increased. Coffee is a mild laxative to some persons. It increases tissue waste. In no sense is either tea or coffee a food, but sugar and milk added to them may give them food values.

Coffee is variously tolerated by different persons. Those who are nervous are made more so, and they are often made sleepless by it. Others feel only an agreeable stimulation. Many acquire a tolerance of coffee that makes them unconscious of its ill effects. Dyspeptics generally cannot drink it, especially if cream and much sugar are added to it. It is comparatively seldom that illness caused by coffee-drinking is seen, although it is not uncommonly observed from excessive tea-drinking. Soldiers and other bodies of men subjected to severe physical strain depend upon coffee to lessen their consciousness of fatigue. As a rule, they prefer it to tea. Its use improves the feeling of well being in soldiers so quickly that their officers regard it as a necessity.

Numerous substitutes for coffee and tea have been devised. The substitutes for the former are usually made from grains. They possess a somewhat similar aroma and flavor, but do not contain caffein or other stimulating properties. They are not, however, better digested than coffee. Mate, or Paraguay tea, is extensively used in South America. It is a native product, containing a small amount of caffein and considerable tannic acid. It produces the same ill effects that tea does, but it is drunk in a very dilute form and before the tannic acid has been extracted; therefore large amounts can be taken with comparative safety.