MESSRS. EDITORS—I have, on a former occasion, made some suggestions upon coffee-making ; and in pursuing the same subject, to show how the use of this beverage has increased in LJO years, I may state that in that time the production of coffee has increased from 10,000,000 pounds annually, to 500,-000,000 pounds, or fifty times the original amount. In Europe alone, during the last thirty-six years, the consumption lias increased from 150,000,000, to 250,000,000 pounds. It is a curious historical fact, that in Arabia* where the use of roasted coffee originated, it was used to keep awake the worshipers in the temples ; and an immense number of coffee-drinkers were always to be found in the coffee-houses, especially in Constantinople (where the first coffee-house was established in 1554) ; so much so, that the churches were emptied, and therefore a tax was levied on cof-fee-drinkerB by the Sultan. The first coffeehouse was opened in London in 1652, by a Greek named Paqua, and shortly afterwards another one was opened in Paris. The coffee bean consists of a homogeneous tissue of cells, and contains from 15 to 20 per cent of a substance called protein, which is also found in the fibrin of the human body, and there is of the caffeate of coffee and tannin combined with alkali and caffeine, about 5 per cent, and 13 per cent of fat, sugar, and gum ; the rest is lignin, albumen, and water. The process of roasting changes the tannic and coffee acids into an agreeable aroma, and according to the chemist Payen, most of the caffeine is formed at the same time. As the aroma exists in such small quantities, it is driven off at too high a temperature, aud the fat and sugar is also destroyed, it will be seen that much of the flavor is due to the roasting, which yet requires some study to determine the exact temperature at which it should be performed; this much, however, is hnownt that when the heat is about 200, much attention should be paid to the color, for somewhere about this is the proper temperature. Coffee may be improved by washing in cold water and being properly dried before roasting. I Lave previously explained the best method of performing this operation. By the aid of chemistry it has been discovered that there is the greatest similarity between the beverages used as stimulants, and obtained from different plants in all parts of the world. For example, in 1820, the German chemist Runge, discovered the caffein of coffee, and a few years after, Oudry, the French chemist, discovered the thein of tea—both crystalline bitter substances, containing a great quantity of carbon and hydrogen, and but little nitrogen or oxygen. Mulder, a German, first demonstrated their similarity. The cocoa bean was next investigated, and its essence discovered, and called theobromin, or "nectar for the gods." Science, after showing that the principal beverages of the civilized world are alike, did not stop here, for the Bavarian naturalist Martius, found that the fruits of a plant in South America, known there as guai'una, contains also a substance like caffein, when roasted, and infusions made, as is done by the natives of the country where it grows, and it produces the same effect as coffee and tea. The same is also true of matt?, or Paraguay tea, and of the leaves of the camim, also used there. If we compare particularly the roasted leaves of tea with the roasted beans of coffee, we find the difference consists in tea possessing more etlieric or volatile oil, which is replaced in coffee by an empyreumatic oil; there is no albumen in either infusion. Used to excess, coffee increases the pulsation, produces congestion of the brain, and a consequent excitement of the whole nervous system ; the constant mutations of substances in the body is retarded, and less urea, chloride of sodium, and phosphates are found in the secretions, all of which is due to the empyreu matic oils. Both tea and coffee diminish the appetite, by retarding the processes of digestion ; yet at the same time they improve the effect of the food, by lengthening the time of its change into substances necessary for assimilation with the body. The same remarks apply equally to theobromin, only that it is much richer in oils and fats. In Turkey, the sediments of coffee are used as food ; on the shores of South America the leaves of tea are eaten, and also by some tribes in Asiatic South Russia, and in some parts of China. In this case it is the nitrogenous albumen which affords the nutriment, L. K.BRMSACH.
This article was originally published with the title "Coffee, Tea, and Cocoa" in Scientific American 13, 28, 219 (March 1858)