On account of the peculiar properties of the cocoa bean, its preparations merit a place on our tables for two reasons: In addition to being like tea and coffee, the material for the preparation of a pleasant and exhilarating beverage, it is a valuable food material. Not only is it much richer in nutritive substances than tea or coffee, but both the soluble and insoluble portions become a part of the beverage, while only the constituents soluble in hot water are obtained in the beverages prepared from tea and coffee. The investigations of Stutzer (see below, under head of nitrogenous constituents) and others clearly prove, however, that the food value of cocoa preparations has been greatly overestimated and that many of the present modes of preparation do not develop in the highest possible degree the pleasing aroma and flavor. The inventive energy of many manufacturers seems to be spent on the production of a highly nutritive and easily digestible preparation; the valuable fat is removed and the delicious aroma and flavor destroyed by chemicals for the ostensible purpose of rendering more digestible a residue of doubtful food value.

The more important constituents of the husked cocoa bean are fat, theobromine, the nonalkaloidal nitrogenous substances, starch, the coloring matter called cocoa red, and the mineral matter.

The fat, cocoa or cacao butter, in consequence of its quantity and peculiar excellence, is unquestionably the constituent of the cocoa bean possessing highest food value. It usually forms 45 to 55 per cent of the husked bean, rarely falls below 45 per cent, and only one recent analysis shows as low as 36 per cent. At ordinary temperatures it is a white, or slightly yellowish, brittle solid, having a pleasing taste and odor, and showing but little tendency to become rancid. Its melting point being below the temperature of the body, insures its being presented in liquid form to the action of the digestive juices. Chemically, it is a mixture of the glycerides of stearic, palmitic, oleic, and arachidic acids.1 It is readily soluble in ether, acetic ether, chloroform, oil of turpentine, and hot absolute alcohol, but only 1/2 per cent remains in solution when the alcohol becomes cold;2 fully soluble at ordinary temperatures in 2 parts ether, 1/2 part of benzol, 100 parts of cold and 20 parts of hot alcohol.3

The physical and chemical constants of value in investigations for identity and purity have been arranged in tabular form in the table given on page 938. In addition to numbers there given, Valenta4 has found the temperature at which the solution in hot glacial acetic acid becomes turbid to be 105° C.

The low melting point, the little tendency to become rancid, and other properties render cocoa butter peculiarly suitable for the basis of many pharmaceutical preparations. This by-product of the manufacture of cocoa preparations has, therefore, a well-established place in commerce. The Shipping and Commercial List and New York Price Current for October 7, 1891, quotes foreign cocoa butter at 31 to 37 cents per pound and domestic at 40 to 42 cents per pound.

Schaedler2 thus describes the process of extraction on the large scale:

In earlier times the ground and roasted beans were boiled with ten parts of water, the fat skimmed off, and the residue pressed out. The beans are now roasted, husked, and very finely ground. The mass is heated to 70°- 80° C., packed in sacks of ticking, and submitted to pressure between previously warmed or steam-heated plates. The fat expressed, about 30-35 per cent, is filtered through dry filters. The pure residue, containing 10 -15 per cent of oil, is made into chocolate. For the preparation of an entirely fat-free cocoa powder, the roasted and ground beans are exhausted with benzine or ether.

1 Benedikt, Analyse der Fette und Wachsarten. Schaedler, Die Technologie der Fette und Oele des Pflanzen- und Thierreidis.

2 Schaedler, Die Technologie der Fette und Oele des Pflanzen- und Thierreiehs.

3 Blyth, Foods: their Composition and Analysis.

4 Dingler's polyt. Jour., 252, 296; Zeitsch. f. anal. Chem., 24, 295.

Theobromine, the alkaloid of cocoa, is very closely related chemically (it is dimethyl xanthine, C5H2(CH3)2N4O2, while caffeine is trimethyl xanthine, C5H(CH3)3N4O2) to caffeine, the alkaloid of tea and coffee, and has similar effects on the system; the power possessed by the beverages prepared from these substances, "to cheer and not to inebriate," being largely due to the presence of these alkaloids.

Separated from the bean, it is a white powder, permanent in the air, crystallizable in microscopic rhombic needles, and having a very bitter taste. While neutral in reaction, it acts as a weak base, uniting with acids to form crystallizable salts, which become basic on treatment with water; its salts of volatile acids give up their acids on heating, at or below 100° G. According to Blyth,1 it begins to sublime at 134° C., and yields distinct crystals at 170° C. and above; Keller, 18542, reports the subliming point as 290° - 295° C.; other writers note it as about 290° C. Treumann3 has reported its solubility in water to be 1 in 148.5 at 100° C, and 1 in 1,600 at 17° C.; in absolute alcohol, 1 in 422.5 at the boiling point, and 1 in 4,284 at 17° C.; in boiling chloroform, 1 in 105. Husemann4 states its solubility in water to be 1 in 55 at 100° C., 1 in G60 at 20° C., and 1 in 1,600 at 0° C.; in cold alcohol, 1 in 1,460, and in boiling alcohol, 1 in 47; in cold ether, 1 in 17,000, and in boiling ether, 1 in 600; more soluble in chloroform and warm amyl alcohol than in water, less soluble in benzol, and insoluble in petroleum ether.

1 Op. cit., note 3, p. 936 of this work.

2 Op. cit., note 3, p. 938 of this work.

3 Archiv. d. Pharm., [3] 13,5; Jahresb. d. Chem., 1878,872. 4 Husemann's Pflanzenstoffe.