Biliary acids combined with alkalies (bilin), 91.5 Fat, 9.2 Cholestrin, 2.6 Mucus and coloring matter, 29.8 Salts, 7.7 ----- 140.8 Bile is distinguished from the other alimentary secretions by the entire absence of proteids. The chemical composition of bilin, as compared with the organic parts of blood, is: Carb. Hyd. Nitr. Oxy. Sul. Bilin atoms, 76 66 2 22 Blood, 48 36 6 14 { Biliverdin, 16 20 2 5 Coloring matter, { Glycocholic acid, 26 43 1 6 { Taurocholic acid, 26 45 1 7 1 There seems to be some relationship between the coloring matters of the blood and bile; and it may be added, between these and that of the urine also; so that it is possible they may be, all of them, varieties of the same pigment, or derived from the same source. The quantity of bile discharged into the intestines is estimated to be about thirty to forty ounces secreted by an adult man in twenty-four hours. The purposes served by the secretion of bile may be considered to be of two principal kinds, viz., excrementitious and digestive. As an excrementitious substance, the bile serves especially as a medium for the separation of excess of carbon and hydrogen from the blood. Though one of the chief purposes of the secretion of bile may appear to be the purification of the blood by ultimate excretion, yet there are many reasons for believing that while it is in the intestines it performs an important part in the process of digestion. Bile has a slight solvent action on fats, and only a slight emulsifying power. Its functions generally may be considered thus: 1. It assists in emulsifying fatty portions of food, thus rendering them capable of being absorbed by the lacteals. 2. Bile facilitates the absorption of fatty matter. 3. Bile, like the gastric fluid, has a strongly antiseptic power, and may serve to prevent the decomposition of food during the time of its sojourn in the intestines. 4. Bile has been considered to act as a natural purgative, by prompting an increased secretion of the intestinal glands. 5. Another very important function appears to be that of so acting upon certain constituents of the blood passing through it, as to render some of them capable of assimilation with blood generally, and to prepare others for being duly eliminated in the process of respiration.