CLASS I. Native albumens, occurring, as their name implies, in a natural state in ani mal tissues and fluids. They are soluble in water, and are not precipitated by very dilute acids, by carbonates of the alkalies, or by chloride of sodium. They are coagulated when heated to about 158° Fahr.
1. Egg-albumen. —This naturally exist; in an aqueous solution, forming a transparent yellowish fluid, from which it may be precipitated by strong alcohol. If the alcohol is immediately and rapidly removed the precipitated albumen will readily redissolve in water. If the alcohol is allowed to. remain, the precipitate forms a coagulum which is insoluble. Ether coagulates egg-albumen. Strong acids, especially nitric, produce coagulation like that by heat or the prolonged action of alcohol, and the coagulum does not redissolve on the removal of the acid. Nitrate of silver, acetate of lead, and cor rosive sublimate, cause precipitation without coagulation, but the precipitate will redis solve if the precipitant is removed. Strong acetic acid in excess produces no precipitate; but if the solution is concentrated the albumen is transformed into a transparent jelly, and a similar result follows the addition of strong caustic potash, a profound change being effected in both cases. A solution of egg-albumen turns the plane of polarization
of yellow light 35.5° to the left (— 35.5°). Strongly acidifying the solution with hydro chloric acid increases the left-handed polarization to — 37.7°.
2. Serum-albumen resembles egg-albunien, but is distinguished by the following char acteristics:. The rotatory power of scrum-albumen is for yellow light-56°, and it is not coagulated by ether; nor is it very readily precipitated by strong hydrochloric acid; and whatever precipitate occurs is easily redissolved by the addition of more acid, the reverse of what takes place with egg-albumen. Precipitated or coagulated serum-albumen is_ soluble in strong nitric acid, which coagulates egg-albumen. Serum-albumen is found in blood serum, and also in lymph, both that which is contained in the lymphatic vessels. and in the tissues, also in milk, chyle, and several pathological transudations, one of which may be mentioned, viz., the albumen which appears in urine in certain forms. of renal disease.