Collier's New Encyclopedia (1921)/Coagulation

COAGULATION, the act or process of being coagulated, or of changing from a liquid to a curd-like semi-solid state, produced without evaporation and without crystallization. It differs from congestion in not being attended by a fall of temperature in the substance coagulated.

When blood is drawn and allowed to stand it emits a “halitus” or exhalation, which has a faint smell. In three or four minutes a film overspreads the liquid, commencing at the circumference and gradually spreading to the center. Two or three minutes later the lower part of the blood, in contact with the vessel, becomes solidified, and then the whole mass, only about eight or nine minutes being needful for the whole process from first to last. In about 15 or 20 minutes a thin serum begins to exude from it, and goes on to do so for two or three days.