The principle of the method of mixtures states that the heat lost by a hot body is equal to the heat gained by the cold body when they are mixed together and attain the same temperature. This principle is based on the law of conservation of energy.
Heat energy lost by the hot body = Heat energy gained by the cold body. This is called the principle of the method of mixture. It is based on Newton’s Law of Cooling, which states that when a liquid is heated of higher temperature and placed to cool. Then the rate of heat lost by a temperature of the liquid is directly proportional to the difference in temperature of the surrounding.
The other name to it is the principle of calorimetry. This principle is based on the law of conservation of energy.
The calorimeter is a device used to measure the heat flow of a chemical or physical reaction. Calorimetry is the process of measuring this heat. It consists of a metal container to hold water above the combustion chamber and a thermometer to measure the temperature change. The principle of calorimetry is heat lost is equal to the heat gained.