What is principle of calorimetry ?

Explanation

Heat gained = heat lost ,When a body at a higher temperature is brought in contant with another body at lower temperature the heat lost by the hot body is equal to the heat gained by the cold body provided no heat is allowed to escape to the surroundings .
Heat lost= Heat gained
`Q_("gain" ) =- Q_("lost")`
`Q_("gain ") + Q_("lost") =0`