On what principle does calorimetry depend?

Calorimetry is science. It is an act of measuring the amount of heat produced by a subject. The basic principle of calorimetry is the Law of conservation of energy: the sum of all energies must equal zero:

q1+q2 + ... = 0;

According to this Law, also it is important to note that heat going into a system is positive, and heat leaving the system is negative,