Part 1 of this investigation describes a formula with two time constants and the methods used to determine these. The formula is used to transform the signal curve of a heat flux calorimeter into the curve of a reaction-induced source heat flux. Because a mathematically exact procedure must be reversible, Part 2 deals with the calculation of the signal curve as a response to an inconstant source heat flux. A mathematically exact solution is derived for the case of a source heat flux that is linearly variable with time. It is then shown how reaction-kinetic models can be verified by thermal analysis.