Direct recording of the heating curve:
While a sample is heated at a constant rate, the temperature function T, is linear up to the moment whenever the sample undergoes modification, its slope represents the rate of heating that remains constant.
At the moment, while an exothermic and endothermic change takes place, the shape of curve changes as display in Figure. An exothermic reaction causes a rise in heating rate although endothermic reaction causes a decrease in heating rate. The main drawback of this technique is its sensitivity, since small changes within the temperature cause small deviation in linearity of the curve that sometimes are not observable. Then, small temperature modifications occurring in the sample are commonly not detected through this method. Because detector thermocouples are opposed to every other, small difference among Ts and Tr could be detected after appropriate voltage amplification. Therefore very small sample size might be used in this method.
Therefore recording of the differential curve is advantageous since it can record the small change in enthalpy in which is not accompanied through a modification in weight.