In principle, differential thermal analysis, DTA, is a technique which combines the ease of measurement of the cooling and heating curves discussed in Chapter 3 with the quantitative features of calorimetry which are treated in Chapter 5. Temperature is measured continuously and a differential technique is used in an effort to compensate for heat gains and losses. In the case of DTA, as also in calorimetry, the actual heat measurement does not rely on a direct measurement of the heat content. A heat meter, as such, does not exist. In volume or mass determinations (see Chapters 6 and 7, respectively), the total quantity of interest can be established with one simple measurement. In the determination of heat content, in contrast, one must start at zero kelvin and measure all heat increments and add them up to the temperature of interest. In DTA one derives the flow of heat, Q/t, from a measurement of the temperature difference between a reference materialand the sample.1 – 6