Experimental evidence based on the peak area measurements of the endothermic reaction of kaolinite and also (kaolinite): (inert material) mixtures was produced to show that the use of an optimum amount of material (200 milligrams for the experimental set-up used) gives the nearest approach to the quantitative reproduction of peak areas in relation to the mass of active material. It was also shown that such an optimum amount of active material increases to a maximum the ability of the method to semi-quantitatively resolve reactions with the same sign which occur at closely separated temperatures. The experimental evidence refers to the resolution of the two low temperature moisture peaks of calcium montmorillonite between 100-200°; and also the pyridine-montmorillonite system.