At first glance it may seem presumptuous to want to add yet another to the numerous books on Differential Thermal Analysis (DT A). Thermoanalytical methods have been in use for some time, as shown by the more than five thousand publications containing DT A or TG curves listed by SMOTHERS and CHIANG in the bibliography to their handbook and abstracted in the several volumes of Thermal Analysis Abstracts (TAA), edited by J. P. REDFERN for the International Con­ federation for Thermal Analysis (ICT A). Every three years the proceed­ ings of ICT A meetings are published, bringing the latest results of thermoanalytic research. There is also the Scifax DT A Data Index, edited by R. C. MACKENZIE (1962) and modeled on the ASTM pattern card index (used for X-ray investigations), a compilation of the DT A data for several hundred minerals, and inorganic and organic materials. The theoretical foundations of thermogravimetry and DT A have been described in detail by LEHMANN, DAS and PAETSCH (1953), R. C. MACKENZIE (1957, 1970), DUVAL (1963), WENDLANDT (1964), GARN (1965), F. PAULIK et al. (1966), SMOTHERS and CHIANG (1966), and KEATTCH (1969). Thermoanalytical results are strongly influenced by various factors relative to preparation and equipment (see 1-2. 4 of this study). This is the reason why we frequently find, in these books as well as in the Scifax-Card catalog, contradictory data on the same substance.