The thermal decompositions of lithium, sodium, potassium, rubidium and caesium formates were investigated by a complex dynamic thermoanalytical method. The ratio of the products in reactions resulting in alkali metal carbonates and oxalates depended variously on the atmosphere used. Differences were found compared to isothermal investigations, in that the catalytic effects of bases could not be observed and the oxalate-conversion was lower. The formation of oxalate did not occur in the cases of lithium and caesium formates; the order for the other salts was sodium formate < potassium formate > rubidium formate.The thermal decomposition of an alkali metal formate is a complex process, the following reactions being possible:

The electrical conductivity (EC) changes of thallium(I) salts of fatty acids, which possess liquid crystalline phases, were investigated as a function of temperature. It was found that sharp EC jumps are associated with the phase transitions. The EC of the liquid crystalline phases depended not only on the temperature, the molecular weight and the geometry of the measuring cell, but also very sensitively on the heat treatment conditions which affect the relative magnitude of the EC in the mesophases.Study of these dependences revealed a "memory effect". An explanation is given for this phenomenon.We have already reported on the thermodynamic data of the polymorphic and phase changes and on the characteristics of the thermal decompositions of the thallium(I) salts of fatty acids [1 ]. From the homologue having five carbon atoms, these salts possess thermotropic liquid crystalline phases, which belong to the amphiphile smectic type [2-4]. As a continuation of this work we have thoroughly investigated the thermoelectrical properties of these compounds, paying special attention to the behaviours of their mesophases. ExperimentalThe thallium(I) salts of saturated, open-chain, non-branching monocarboxylic acids (C1 -C9, Ca.o, C14, C16, and Cas ) were produced, purified and analysed in the previously-described way [1 ].Three different types of cells were applied for the measurement of electrical conductivity: a crucible type for the simultaneous DTA-TEC (differential thermoanalysis-thermal electrical conductivity) measurements, which was made of platinum [5,6], a glass capillary type [5,7,8], and a micro-cell with gold electrodes evaporated onto glass slide surfaces.

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