MEASUREMENT OF THE THERMAL ACTIVITY OF DIELECTRIC LIQUIDS WITH AN ACCURACY OF 104 P. V. Lebedev-Stepanov and G. G. Spirin UDC 536.22 A method of measuring small ( 10-4) relative changes in the thermal activity of liquids is developed. A theoretical substantiation of its accuracy is given based on an investigation of the factors responsible for errors in the experiment. Results of experiments on a study of the temperature dependence of the thermal activity of a solution of polystyrene in toluene are reported. JEPTER74920199918 JEPTER7492018