An adiabatic calorimeter has been developed for determination of the purity of the reference compounds required for spectroscopic investigations. Two interchangeable calorimeters with volumes of 0.5 and 5 ml. are used. A complete determination, including calculations, usually requires less than 4 hours. Although the purity determination is based on the measurement of the melting point depression, this method, unlike conventional melting point methods, does not require a previous determination of the heat of fusion and the melting point of the pure compound. Instead, the method determines these quantities as part of the analysis. The calorimeter is used to measure the equilibrium temperature of the sample as a function of heat input as it passes from the solid state to the liquid state.

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