AbstractDTA has been widely used for many years and it has always been assumed that the technique is intrinsically secondary in that the determination of enthalpy changes requires calibration of the equipment. Recently the present authors have shown that this is not so, and under certain conditions DTA becomes an absolute method. A modification of the new technique has now been applied to a polymer and the results are presented here. The heats of dissolution and hence of fusion of various polyethylene samples have been measured, together with their densities. The results are shown to be consistent with those of other workers. No special accuracy or importance is claimed for the actual results, however, because the purpose of the paper is to introduce a new technique in a familiar polymer context. There is scope for improvement and extension of the procedures described here, and the status of DTA in polymer science will be increased in consequence. The use of a liquid system greatly facilitates the preparation and handling of the material under test.