Abstract
An integral equation is given for the spin-correlation function G(t), which determines the free-induction decay at high temperatures. This equation is deduced by an equation-of-motion method where the full hierarchy of correlations (s1zd0+), (s1zs2zs0+) etc., is considered. G(t) is calculated for the case of CaF2 and is compared with the experimental results of Engelsberg and Lowe (1974) who extended the measurements to long times.