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Deviations from Matthiessen's rule (DMR) have been measured in five dilute PtTi samples. containing from 0.1 to 1 ato, Ti3 between 6 and 18 K. These data have been fitted to two models, pi-. a recently proposed empirical scheme and a two band model (although the validity of the latter model in this host has considerable doubt associated with it). Both approaches appear capable of reproducing the data. The characteristic parameters pb ( T ) and Kj'(T) of the empirical scheme are estimated, and the latter one shown to obey a power law dependence Kf(T) r T", n = 3.1 & 0.3, at these temperatures, in agreement with previous (but less extensive) estimates in this host. In the two band approach, the parameters fi and 7 which characterize this model. both vary rapidly with temperature below 18 K, with j3 increasing but y decreasing with increasing temperature. Both parameters however appear to extrapolate smoothly to the values deduced for them from a previous higher temperature study.