IN the literature of friction it has been generally assumed, often implicitly, that there is no causal relationship between wear and friction. Schnurmann1 has shown that the results of measurements of static friction on naked cadmium surfaces at temperatures down to — 100° C. indicate that abrasion cannot be the only factor responsible for the elementary mechanism of friction, and that an essential part is played by deformation. The following treatment, however, provides direct evidence for this lack of a causal relationship. It is shown that the work involved in that portion of the abrasion which actually results in wear is a negligible proportion of the frictional work.