As noted earlier, the text generally has been revised to include discussion of or a t least some reference to much of the important research in reaetion mechanisms published since the appearance of the first edition. To be sure, one can find some significant work which has been omitted. One example is Ingold's paper ( J . Chem. Soc., 4054 [19601) on inductive us. steric effects as the controlling factor in determining the direction of E2 eliminations of onium salts, which one might have expected t o see mentioned in Chapter 8. Another is the very limited mention (p. 155) given to Winstein's studies of specid salt effects in solvolysis reactions. However, when one considers the everincreasing volume of physic&organic literature and the need to keep the b w k to a reasonable size, some such omissions were doubtless inevitable. All told, this edition represents a significant updating of the original, and because of the rapid paec of rescarch in reutetion mechanisms, its purchase to replace volumes of the first edition now in personal or institutional librarie. seem indicated.
JOHN L. I
