ERRATA 1960 Vol. 14 Page 4 262 265 294 295 296 303 308 314 Ref. 18. The authors should be Clauss Plass Boehm and Hofmann. First line after eqn. (12). For Hi = j’ #i H #i and& = $ $C H $ C read Hi = $ #i H $id7 and Hc = J $c H &dT. Second line after eqn. (1 7). For resonance read cohesive. Ref. 14 should read Lauger Martin and Miiller Helv. Chim. Acta 1944 27 892. Ref. 25. For 1914 read 1913. Ref. 31 should read Haynes and Plimmer Chem. and Ind. 1954 1147. Ref. 62. For 326 read 3495. Third line after formula (42). For pK read pKa. Ref. 90 should read Lecoq Bull. SOC. chim. France 1951,18 183.