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Discrepant interpretations regarding the frequency of the C=S stretching mode are reviewed and assignments of frequencies for the vibrational modes of the xanthate group, S -0 -C~ , are presented."s-;\ band a t 1020-1070 cm-I is assigned to the C=S stretching mode. Bands a t 1200 cm-1 and 1110-1140 cm-' are ascribed to the stretching vibratiolis of the C-0-C linkage. The effects of the alkyl hydrocarbon chain length and of metal atorns (alliali metals, copper, and zinc) in displacing solne of the frequencies are recorded.

Stress corrosion cracking of alpha brass in ammonia solutions containing copper-ammonia complexes is most rapid in the pH range 6 to 7, where weight loss corrosion is insignificant, Linear relationships were found for (a) log 1/tc (tc = cracking time) vS log Cu++ (initial copper concentration) and (b) l/tc vs 1/T (T = absolute temperature). Oxygen appears necessary for general corrosion and cracking at pH values above 8. Rapid cracking is interpreted in terms of a drastic surface free energy decrease caused by the adsorption of an intermediate copper-zinc- ammonia complex (not yet identified) which is catalytically formed at the brass/solution interface and is surface active. It is suggested also that linear relationships like (a) and (b) above may be distinguishing features of stress corrosion cracking mechanisms which involve surface energy lowering.