The International Union of Pure and Applied Chemistry early recognized the need to establish international standards for chemical units, symbols and terminology. The overall responsibility for this program was vested in its Commission I.1 on physicochemical symbols, terminology and units. The more specific responsibility for spectroscopy was delegated to IUPAC Commission I.5 on molecular structure and spectroscopy. Other Commissions dealt similarly with colloids and surface properties, rheology, heterogeneous catalysis, electrochemistry, thermodynamics and kinetics. Through the 1950s and 1960s these separate Commissions produced their own documents. Though these were vetted before publication by the over-riding Commission 1.1, it was difficult to coordinate the practices of the different subject fields of chemistry. A first attempt by Commission 1.1 to provide a self-consistant set of symbols, units and nomenclature for all physical chemistry was undertaken by M.L. McGlashan in 1969. A revision was prepared by M.A. Paul in 1973 and published as a separate manual by Butterworth in 1975. A third edition by D.H. Whiffen came out in 1979. Subsequently a number of appendices were published in Pure and Applied Chemistry. The present volume is more than an updating of the previous editions. It differs both in concept and content from its forebears. With no intent to disparage the earlier volumes, this reviewer can truthfully state that possession of one of the earlier versions should not be pleaded as a viable excuse for not acquiring the newer text.
In the earlier editions, with laudable intent, attempts were made by Commission I.1 to make overriding decisions where it was a common practice to use different names or symbols for a given quantity in different branches of chemistry. Thus, for example, we find there was much variance in the specific definitions of such terms as "absorbance", "absorptance" and "extinction" and the precise use of p of CJ for wavenumber. The