‎"FRANKLAND, E. (EDWARD). - INTRODUCING ""VALENCY"" IN CHEMISTRY.‎
‎On a New Series of Organic Bodies containing Metals. Received May 10,- Read June 17,1852.‎

‎London, Richard Taylor and William Francis, 1852 4to. No wrappers as extracted from ""Philosophical Transactions"" 1852 - Part II. With titlepage to Part II., pp. 417-444, textillustr. Fine and clean.‎

Reference : 42941

‎First appearance of an extremely importent paper in the histroy of chemistry as Frankland here introduced the concept of 'VALENCY' - he called it 'atomicity' - to explain the capacity of atoms to combine with other atoms. ""This led not only to the Kekulé structures, but also to the periodic table of Mendeléev, since that table was based on the regular change of valence with atomic weight.""(Asimov).""On May 10 1852 Frankland read to the Royal Society a paper on organic metallic compounds (the paper offered) in which he made the emperical observation that elements possessed fixed combining powers, or ""only room, so to speak, for the attachement of a fixed and definite number of the atoms of other elements."" The expression ""valence"" or ""Valency"" began to be used by other chemists only after 1865, wheras Frankland tended to use the misleading term ""atomicity""....Frankland's teching position at the Royal College of Chemistry and his influence on the Department of Sciences and Art science examinations enembled him to spread the idea through the younger generation of British chemists.""(DSB V, p. 126).The exact inception, however, of the theory of chemical valencies can be traced to an 1852 paper by Edward Frankland, in which he combined the older theories of free radicals and ""type theory"" with thoughts on chemical affinity to show that certain elements have the tendency to combine with other elements to form compounds containing 3, i.e. in the three atom groups (e.g. NO3, NH3, NI3, etc.) or 5, i.e. in the five atom groups (e.g. NO5, NH4O, PO5, etc.), equivalents of the attached elements. It is in this manner, according to Frankland, that their affinities are best satisfied. (Wikepedia).‎