‎"GERHARDT, CHARLES. - THE THEORY OF TYPES AND RADICALS.‎
‎Recherches sur les Acides organiques Anhydres. Presentées à l'Academie des Sciences, les 17 mai et 14 juin 1852.‎

‎Paris, Victor Masson, Imprimerie de Bachelier, 1853. 8vo. Contemp. hcalf, raised bands, gilt spine. Light wear along edges. Slightly rubbed. A small weakness to upper part of fronthinge. Small stamps on verso of titlepage and on verso of plates. In ""Annales de Chimie et de Physique"", 3me Series - Tome XXXVII. 512 pp. and 3 plates. (The entire volume offered). Gerhardt's paper: pp. 285-342. Light scattered brownspots.‎

Reference : 43123

‎First printing of an importent paper in which Gerhardt introduced the concept of ""type"" in organic chemistry in order to understand all substitution reactions.""Gerhardt adopted Laurent's nucleus, or unitary theory and combined it with the theory of types and radicals. In 1852 he discovered the anhydrides of organic acids and explained their structure by an extension of the water type of Williamson. He further proposed that all organic compounds could be related to one of four inorganic types: water, hydrogen, hydrogen chloride, and ammonia. These types could be used to explain most organic reactions as double decompositions. Since Gerhard felt that the formula of organic compounds never ecpressed the actual structure of the molecule, but only its reactions, he was satisfied with this theory and carried it no farther. However, it was a great advance in systematization and helped to bring order into the confused field of organic reactions.""(Leicester & Klickstein ""A Source Book in Chemistry 1400-1900"", p. 351.).""Gerhardt will occupy a permanent position in the history of Chemistry for his services to organic classification, for his concept of homology, for his preparation of acid anhydrides, and for his reform of equivalents.""(DSB V, p. 374).The volume contains further importent papers Marcelin Berthelot ""Sur la Bichlorhydrate D'Essence de Térébenthine"", pp. 223-230, by Arago, Edmond Becquerel etc.etc.‎