‎"GERHARDT, CHARLES. - THE ""LADDER OF COMBUSTION"" AND ""HOMOLOGOUS SERIES"".‎
‎Considerations sur les équivalents de quelques corps simples et composés. (2 Parts). + Recherches sur la salicine.‎

‎Paris, Victor Masson et Cie, 1843. No wrappers. In: ""Annales de Chimie et de Physique, Par MM. Gay-Lussac et Arago."", 3e Series, tome 7, Fevrier- issue and tome 8 Juin-issue. Entire issues offered. Pp. 129-256 and pp. 129-256. Cerhardt's papers: pp. 129-143 a. pp. 238-245. The salicine-paper: pp. 215-229 (tome 7). With halftitlepages to vol. 7 and 8.‎

Reference : 45009

‎First appearance of Gerhardt's first papers on the new concept of ""homology"", perhaps his most notable contribution to organic chemistry.""Gerhardt’s most conspicuous contribution to the developemfent of organic chemistry was his homologous series. His earliest publications were characterized by attempts to arrange organic compounds in series of increasing complexity: his ""ladder of combustion,"" rising from water and carbon dioxide at the foot to albumin and fibrin at the summit, was analogue of the biologists’ ladder of nature, another biological analogy was to underlie the application of his homologous series when they were refined in 1843: Gerhardt presupposed a principle of plenitude in organic chemistry which dictated that hitherto undocumented members of any series must exist. In addition, the concept of homology itself was of biological origin, deriving from Cuvier. For Gerhardt, however, it did not carry that structural connotation which it had for Cuvier. On this subject Gerhardt, simply asserted: ""We call substances homologues when they exhibit the same chemical properties and when there are analogies in the relative proportions of their elements."" (DSB). ‎