This study focuses on the French chemists of 1830-58, and their roles in the development of organic chemistry and its eventual connection with atomic and valence-bond theory, and uncovers new complexities in the thought processes that led to the concept of valence. The exploration of Laurent's early career reveals that this French chemist had proposed a hypothesis to explain phenomena due to valence fifteen years before August Kekule's exposition of his classic valence-bond theory in 1858. Laurent put forward a hypothesis supposing the divisibility of atoms at a time when such a theory was far removed from the possibility of experimentation. Within the positivist philosophy which prevailed at the time, few besides him would have dared to advance such a hypothesis. Laurent's ideas and those of his close associate, Charles Gerhardt, directly influenced the English chemist, Alexander Williamson, who in turn began a definitive shift towards atomism, a precondition of the eventual concept of valence. Laurent's and Gerhardt's unique systems of chemistry invoke parallels with the patterns of revolutionary science described by Thomas Kuhn. Novitski explores the process of interaction between the philosophical beliefs about science, and the actual practices of working scientists, providing insights into the personal and socio-economic milieu in which these chemists worked.