Book Reading Update - Fontana History of Chemistry Chap 6

I finished reading Chapter 6 which detailed the development, evolution, and partial merging of the two primary classifications of organic compounds conceived in the 1800's.  Berzelius and followers championed a dualistic theory of classification by radicals based on the idea that every organic compound can be thought of as a combination of an electropositive radical and oxygen. This definition could not be supported by observations of substitution reactions in which an electronegative element replaces electropositive hydrogen.  Dumas followed by Laurent, Williamson, and finally Gerhardt were the key players in developing and refining the classification by types, based on a unitary theory that suggested that compounds of the same chemical type share similar fundamental chemical properties and that chemical behavior can be ascribed to the arrangements of atoms.  Gerhardt, in his 'new tye" theory, eventually suggested that all organic compounds can be ultimately classified based on four inorganic basis or types: water, ammonia, hydrogen, and hydrogen chloride, with each type being conceived as 'the unit of comparison for all bodies which, like [them], are susceptible of similar changes or result from similar changes".  It was stated, however, in the end that this form of classification held no structural significance to Gerhardt but eventually the "new type theory metamorphosed in to the structural theory of carbon compounds" in the hands of Kekule et al.