Theory of types

Dumas, J. (1840). Uber das Gesetz der Substitutionen und die Theorie der Typen [About the Law of Substitutions and the Theory of Types]. der Chemie undPharmacie, S3(3), 259. 

Jean Baptiste-Andr Dumas, 1800-1884. Professor of chemistry at the Athenaeum and at the Sorbonne. He devised a method of determining vapor density, and developed the theory of types m organic chemistry, which he defended against Berzelius duahstic electrochemical theory. From a study of the aliphatic alcohols, Dumas and Pehgot developed the conception of homologous series, See also ref. (62). 

In the theory of types, we owe to M. Dumas an idea which has already been the vehicle of many an important discovery in science, and which is undoubtedly destined to receive still more general application. 

The middle illustration depicts the other stream of thought, the theory of types, advanced initially by Dumas, in which compounds are related to a Chem ical Type (or Class). Classes make sense. Acids, which share H in common, com ... 

Laurent abandoned all emphasis on electrical forces. He believed that an organic molecule had a nucleus (which might be a single atom) to which different radicals might be attached. Organic molecules might then be grouped into families or types (hence, the theory of types). All the members of one type would have an identical nucleus to which any of a series of similar radicals could be attached and within the radicals there would be considerable room for variation. 

The theory of types impressed some chemists with the point that the oxygen atom consistently combined with two other atoms or radicals. It might combine with two hydrogen atoms to form water. 

Dumas published four other memoirs on the theory of types which will be referred to in appropriate places. Dumas and Stas record the first use of potash-lime , the precursor of soda-lime, an invaluable reagent in organic chemistry. They point out the relation between amyl alcohol and valeric acid and between ordinary alcohol and acetic acid. By the action of alkali (heating an acetate with potash-lime) acetic acid forms marsh gas and carbonic acid ... 

Berzelius thought the theory of substitution and the theory of types are true for some cases but false for others. Of Dumas mechanical types he says that if carbon chloride, C CFCl (CCI4) may be. formed by substitution from methyl oxide, C OH , there is no reason why the carbon should not be substituted to form CPCPCl , or in other words, methyl oxide gas in which all the elements are replaced by chlorine. ... 

In 1842 Laurent, under the title Trent et unieme memoire sur les types , published an account of further researches on naphthalene derivatives. He gives a history of the theory of types (see p. 392) and describes, with their crystalline forms, the chloro-, bromo-, nitro-, etc., derivatives of naphthalene, the compounds formed by the action of nitric acid on the chlorides, chloroxy-naphthalic acid, chloroxynaphthose, etc. (now regarded as derivatives of... 

This Stir in the Academy aroused interest, and Quesneville devoted 171 pages of the first number of his new journal to disquisitions by Baudrimont, Couerbe, Dumas, Laurent, and Pelouze on their respective claims." Dumas had then published three memoirs on the theory of types and Laurent, who now began to publish in the Revue Scientifique, put out a memoir with a challenging title. In a later historical account of the theory of substitution,... 

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