The Spread of Williamsonian Theory

Gerhardt was thrilled by Williamson s first ether paper (Laurent was already mortally ill and could not participate fully in these developments). Over the next six years he combined Williamson s new reactions with those of Adolphe Wurtz, the chemistry professor at the Faculty de M decine in Paris, and those of August Wilhelm Hofmann, the director of the Royal College of Chemistry in London, to outline a new version of type theory. In Gerhardt s telling, Williamson s work had given birth to a water type, Wurtz s and Hofmann s efforts had ere- 

The theoretical ground in European chemistry began perceptibly to 

Soon thereafter, Kolbe s comrade-in-arms, Frankland, submitted for publication a landmark paper that, similar to Brodie s and Hofmann s work, pointed toward serious anomalies in the copula theory. As a master (indeed, the founder) of organometallic chemistry, Frankland adduced examples of reactions that indicated that tin, zinc, mercury, antimony, arsenic, phosphorus, and nitrogen exhibit fixed maximum combining capacities with other atoms or radicals. Arsenic and antimony, for instance, seem to combine only with three or with five equivalents of other atoms or radicals. If the maximum capacity is reached, then only substitution, not addition, of other components can occur. Frankland had turned he now allied himself with the ammonia type theory of Hofmann and Wurtz, for the semimetals antimony and arsenic seemed to follow exactly the pattern established by the new organic nitrogen compounds of the latter chemists. The theory of copulas, he declared, could no longer be maintained.  

There appears to be much in common between these statements and Williamson s avowal a year earlier that certain radicals and atoms are bibasic and can suffer substitution but not addition reactions. Both claims have legitimately been interpreted as early approaches to what came to be known as the theory of atomic valence. (Frankland s had 

For a vigorous and thoughtful championing of Frankland s undiluted claim to valence theory, see Russell, Frankland. 

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