Radicals, Reactions, Realism - Philosophy of Chemistry - page 185

radical, Gomberg postulated the following equilibrium (Cf. Gomberg 1928 ,
163, and Ihde 1967 , 7):

2 ¼

ð C 6 H 5 Þ 3 C 2C 6 H 5 ð Þ 3 C

As we have emphasized already, Gomberg s foremost approach to the characteri-

zation or proof of existence of his triphenylmethyl was based on reactivity . During
all these attempts he did not succeed in meeting the customary criteria like
those formulated at approximately the same time by Timmermans. Any of the
first three questions published by the latter must remain unanswered. However,
though the attempts to identify his solid and dissolved products ended up in more or
less plausible suggestions we can conclude that his empirical descriptions were
more than just lucky guesses. He not only found his own area of research and -
because he was a gifted, tenacious and prolific experimenter - owed his reputation
and fame; he also initiated an international research program which was devoted
to the search for stable free radicals.
Most speculative radicals of the nineteenth century, like benzoyl, cacodyl, ethyl
or acetyl (some of which later turned into formal-descriptive “rests” or “functional
groups”) had no chance to become real entities, or better, to be given an empirically
adequate description. 23 The Gomberg radical, in contrast, became more than just
some strange movement behind the curtain.
In the first place the reference to the concept of stuff is a macroscopic view, a
view very close to or rooted in the manifest world. 24 There are early attempts to
describe chemical substances and their changes without reference to a particle
picture but in an empiricist or operationalist attitude. Wilhelm Ostwald (1853-
1932) was among those who were skeptical of metaphysical assumptions in general
and with speculative atomism in particular. He claimed that a recognized chemical
substance must be capable of being isolated as a stuff sample. In his topic on
electrochemistry from 1896 he wrote:
It took a long time before it was finally recognized that the very nature of the organic
radicals is, inherently, such as to preclude the possibility of isolating them. And now it is
becoming evident that the same holds true of ions. 25

'

According to Ostwald, any metaphysical assumption about unobservable or
undetectable entities (atoms, molecules, ions, and radicals) should be avoided.

23

Here of course reference is made to Hacking ' s entity realism and van Fraassen ' s constructive
empiricism . We will return to both later. - It has to be noted that the mentioned ethyl radical - at
least what might be called its empirically adequate correlate - eventually came into life in the
1930s, when Friedrich Paneth and his co-workers arranged to have determined short-lived methyl
and ethyl radicals in ingenious experimental set-ups (Paneth and Lautsch 1930 ). This intriguing
story and its specific philosophical background will be discussed elsewhere.
24 Van Brakel stresses this classical empiricist claim in his textbook van Brakel 2000 .
25 In his survey, Gomberg, referring to the “uninterrupted progress” of fixed quadrivalence of
carbon, cites this passage (Gomberg 1932 , 443).