detail making it difficult for any opponent to break him down, and in Robert
Le Rossignol he had the ideal experimental partner.
15 Indeed, the stamp of
Robert Le Rossignol, ‘professional chemist’, should have been writ large on
the work presented by Haber that day because the two men had laboured for
months on the revised investigation and had submitted (29 April 1907) a
substantial paper
16 to the Bunsen Society shortly before the meeting began.
But the transcript of Haber’s subsequent ’presentation’
17 shows that it was
curiously defensive and not at all representative of the careful work done by
the two men. So we firstly ‘reprise’ this paper because what Haber was able to
convey in response to Nernst on that day—and subsequently reported in
several biographies
18
—did both himself and Le Rossignol an historic justice.
5.3.1 On the Ammonia Equilibrium
Their paper began by describing ‘Die älteren Versuche’, the ‘older experiments’ conducted with van Oordt, and they immediately withdrew the
(frankly quite indefensible
19
) value of 0.012% equilibrium proportion of
ammonia at 1293 K. This value, they felt, may have arisen either because of a
special effect of the iron catalyst when fresh (i.e., the presence of nitride) or
because during the decomposition of the ammonia, insufficient time had been
allowed to permit the equilibrium position to be reached, resulting in the
presence of a higher percentage of residual ammonia than should otherwise
have been the case.
20 Overall however, Haber and Robert declared themselves
‘content’ with the basic design of the van Oordt experiments (Chap. 2). Their
new investigation therefore proceeded along the same lines as before but with
refinements that established the reproducibility of their results which in turn,
they maintained, showed that they must represent the true equilibrium
position.
The design of the Haber-Le Rossignol experiment was more robust than
Nernst’s, examining as it did the equilibrium from the decomposition and the
‘development’ (or synthesis) sides and the whole process involved a considerable range of practical skills practised entirely by Robert. Measured volumes
of dry ammonia at atmospheric pressure were passed over different catalysts at
temperatures between 1000 and 700 °C. Unchanged ammonia was ‘washed
out’, the product gases
21 dried then passed over a second share of the same
catalysts. The newly formed ammonia was again ‘washed out’ and both
washings determined volumetrically. In their paper Haber and Robert presented a table containing the results of 49 separate attempts at six different
temperatures. Their description of the experimental setup and preliminary
5 Hamburg, 12 May 1907
115
Le Rossignol he had the ideal experimental partner.
15 Indeed, the stamp of
Robert Le Rossignol, ‘professional chemist’, should have been writ large on
the work presented by Haber that day because the two men had laboured for
months on the revised investigation and had submitted (29 April 1907) a
substantial paper
16 to the Bunsen Society shortly before the meeting began.
But the transcript of Haber’s subsequent ’presentation’
17 shows that it was
curiously defensive and not at all representative of the careful work done by
the two men. So we firstly ‘reprise’ this paper because what Haber was able to
convey in response to Nernst on that day—and subsequently reported in
several biographies
18
—did both himself and Le Rossignol an historic justice.
5.3.1 On the Ammonia Equilibrium
Their paper began by describing ‘Die älteren Versuche’, the ‘older experiments’ conducted with van Oordt, and they immediately withdrew the
(frankly quite indefensible
19
) value of 0.012% equilibrium proportion of
ammonia at 1293 K. This value, they felt, may have arisen either because of a
special effect of the iron catalyst when fresh (i.e., the presence of nitride) or
because during the decomposition of the ammonia, insufficient time had been
allowed to permit the equilibrium position to be reached, resulting in the
presence of a higher percentage of residual ammonia than should otherwise
have been the case.
20 Overall however, Haber and Robert declared themselves
‘content’ with the basic design of the van Oordt experiments (Chap. 2). Their
new investigation therefore proceeded along the same lines as before but with
refinements that established the reproducibility of their results which in turn,
they maintained, showed that they must represent the true equilibrium
position.
The design of the Haber-Le Rossignol experiment was more robust than
Nernst’s, examining as it did the equilibrium from the decomposition and the
‘development’ (or synthesis) sides and the whole process involved a considerable range of practical skills practised entirely by Robert. Measured volumes
of dry ammonia at atmospheric pressure were passed over different catalysts at
temperatures between 1000 and 700 °C. Unchanged ammonia was ‘washed
out’, the product gases
21 dried then passed over a second share of the same
catalysts. The newly formed ammonia was again ‘washed out’ and both
washings determined volumetrically. In their paper Haber and Robert presented a table containing the results of 49 separate attempts at six different
temperatures. Their description of the experimental setup and preliminary
5 Hamburg, 12 May 1907
115