ON DYNAMIC ISOMERISM. 135 
Dynamic Isomerism.—Report of the Committee, consisting of 
Professor H. BE. Armstrrone (Chairman), Dr. T. M. Lowry 
(Secretary), Professor SypNEy Younc, Dr. C. H. DkEscH, 
Dr. J. J. Dossiz, Dr. M. O. Forster, and Dr. A. Lap- 
worTH. (Drawn up by the Secretary.) 
Dynamic Isomerism in relation to Luminous Phenomena.* 
A. Absorption Spectra. 
Durina the past year two series of investigations on ‘ The Relationship 
between Absorption Spectra and Isomeric Change ’ have been completed 
and published.? Attention may now be directed to the decisive evidence 
adduced in these communications that the presence or absence of a 
band in the absorption spectrum of a camphor-derivative is in no way 
dependent on the occurrence or non-occurrence of isomeric change. 
(1) Nitrocamphor, which changes rapidly in neutral alcoholic solu- 
tions, does not give rise to an absorption band * even when the isomeric 
change is stimulated by the addition of an acid. Very strong bands are 
observed in the spectra of solutions of salts of nitrocamphor ; yet these 
salts are not known to exist in more than one form. 
(2) a-Chlorocamphor, on the other hand, which changes only in the 
presence of an alkali, exhibits a strong band in neutral and in alkaline 
solutions indifferently, the band being only slightly intensified by the 
addition of an alkali. 
(3) The B- sulphonates derived from a-chlorocamphor also undergo 
isomeric change only when an excess of alkali is added ; but this has the 
effect of weakening instead of intensifying, the absorption bands which 
are produced by neutral solutions of these salts. 
(4) In the case of the isomeric a- and #-bromo-derivatives of a 
methyl-camphor, it is found that the methyl-camphor band is not apparent 
k /CRCHs 
in the B-compound C,H),Br Sy , but is in the a-compound 
CO 
We Br.CH; 
C,H, Sas , in spite of the fact that the former contains a dis- 
placeable a-hydrogen atom, and that no such atom is present in the 
latter, which therefore is unable under any condition to undergo keto- 
enolic isomeric change. 
The decisive experiments that have been made with these optically- 
active substances have an important bearing on the general theory of the 
! The general discussion which follows is an amplification in the light of more 
recent evidence of considerations which were advanced by Armstrong in 1902 and by 
Armstrong and Lowry in 1903 (Proc. R.S., 72, 258-264) in a paper bearing these 
words as its sub-title. 
2 Trans. Chem. Soc., 1909, 95, 807-823; 1340-1346. 
’ The ‘shallow band’ referred to in the previous report was found to be merely a 
‘step-out,’ the effect of which had been exaggerated by under-exposure, 
