292 SECTIONAL TRANSACTIONS.—B. 
H H 
Cara 
hexadiene, HCY Ncu, produces no optical exaltation in the 
Ce 
H, Hy; 
visible spectrum, although the molecular refraction Mp of 2 : 4-hexadiene, 
CH; —CH =CH —CH =CH —CH,, is 1-65 units higher than that observed 
in diallyl, CH,=CH—CH,—CH,—CH=CHgz, where the two double 
bonds are isolated from one another by three single bonds. Exaltation is 
observed, however, at wave-lengths in the vicinity of a strong ultra-violet 
absorption band which is characteristic of the conjugated system. The 
magnitude of the optical exaltation will depend on the position and intensity 
of this absorption band, which may be influenced by many factors. It is 
suggested that one of these factors may be the relative orientation of the 
conjugated double bonds, which can take up a parallel configuration, 
\ 
C—C ,, in open-chain compounds, but are held in an inclined con- 
figuration, Ne de in ring compounds. 
AFTERNOON. 
Visit to Stoneywood Paper Works of Messrs. A. Pirie & Sons, Ltd. 
Friday, September 7. 
Discussion on Ascorbic acid (vitamin C) (10.0) :— 
Prof. A. Harpen, F.R.S.—History of vitamin C. 
It was recognised as early as 1734 that scurvy was due to the lack of fresh 
vegetable food and could be cured by the supply of this. In 1907 scurvy 
was ‘ brought into the laboratory’? by Holst and Frélich, who, using the 
guinea-pig, made a rough and mainly qualitative survey of the antiscorbutic 
potency of foodstuffs and studied the effects of heat and preservation on this 
property. Fiirst, in the same laboratory, also found that in leguminous seeds 
antiscorbutic potency arose during germination. Strictly quantitative obser- 
vations soon followed, first in England and then more generally, and it was 
found that the antiscorbutic vitamin, as it was now called, was very un- 
equally distributed among vegetables and fruits, etc. Studying the physical 
and chemical properties of the vitamin, Zilva, of the Lister Institute (1924 
and onwards), succeeded in concentrating it about 200 times and found that 
the preparations always had strong reducing properties. Removal of the 
reducing power by titration with indophenol did not inactivate the prepara- 
tion, but this soon became inactive on keeping. This behaviour was inter- 
preted as being due to the presence of a reducing principle which exerted 
a protective influence on the vitamin. In 1932 Tillmans and Hirsch con- 
firmed these facts, but showed that the oxidation by indophenol was 
reversible and that the facts were consistent with the conception that the 
vitamin itself had reducing properties. They further suggested that it 
might be identical with the strongly reducing hexuronic acid found in the 
adrenals and in many vegetable juices by Szent-Gyérgyi (1928). The 
discovery by the latter (1932) that this acid, henceforward to be known as 
