ABSORPTION SPECTRA. 379 
nation of Baly, Edwards, and Stewart.’ It is equally conceivable 
that the groups in the ortho position may approach each other 
to at least the same degree as in the para positions, while the 
maximum of their separation is less than that possible in the 
latter case. The average of the influence of the two substituted 
groups upon each other might be much greater when they are 
in the ortho positions. 
We are convinced that a reéxamination of the absorption 
spectra of some of the compounds, which Baly, Tuck, and Mars- 
den 7? cite to oppose the quinoid theory, will show that the 
great shift in the position of a band on the addition of alkali 
is impossible and that the apparent shift is really the destruction 
of one band and the formation of a new one, a process which 
takes place progressively as the concentration of the alkali 
is increased. 
Hantzsch and Voigt 1* in discussing the relations existing be- 
tween p-nitrophenol and nitrobarbituric acid, 
HO< NO: i eal ls cu. NO» 
have assumed that the great change in the absorption spectrum 
of the former and slight alteration that takes place in that of the 
latter in the presence of alkali did not vitiate the exact analogy 
between the two substances. The evidence that the band of 
p-nitrophenol salts is an entirely new band from that shown 
by p-nitrophenol itself, while the band of nitrobarbituric acid 
is actually shifted by alkali, would indicate that the benzene ring 
plays an important part in aci-conjugated nitro compounds rather 
than an unimportant role as these authors state; and that their 
analogy between these two compounds is therefore not justified. 
Since writing this article we have received the September 
issue of the Journal of the Chemical Society (London) and note 
the article by Hewitt, Pope, and Willett.* From their descrip- 
tion of the absorption spectra of p-nitrophenylacetonitrile and 
some related compounds, it is evident that the structure of these 
substances in alkaline solution is capable of the same explanation 
as that applied to nitrophenols. 
“Ibid., 524. 
“bid. (1910), 97, 571 and 1494. 
*% Ber. d. deutschen chem. Ges. (1912), 45, 103. 
“The absorption spectra of nitro compounds, Journ. Chem. Soc. London 
(1912), 101, 1770. 
