ON ABSORPTION SPECTRA ANt) CHEMICAL CONSTITUTION. 107 



Paet II. — On the Curves of Molecular Vibrations of Quinone^ 

 Tp- If^itroso-jjhenol, and similarly derived Stibstances. 



The absorption spectra of quinone, j;-nitroso-phenol (quinouoxime), have 

 recently been investigated by Messrs. Hartley, Dobbie, and Lauder, not 

 only with a view to obtaining information on the subject of the consti- 

 tution of these substances as represented by tlie different formulse which 

 have been proposed for them, but also to determine whether there was any 

 special character in the absorption curves of substances of the quinone 

 type common to and distinctive of all coloured substances and dyes, 

 which could be conceived to be connected with some peculiarity in their 

 structure. There are some features which the three absorption curves of 

 quinone, jo-nitroso-phenol, and quinone dioxime show in common, and 

 jj-nitroso-phenol appeal's to stand in an intermediate position between the 

 other two. It may be the case that in a substance with such a constitution 

 as that represented by the following formula the oxygen is so condensed 







II 



/^\ 

 HC CH 



II II 



HC CH 



\c/ 



in the molecule that it forms a new kind of ring which possesses special 

 absorption properties resembling a modification of the benzene nucleus, but 

 differing chiefly in the greatly increased intensity of the absorption. 



If such a structural constitution is a reality the facts in support of it 

 have yet to be discovered. On the other hand, the formulae for quinone 

 may very well be written in a manner similar to that of ozone, a substance 

 which gives both a general and a selective absorption of a powerful 

 character, and which possesses a deep blue colour. If one atom of oxygen 



in ozone (\___\ be replaced by the benzene residue C^H^ we have 

 quinone as represented according to the peroxide formula 



CoH / I 

 ^O 



In point of fact the peculiarity of the quinone absorption curve is that 

 it contains two broad absorption bands shown at different stages of 

 dilution, and if we compare the curve of phenol with that of quinone, and 

 also with the absorption spectrum of ozone, we perceive how the atoms of 

 oxygen have modified the spectrum of the pheaol. There is this much of 

 similarity between them, that if we can suppose benzene and ozone to be 

 exerting a mutual action on their molecular and intramolecular vibrations, 



