Manchester Memoirs, Vol. Iviii. (19 14), No. 15- 



XV. Quantitative Absorption Spectra, Part I. The 

 chemical significance of absorption spectra and 

 the methods of examining them. 



By Frkdekick Russell Lankshear, 



B.A.(N.Z.), M.Sc.(Vict.). 



Read May 12th, igi4. Received for publicalion Septembej- igth., igi4. 



Of recent years much attention has been given to the 

 study of the relation between the physical properties and 

 the chemical constitution of organic compounds. As a 

 result, knowledge of the internal structure of the molecule 

 has been greatly advanced. Not only have the relative 

 positions of the atoms in the molecule been more precisely 

 determined, but deductions have begun to be drawn from 

 experimental facts as to the nature of the forces which 

 hold atoms together in a state of combination. No 

 branch of this subject would seem bigger with possibilities 

 than the study of colour. Colour, whether in the ultra- 

 violet or visible regions, can easily be examined by means 

 of a spectrograph, it is a very characteristic property, in 

 many cases it is clearly allied to a definite structure, as in 

 the case of the a-diketones, and yet it must be confessed 

 that the results of the past thirty years' work have been 

 disappointing. It is true that the theory concerning 

 visible colour put forward by Witt and elaborated by 

 Hantzsch, Kauffmann and others is applicable to a wide 

 range of substances including the dyestuffs, but it is 

 rather a coordinated summary of observed facts than an 

 explanation of the origin of colour. In the field of ultra- 

 violet colour, the work of Hartley, Baly, Hantzsch and 



Octok'?- i6th, igr4. 



