ON ABSORPTION SPECTRA OF ORGANIC COMPOUNDS. 301 



third atomic frequency series will converge at the frequency 2.344 xlO'% whilst 

 the second and third will converge at the frequency 1.918x10'=. These atomic 

 group or iiitra-molccular frequencies form the fir.st members of two new series 

 which converge at the molecular frequency 4.22x10'-'. It may be noted that 

 this molecular frequency lies in the short-wave Jnfra-red and corresponds to 

 the wave-length of 7.1/*. 



These relationships are exactly those which have been observed. The 

 complete structure of the absorption bands of SO2 and H2O, which is that 

 described above, was detailed in the last report of the Committee, together 

 with tho subsidiary frequencies which are associated with the molecular and 

 intra-moloculav frequencies to give broad absorption bands. No further dis- 

 cussion, therefore, is necessary. 



The two most important facts which must be emphasised are. fir.st, the 

 characterisation of a molecule by its own molecular quantum, and, second, the 

 possibility of a molecule gaining an amount of energy equal to its characteristic 

 quantum on exposure to radiation of frequencies equal to those of its atoms 

 or component groups of atoms. The molecular quantum is the most funda- 

 mentally important characteristic, since it not only determines the absorptive 

 power of a molecule in the visible and ultraviolet, but also forms the quantita- 

 tive basis of every chemical reaction which the molecule undergoes. The 

 importance of the molecular quantum will be understood from a consideration 

 of the affinity which causes atoms and molecules to react together. The first 

 assumption, which forms the basis of the present theory, states that the atomic 

 quantum is the amount of energy required to shift an" electron from one orbit 

 to another, the electrons being conceived as normally rotating in fixed orbits 

 round the central positive nucleus of the atom. This rotation of a negatively 

 charged particle will establish an electro-magnetic field, the force lines of which 

 pass through the plane of rotation. An atom, therefore, forms the centre of 

 a force field and will possess two faces, which may be called positive and 

 negative. If two atoms approach one another in such a way that their like 

 faces come together, they will repel one another, but if their unlike faces come ' 

 together they will attract one another. When this happens, energy will be 

 lost by the two atoms in the manner already described — that is to "say, each 

 atom will lose an amount of energy equal to the least common integral multiple 

 of the quanta of the two atoms. In common parlance the two atoms enter into 

 chemical combination, and in order to decompose the freshly synthesised mole- 

 cule an amount of energy will be required which is exactly equal to that lost — 

 namely, one molecular quantum. The combination of the two atoms was due 

 to the attraction between one face of each, and consequently there are yet to 

 be considered the two remaining faces of the atoms in the freshly synthesised 

 molecule. It is impossible tliat the force lines at tliese two faces, which are of 

 opposite type, can exist without mutual influence, and condensation must ensue 

 between these with the further escape of energy. A freshly synthesised mole- 

 cule, therefore, is metastable, since the external force fields of its atoms must 

 condense together to form a molecular force field. The loss of energy involved 

 in this condensation is a process in which the molecule as a whole takes part, 

 and consequently the energy can only be lost in terms of the molecular quantum. 

 A freshly synthesised molecule m.ust thus pass into one of a number of possible 

 phases, each consecutive phase differing in energy content by one molecular 

 quantum and also in the condition of its molecular force field. It is evident 

 that in this process the molecule will not suffer any loss of individuality as 

 far as its characteristic quanta are concerned. None of the deductions made 

 above will be contradicted, and the only change will be the endowment of the 

 system with an additional quantum, and therefore an additional frequency. 



Let the ternary molecule discussed above be again considered. If this mole- 

 rule when in the freshly s\'nthesised state absorb one molecular quantum of 

 2.772x10-" erg, it will just be resolved into its component atoms. If now, 

 after the formation of its molecular force field with the loss of one molecular 

 quantum, it is wished to resolve the molecule into its atoms, two quanta or 

 5.544x10-13 erg will be necessary. The molecule and its force field can absorb 

 these two quanta simultaneously, and therefore the system becomes endowed 

 with a new quantum which is twice the molecular quantum. In general, if the 

 molectile, during the formation of its force field, lose 1X2. 772x10-" erg, the 



