180 INORGANIC EVOLUTION. [CHAP. 



results obtained by chemists we cannot be dealing with a mixture of 

 molecules, the fluting absorption therefore must be produced by mole- 

 cules of one complexity having an " atomic weight " of 16. 



If we subject it to an induced current at low pressure (at which 

 the action of such a current is feeblest), it at once breaks up into two 

 normal sets of three series, that is six series altogether ; it is almost 

 impossible to consider this state of things in the light of what happens 

 in the case of sodium and hydrogen without assuming on the ordinary 

 chemical view that the " molecule " with the fluted spectrum is broken 

 up into two, until finally we get 



High temperature. 



SET A. SET B. 



f Principal series. Principal series. 



Line spectrum ..^Subordinate. Subordinate. 



^Subordinate. Subordinate. 



Fluted spectrum. 

 Low temperature. 



But if we accept this, we give up depolymerisation, for the mole- 

 cules of the subordinate series of sets A and B thus produced cannot 

 be identical, because their spectra are not identical. 



If we hold to depolymerisation we must arrange matters thus 



(^Principal. 



I 

 Set B or A . . \ Subordinate. 



I 

 ^Subordinate. 



fPrincipal, 



I 

 Set A or B . . { Subordinate. 



^Subordinate. 



Fluted spectrum, 

 and we get six depolymerisations. 



The number of lines measured by Runge and Paschen in the spec- 

 trum of oxygen at low temperature was 76 ; of these the six series 

 referred to contain 56, leaving 20 residual lines. Now if we employ a 

 strong induced current at atmospheric pressure, we practically extin- 

 guish these six series of lines and produce a new spectrum altogether, 

 containing a still greater number of lines : 114, according to Neovius. 

 Only one line is common to his table and that of Runge and Paschen. 

 About the series conditioning of these new lines we are at present 

 profoundly ignorant. 



