THE COEFFICIENT OF OPACITY 
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can be given. Other sources of opacity have been examined without 
success. The field of inquiry is narrowed down to sources of emission of 
frequency between 2-5 RT/h and lRT/h. By assuming that the stars 
contain a large proportion of hydrogen the discrepancy would be removed; 
but this hypothesis would be in disagreement with earlier conclusions as 
to the intensity of radiation pressure. Other changes of chemical constitu 
tion make no important difference. 
At present the only suggestion of a possible reconciliation lies in the 
mysterious emission of Kulenkampff’s spectrum B, which is not accounted 
for by Kramers’ theory. We may also await developments of the new 
quantum mechanics of Heisenberg.