4) The 0 (zero) positions of C## and Dbb are without polarity (i.e., depolar) therefore do not have a positive and negative oscillation (tone). The Inert or Noble gases reside at the 0 (zero) locations or very close thereto. Russell says of this "The Inert Gases are not elements and are therefore toneless and colorless." The Universal One, page 249. However, we know from modern chemistry these elements are not perfectly neutral and do combine with other elements under certain conditions.
5) In Figure 11.01 - Octave composed of Equal Thirds and Triads we see the Fifth has its arithmetical root in the next lower octave.
NOTE: C## and Dbb are essentially the same being octaves of each other.
6) G is the average/mean of these two as also the sum of the two lower octaves:
|(512 + 1024)/2||=||768|
256 + 512
See Russell, The Universal One, pages 9, 11 and 249