Haughton — Notes on Newtonian Chemistry. 
645 
Fig. 6. 
In Pigure (6) I have exhibited the general form of equation 
(sy 
regarded as a curve showing the relation between atomic weight and 
periodic time of molecular rotation. 
All to the right of the line mOm is real and corresponds to positive 
values of atomic weight, and all to the left of mOm is unreal and cor- 
responds to negative values of atomic weight ("behind the looking- 
glass"). 
The curve has one real asymptote shown by the line A A, and two 
branches, one to the right which is real and hyperbolic, and one to the 
left which is unreal and nodal. 
The real elements represented on the hyperbolic branch are 
hydrogen, fluorine, chlorine, bromine, and iodine ; and hydrogen lies 
at the opposite side of the line pOp, because its rotation is opposite to 
that of the other named elements. 
It is a remarkable fact that no portion whatever, real or unreal, 
of the curve, exists in the shaded space between the lines mOm and 
