  The "spin-up" and "spin-down" projections of the second order, chiral form of
Dirac Theory are shown to fit a superposition of forms predicted in an earlier
classical, complex scalar gauge theory (April, 1992 Class. Quantum Grav.). In
some sense, it appears to be possible to view the two component Dirac spinor as
a single component, quaternionic, spacetime scalar. "Spin space"
transformations can be considered transformations of the internal quaternion
basis. Essentially, quaternionic Dirac Theory projects into the complex plane
neatly, where spin becomes related to the self-dual antisymmetric part of the
metric. The correct Dirac eigenvalues and well-behaved eigenfunctions project
intact into a pair of complex solutions for the scalar curvature in the earlier
theory's Weyl-Cartan type geometry. Some estimates are made for predicted,
interesting atomic and subatomic scale phenomena. A form of electromagnetic
quanta appears. A generalization of the complex geometric structure is then
sketched in an appendix that allows quaternionic gauges and curvatures, and has
some Weyl nonmetricity mixed with torsion. It appears to be a well defined
structure, and leads to the full, second order, quaternionic Dirac Equation
form, and a first order equation for a closely related, auxiliary wavefunction.
A family of "free particle" solutions is examined in the Lorentzian limit of
the symmetric part of the metric. More generally, when limited to two
quaternion dimensions (just two components), reasonably similar solutions can
be superposed linearly into new solutions, and separate into two families with
different commutation characteristics. The integrability conditions for the
equation for the auxiliary wavefunction impose six conditions on the original
wavefunction, satisfied for the "free particle" solutions examined. Covariance
is examined. The Darwin solution for the hydrogen atom is examined.
