From Osher Doctorow

The electrostatic Coulomb equation is:

1) F = q1q2/[epsilon r^2]

where epsilon is permittivity, having dimensions:

2) [epsilon] = M^(-1)L^(-3)T^2 Q^2

But the Skewon field is a particular kind of permeability/permittivity
of spacetime which can couple to gravity and is of premetric nature.

See "On the theory of the skewon field: from electrodynamics to
gravity," F. W. Hehl, Yu. N. Obukhov, G. F. Rubilar, M. Blagojevic
(respectively U. Cologne/Koln Germany, U Missouri-Columbia USA, Moscow
State U., U. de Concepcion Chile, U. Ljubljana Slovenia and Institute
of Physics Belgrade Serbia, arXiv: gr-qc/0506042 v1 7 Jun 2005, 15
pages.

Although there are only 3 papers in arXiv on the Skewon (2002, 2004,
2005), the keywords "gravity electromagnetic" yield 12 papers in arXiv
most of which have similarities to the Skewon ideas (including 2 in
2007). In addition, the 2nd of the 3 papers on the Skewon, by F. W.
Hehl, Y. N. Obukhov, and G. F. Rubilar is also in Phys. Rev. D70
(2004) 125015. Tracing the publications histories of the authors via
arXiv yields a substantial additional source of similar papers.

The June 2005 paper cited two paragraphs above involves metric-
independent electrodynamics or laws of conservation that can be
formulated as metric-independent electrodynamics but generally
covariant in the spirit of Cartan and a number of more recent
researchers.

Osher Doctorow