  We propose that relativistic Galactic jets like those observed in GRS
1915+105 and GRO J1655-40 may produce small but measurable contributions to the
cosmic ray (CR) spectrum. If these jets contain cold protons and heavy ions (as
in SS433), it is plausible that this component will consist of a narrow
spectral feature, with a mean particle energy corresponding roughly to the bulk
kinetic particle energy in the beam, Gamma_jet m c^2, which, based on current
estimates of Gamma_jet, falls into the range of 3-10 GeV. The presence of
several sources with different Gamma_jet will lead to superposition of several
such peaks. Additionally, diffusive particle acceleration should produce a
powerlaw whose low energy cutoff at or above Gamma_jet^2 m c^2 would be visible
as another spectral feature. The large metallicities measured in several
microquasar companions suggest that this CR component could have an anomalous
composition compared to the bulk Galactic CRs. We provide estimates of the
effects of adiabatic losses, which pose the greatest challenge to models of
narrow band CR production in microquasar jets. While the total energy contained
in the microquasar CR component is highly uncertain, the CR spectrum in the
vicinity of microquasars would be severely affected. AMS02 will be able to
probe the low energy CR spectrum for such components and composition anomalies.
The spectrally peculiar gamma-ray emission produced by interaction of the ISM
with CRs surrounding microquasars might be detectable by GLAST. If the presence
of a microquasar CR proton component can be ruled out observationally, this
argument could be turned around in favor of electron-positron jets. We show
that existing OSSE/GRO and future INTEGRAL data on the Galactic 511 keV line
flux put interesting constraints on the particle content of microquasar jets.
