  The analysis of multiple populations (MPs) in globular clusters, both
spectroscopically and photometrically, is key in understanding their formation
and evolution. The relatively narrow Johnson U, F336W, and Stromgren and Sloan
u filters have been crucial in exhibiting these MPs photometrically, but in
Paper I we showed that the broader Washington C filter can more efficiently
detect MPs in the test case globular cluster NGC 1851. In Paper I we also
detected a double MS that has not been detected in previous observations of NGC
1851. We now match this photometry to NGC 1851's published RGB abundances and
find the two RGB branches observed in C generally exhibit different abundance
characteristics in a variety of elements (e.g., Ba, Na, and O) and in CN band
strengths, but no single element can define the two RGB branches. However,
simultaneously considering [Ba/Fe] or CN strengths with either [Na/Fe], [O/Fe],
or CN strengths can separate the two photometric RGB branches into two distinct
abundance groups. Matches of NGC 1851's published SGB and HB abundances to the
Washington photometry shows consistent characterizations of the MPs, which can
be defined as an O-rich/N-normal population and an O-poor/N-rich population.
Photometric synthesis for both the Washington C filter and the F336W filter
finds that these abundance characteristics, with appropriate variations in He,
can reproduce for both filters the photometric observations in both the RGB and
the MS. This photometric synthesis also confirms the throughput advantages that
the C filter has in detecting MPs.
