It was Andrea Appiani's Napoleon at Lodi's Bridge, c1800 that was so interesting. There are several of Appiani's works throughout the museum, including the magnificent fresco painted in 1811.
The painting itself is very stylised, painted in grey tones. Given that, there is not a lot you can get regarding uniform colours, but what really interested me was that this painting, which was painted in 1800 only four years after the battle, showed French infantry wearing helmets!
Given the style of the painting I'm not sure if this can be used as a reference to the wearing of helmets at this time, but Napoleons uniform certainly looks correct.