[Thomas An.]

Micha,

I think you are right.
The cutout box has more color because additively the light goes through 2 glass walls, but in the enclosed volume it only goes through 1 glass wall (the inside voume is the liquid).

It seems to me that the Maxwell light calculation needs a little more complexity.... right now the ND and snell's law is tracked correctly, but Maxwell needs a better method of tracking color as it goes in and out of membranes.