Hey morb!
I believe that the flask has to do with the burning down of the BGW in the great Baltimore fire of 1850.The Phoenix is suppose to represent the rebirth through fire.I think the flask is called the "RESURGAM" flask,which means "I shall rise again".That's all I remember.
By the way,way cool find!
Hey Morb you have the GXIII-53 in your possesion.A nice flask,Mckearins lists it as common but the lip treatment on your is different then on most others.