Liquid Gold,

flowing out of a wall and down a drain,

 it looks like gold, 

 feels like gold,

is heavy like gold,

  so it must be brass! 

 Brazilian artist Vanderlei Lopes creates temporary interventions where his polished brass objects appear to pour and drain like gold from the walls or floors of galleries,

 You can see much more of his work on Artsy and Athena Contemporânea, for a few seconds they certainly had me fooled, pouring gold down a drain indeed!