Bushwhacker + Floater

   Today we went up to Moe's BBQ to have a Bushwhacker. If you don't know, a Bushwhacker is sort of like a Mudslide, but with spiced rum and, for $2 extra, a "floater" of Bacardi 151 drizzled on top. However, Moe's takes the floater to the next level by giving you a test tube of Bacardi inverted in your drink. Thanks to my education, my alcoholic beverage has turned into a science experiment.
   Assuming the floater to be completely full at the start, naturally some was spilled during the inversion process, leading to the air-filled region pictured in the test tube. The rest of the Bacardi remains inside the test tube, suspended by the atmospheric pressure pressing down on the surface of the drink.

After drinking half of the drink, (most) of the alcohol remained suspended in the tube. I did notice the presence of very small bubbles moving up in the tube, most likely due to some mixing at the interface of the straight alcohol and the beverage. However, the volume of alcohol in the tube remained unchanged due to the constant pressure on the surface of the drink.

 

Pulling the tube up out of the drink caused no change in the volume inside the tube. Residue on the outside of the tube can be seen, but the outside of the tube remained (visually) pure.