The properties of these two substances are so different i.e. mercury has a density of 13.4 times that of water.  What is so unusual is that the viscosity of mercury is so low, only slightly more viscous than water.  By adding food coloring we can study the interaction, air bubbles and weirdness better.  Basically a lot of air bubbles form as the mercury travels through the corn syrup to the bottom of the glass.  Looks pretty gnarly.  Thanks for watching.