Xanthippa's Chamberpot

Shamelessly lifted from reddit:

A physicist, a biologist, and a chemist all go to the beach for their first time.

The physicists marvels at the waves, and wants to study the fluid dynamics. So he walks into the ocean to study them more closely, and obviously drowns.

The biologist wants to study the flora and fauna of the ocean, so he walks into the ocean as well and obviously drowns.

The chemist pulls out a notebook, and writes, “Both the physicist and biologist were soluble in water.”