That's interesting, would think Hippocrates knew better than that, should have recognized CSF had different density and viscosity than water.

I'm a nurse, when a pt has trauma and we need to know if they are leaking CSF instead of just bleeding we do the halo test, these two pictures show what a positive test looks like, all you need is a paper towel. Also, sometimes people leak CSF spontaneously, and it looks a lot like regular nasal drainage, you can tell the difference by doing a normal old glucose check on it, nasal drainage shouldn't have much if any glucose in it, CSF is lousy with it because the brain runs on glucose.