We have here these two Petri dishes. In one of them I will pour water and in the other ethyl alcohol, also known as
ethanol. Just letting it drop flat, the blade
is kept on the water surface. Now we will try the same on ethanol … it sinks directly. I will try with more care. Nothing, the weak surface tension of alcohol
can not stand the blade. Now I am going to put some alcohol drops
in the water to see what happens. The blade sinks because the surface
tension is reduced.