How to Make an invisible bottle - Disapparing glass in glycerin

The invisible bottle.

We need:
-glycerol,
-glass,
-empty bottle.

The experiment:
First We poured a glass of glycerine so it fills 1/3 of its volume.
Second Bottle filled with glycerine we put into a glass filled with glycerol.
Results:
When we put a bottle of glycerine in a glass bottle was submerged part invisible. This happened because the refractive indices are close to each other.