Invisible glass rod

This is very simple science experiment which can be done with ingredients available in the house. All we need is two glass beakers and a glass rod. Now we take water in one of the glass beakers. Now we will put the glass rod in it. Now we can see the glass rod in water. But it appears to be broken. The part which is seem to be broken, is when we see the glass rod inside water and not the part which is outside of water. Now what does it mean? When light passes through two different mediums, it bends when entering the other medium from one medium. In this case light passes through air to water and we feel that glass rod is bent inside water. This is refraction of light. Now we will take glycerin in another glass beaker and we will put the same glass rod which appeared to be broken ( but it wasn't ). Now we are surprised to see that glass rod which appeared to be broken in water now disappeared in glycerin !!! Now what does that mean? ????? ?????? It means light when travelled from air to glycerin didn't bend. Means refraction didn't take place. In other words, light felt no difference between the two mediums I.e. air and glycerin. LIGHT TRAVELLED STRAIGHT. That's why the part of glass rod which is inside glycerin APPEARS to be invisible.