What is water glass?

Water glass is

Water glass is:

Water glass is:

Water glass is :

Water glass is :

Water glass is :

The refractive indices of glass and water are 1.54 and 1.33 respectively. What is the polarising angle for a beam of light going from water to glass ?

The refractive indices of water and glass are 1.2 and 1.5 respectively. What will be the refractive index of glass with respect to water ?