What is the critical angle for vegetable oil and water and plexiglass

Snell's law describes the relationship between the angles of incidence and refraction.

n1*sin (theta1) = n2*sin (theta2)

When light travels from a medium with a higher refractive index to one with a lower refractive index, a phenomenon known as total internal reflection occurs. The largest possible angle of incidence which still results in a refracted ray is called the critical angle; in this case the refracted ray travels along the boundary between the two media.

theta (crit) = arcsin (n2/n1) where n1>n2.

Assuming light enters the following media and refracts to the air (n=1):

For acrylic: n=1.590, theta (crit) = arcsin (1/1.490) = 42.4 degrees

For water: n=1.333, theta (crit) = arcsin (1/1.333) = 48.6 degrees

For vegetable oil: n=?