What are the optical properties of dog spittle?

Thanks for this. I'm sure the bubbles in the spit are acting as lenses and will investigate further ( when back from holiday ). Your details are excellent and I can hardly wait for a sunny day ( mid-winter here ) and a frothy bowl of detergent . I wonder if the sharpness of the pin points depend on the depth of water and the radius of the bubbles.... this is going to be good.