Pyrex flask model. To save some rendering time I set up 'fake' caustics' using a projection map on the spotligt that is directly above the flask. This has a gradient map with noise turned on. This can be edited by going to the material editor and going to the material named 'light map'. If you want to do it correctly using mental ray, you may want to turn off this projection map in the spotlight. The flask is also part of a collection of lab equipment on Turbosquid. You can find it by searching for Simplicity3d. It is part of the Liebig condenser scene.