There are 17 conditions associated with discharge or mucus in eyes, drainage or pus and yellow eyes. The links below will provide you with more detailed information on these medical conditions from the WebMD Symptom Checker and help provide a better understanding of causes and treatment of these related conditions.
Burning glass. A burning glass or burning lens is a large convex lens that can concentrate the sun's rays onto a small area, heating up the area and thus resulting in ignition of the exposed surface. Burning mirrors achieve a similar effect by using reflecting surfaces to focus the light.
Sand will not burn. Sand can be turned to a glass like substance on heating to very high temperature. Yes, this is true. Certain types of sand have high levels of silica in them, and when it is heated, the silica sand melts, and becomes the liquid substance that will cool, harden, and become glass.