Aviation Animation - Steep Spiral

FUN PREFLIGHT TRIVIA
Suppose your plane burns 100LL but you suspect maybe jet-A contamination. Fuel looks blue but something seems a little off. What is a simple test to tell in 30 seconds with no special equipment?  ANSWER: Pour a little of the suspect fuel on paper. Chart paper, note paper, any paper. If it is pure avgas withon 30 seconds it will all evaporate and there will be no trace of the event. If any Jet-A is in the mixture it will leave an oily spot visible.