the three-mile loop closed to tourists because extreme heat is causing thick oil to bubble to the surface. look at that. that's an oil slick. the world's tallest thermometer back on-line after two years of renovation. the 134 foot thermometer is in baker, california. it reached the highest official temperature on july 10, 1913 in death valley. >> what was the temperature? >> 113. >> next we're talking about a liquid crime fighting tool, very high tech that can be seen under a black light. it is like a scene out of a crime drama. crops in florida and indiana are using this high tech spray that's catching criminals in their tracks. i got a chance to check it out. >> oh man! >> just as fingerprinting and d.n.a. revolutionized