As deadly as it is beautiful, chlorine's characteristic yellow hue turns to a viscous, deep yellow-orange liquid when pressurized to over 1000(!) Psi, as in this little ampoule. If you were to heat this cube in boiling water (and, uh, we're not saying you should) you would cross the supercritical liquid-vapor point and the liquid would appear to vanish. After cooling down it would suddenly condense back out into a half and half state as in the photo. One of our most attractively displayed offerings.

This is a small ampule containing pressurized chlorine in gel revealing its intense yellow color.