Interesting experiments on this channel: making a flame that absorbs (sodium) light and viewing supercritical CO2:   #physics 
<br /><a href='https://www.youtube.com/watch?v=1o8ktldjcog
'>https://www.youtube.com/watch?v=1o8ktldjcog
</a><br /><a href='https://www.youtube.com/watch?v=J_vXK9uvRf4'>https://www.youtube.com/watch?v=J_vXK9uvRf4</a>