Paper b315262f
Video clip 2 - Critical opalescence
Here we see inside the autoclave whilst the temperature and pressure are above the critical values for CO2. As the footage progresses, the pressure of the CO2 is getting lower and approches the critical pressure. At the critical point, there is a change from a rippling transparent mist to a black mist. This is attributed to critical opalescence.
Please note that due to our lighting conditions the carbon dioxide undergoing critical opalescence in our footage may seem to be a black colour. This is not the case, and is an artifact of our front-lit light source. If our autoclave was completely transparent and lit from behind, critical opalescence of that substance would manifest as a white, bubbling effect.