In a critical point dryer liquefied carbon dioxide is substituted for the water contained in a (typically biological) sample. When the liquefied carbon dioxide is allowed to transition to gaseous carbon dioxide, the “wet” (in liquid) sample instantly becomes a “dried” (in gas) sample. In this way the hydrated appearance of the structure is retained and stabilized for examination by scanning electron microscopy. (Image: Electron Microscopy Sciences, model EMS 850 critical point dryer).