An infrared cell is described which extends the range of temperatures for liquids up to the critical temperature. Window materials are sapphire or calcium fluoride, sealed to the cell walls by teflon O-rings. Brass may be used for the cell body, but alloys of low thermal expansion are preferable. Thermal expansion of the cell prevents accurate determination of intensities. The cell performed well enough to yield the spectrum of liquid water and alcohol solutions up to the critical points.
E. Fishman, "A Very High Temperature Infrared Cell for Pure Liquids or Solutions," Appl. Opt. 1, 493-495 (1962)