In thermodynamics, Charles Cagniard de la Tour (1777-1859), or Charles Cagniard-Latour, was a French engineer and physicist noted for his 1822 experiments with the Papin digester wherein he discovered the concept of critical point, the idea that a gas does not liquefy when compressed unless its temperature is below a certain critical value, called the critical temperature. [1]
In 1822, Cagniard discovered the existence of water's critical point—that is, the temperature and pressure at which the distinction between water's liquid and gaseous states disappears. His experiment was simple and ingenious.
Cagniard partially filled a steam digester with water and then added a flint ball. By rolling the digester like a log, he sent the ball in and out of the liquid, creating a splashing sound that he could hear. When the digester reached 362°C, not far from the true value of 374°C, the liquid–gas interface disappeared and the splashing stopped. The fluid in the digester had become supercritical. [2]
Other
Cagniard was a friend of French physicist Joseph Gay-Lussac. [3]
References
1. Shachtman, Tom. (1999). Absolute Zero and the Quest for Absolute Cold (Charles Cagniard de la Tour, pg. 67). Mariner Books.
2. Day, Charles. (2011). “The Ingenuity of Experimenters”, PhysicsToday.org, Apr 19.
3. Kondepudi, Dilip K. (2008). Introduction to Modern Thermodynamics (pg. 20). John Wiley and Sons.
External links
● Charles Cagniard de la Tour – Wikipedia.
