Exploring the Limits — Pierre-Louis Dulong
Pierre-Louis Dulong was a member of the first generation of modern scientists. Dulong was not a charismatic personality, unlike his flamboyant contemporary and some-time collaborator Francois Arago, and Dulong never attained a high-ranking position. Instead, Dulong spent his life quietly teaching and working in the laboratory, where he felt most at home, but he did not shy from the challenge of exploring the hazardous outer limits of chemistry and physics.
Dulong had an aptitude for designing and carrying out experiments, and he used this talent to answer questions posed by new theories that were emerging in areas of chemistry and physics. For this reason, he found work in the laboratories of leading scientists during the post-Revolutionary period, the early 1800s.
Dulong was among a select few invited to join the Society of Arcueil, a private research laboratory set up by Claude Louis Berthollet and Pierre Simon Laplace in a small town outside of Paris. There, Dulong joined other scientists who became leaders in the fields of chemistry and physics during the first half of the 19th century. The work of the Society of Arcueil contributed to our present understanding of molecules and atoms, electricity and magnetism, heat, and light.
Dulong is remembered for his research into the chemical composition of water, the physical properties of water vapor and steam at high temperature, and his work to precisely measure temperature and the specific heats of various substances. This work, which Dulong carried out with Alexis Thérèse Petit, resulted in the discovery of the Dulong-Petit law. But, Dulong was famous among the chemists of his day for being the first person to synthesize nitrogen trichloride, a notoriously unstable and highly explosive substance.
At the beginning of the 19th century, much research in chemistry was devoted to isolating distinct compounds and discerning their molecular composition. As this work progressed, people remarked on the fact that no one had yet found a substance composed of nitrogen combined with chloride. Was there some as yet unknown law of chemistry that prohibited this combination?
Dulong took up the challenge of finding out. He succeeded in producing an oily, yellow substance — nitrogen trichloride — by reacting chlorine gas with ammonium chloride in solution while carefully maintaining a low temperature for the reaction. However, this success came at the cost of three fingers and an eye, when the long-sought substance violently exploded in Dulong’s face.
On learning of Dulong’s success, English scientists Sir Humphrey David and Michael Faraday set out to replicate this achievement, which they did almost exactly. Sir David caught a shard of glass in his eye, and Faraday injured his hand when the product of their experiments blew up on them as well.
Pierre-Louis Dulong is one of the 72 scientists and engineers named on the Eiffel Tower.
