Pierre Louis Dulong
Who was Pierre Louis Dulong?
French scientist (1785-1838)
Biographical data adapted from Wikipedia’s article on Pierre Louis Dulong (CC BY-SA 4.0).
Biography
Pierre Louis Dulong was born on February 12, 1785, in Rouen, France, and became a key scientific figure of the early 1800s. He studied at the École polytechnique and the Paris Medical Faculty, where he received a strong mathematical foundation alongside practical experimental skills. He eventually left medicine to focus on research in chemistry and physics. During a time of vigorous scientific activity in France, he was involved with major scientific institutions in Paris, including the École polytechnique, where he later worked as a professor and administrator.
Dulong's early chemical research put him in risky situations. While studying nitrogen trichloride, an unstable compound, he experienced severe injuries from repeated explosions, losing a finger and the use of one eye. Despite these challenges, he persisted in his research with determination. His efforts caught the eye of leading figures in French science, like Claude Louis Berthollet, who supported and mentored him, helping Dulong secure his place in the Parisian scientific community.
Dulong's most famous collaboration was with Alexis Thérèse Petit, a talented physicist at the École polytechnique. In 1819, they published their findings, which led to the Dulong–Petit law. This law noted that the specific heat capacity of a solid element, when multiplied by its atomic weight, gives a roughly constant value. This finding provided early support for atomic theory and was a useful way to estimate atomic weights, making it a valuable tool in 19th-century chemistry. After Petit died in 1820, Dulong continued their work alone.
In addition to their law, Dulong conducted extensive studies on steam's elasticity and pressure, which were important for the growing use of steam engines in industry. His accurate measurements of the specific heats of gases and his studies on the refractive indices and expansion of gases were seen as foundational contributions. He also worked on heat conduction and worked with Dominique François Jean Arago on measuring refraction in gases. In 1826, he was elected a Foreign Member of the Royal Society in London, a sign of his high regard among European scientists. His name is among the 72 scientists and engineers on the Eiffel Tower.
Dulong was director of studies at the École polytechnique from 1830 until his death, significantly shaping the education of French scientists and engineers. His health worsened in his later years, and he died in Paris on July 19, 1838. Although he published fewer works than some of his peers, the accuracy and originality of his experimental work earned him a respected place in the history of physical science.
Before Fame
Pierre Louis Dulong was born in France just before the revolution. Orphaned young, he was raised by an aunt and was smart enough to get into the prestigious École polytechnique in Paris, founded in 1794 to train engineers and scientists for the French state. He then studied medicine at the Paris Medical Faculty but found being a doctor wasn't for him, so he shifted his focus to experimental science.
In his early research years, Dulong struggled financially. He worked in relative poverty until chemists like Berthollet noticed him. Their support helped him join the Société d'Arcueil, an informal group of leading French researchers. This connection was crucial, providing him with lab resources and collaboration opportunities that he couldn't afford on his own, and it enabled him to do the sustained experimental work that eventually earned him recognition.
Key Achievements
- Co-discovery of the Dulong–Petit law relating atomic weight to specific heat capacity, published with Alexis Thérèse Petit in 1819
- Pioneering experimental studies on the elasticity and pressure of steam at high temperatures, relevant to industrial steam engine safety
- Extensive measurements of the specific heats, refractive indices, and expansion coefficients of gases
- Election as a Foreign Member of the Royal Society in 1826, recognizing his contributions to European physical science
- Long tenure as director of studies at the École polytechnique, significantly influencing French scientific and engineering education
Did You Know?
- 01.Dulong lost a finger and the sight of one eye in separate laboratory explosions caused by nitrogen trichloride, a compound he was among the first to study systematically.
- 02.The Dulong–Petit law of 1819 was used to correct mistaken atomic weight assignments for several elements, including for chromium and tellurium, by providing an independent check on values calculated by other means.
- 03.Dulong served as director of studies at the École polytechnique for the last eight years of his life, shaping the education of the engineers and scientists who would lead French industrial and scientific development through the mid-nineteenth century.
- 04.His name appears among 72 scientists, engineers, and mathematicians permanently inscribed on the exterior of the Eiffel Tower, a distinction decided by Gustave Eiffel to honor contributors to French science and industry.
- 05.Despite the importance of his steam elasticity research to industrial applications, Dulong conducted the work in a purely academic context, and it was later used as a reference by engineers designing safer boilers during the steam power expansion of the 1820s and 1830s.
Family & Personal Life
Awards & Honors
| Award | Year | Details |
|---|---|---|
| Foreign Member of the Royal Society | 1826 | — |
| 72 names on the Eiffel Tower | — | — |