Dulong entered Polytechnique at sixteen and first practised medicine before giving himself entirely to the physical sciences. In 1819, with Alexis Thérèse Petit, he stated a law on the heat of simple bodies: it still bears both their names, and the textbooks still teach it. Perpetual Secretary of the Academy of Sciences, he died at fifty-three.
The story
Pierre Louis Dulong entered the École polytechnique at sixteen, in the intake of 1801. Born at Rouen on 14 February 1785, a pupil of Berthollet and Thénard, he practised medicine first before giving himself entirely to chemistry and physics.
In 1819, with Alexis Thérèse Petit, he established the law on the heat capacities of simple bodies that still carries both their names — like the law of Biot and Savart, it outlived its authors in the textbooks. He became perpetual secretary of the Academy of Sciences, the highest office in the institution.
He died in 1838, at fifty-three. His epitaph names the donors before the dead man: “Érigé par ses élèves et ses nombreux amis à la mémoire de Pierre Louis DULONG, secrétaire perpétuel de l'Académie des Sciences.” The formula returns on several graves at Père-Lachaise and always says the same thing: the dead man had left nothing with which to pay for his monument. One title is kept, the highest; the law is not there.
The grave
A monument whose inscription names the donors before the dead man: “Érigé par ses élèves et ses nombreux amis à la mémoire de Pierre Louis DULONG, secrétaire perpétuel de l'Académie des Sciences.” — erected by his pupils and his many friends to the memory of Pierre Louis Dulong, Perpetual Secretary of the Academy of Sciences. The formula recurs on several tombs at Père-Lachaise — Lefébure-Wély, Cartellier, Danbé — and always says the same thing. A single title is retained, the highest; nothing of the Dulong–Petit law, which is nonetheless what survived him.
On site, do not miss
The epitaph names the donors before the dead man: “Érigé par ses élèves et ses nombreux amis à la mémoire de Pierre Louis DULONG, secrétaire perpétuel de l'Académie des Sciences.” — erected by his pupils and his many friends to the memory of Pierre Louis Dulong, Perpetual Secretary of the Academy of Sciences.
Visitors' questions
Where is Pierre Louis Dulong's grave?
In Division 8, avenue Casimir-Perier, fourth row. His epitaph says who paid for the monument: “Érigé par ses élèves et ses nombreux amis à la mémoire de Pierre Louis DULONG”, raised by his pupils and his many friends. He died in 1838, at fifty-three.
Xavier BichatWhat is the Dulong-Petit law?
The law established in 1819 with Alexis Thérèse Petit on the heat capacities of the simple substances: it is still taught under both their names, like Biot and Savart's.
Louis Joseph Gay-LussacWas he a doctor?
To begin with, yes: he practised medicine before turning to chemistry and physics. He had entered Polytechnique at sixteen and had Berthollet and Thénard for masters. He later became Perpetual Secretary of the Academy of Sciences.
François MagendieWho paid for his monument?
“His pupils and his many friends”, says the inscription. The formula comes back on several graves in the cemetery — Lefébure-Wély's, Cartellier's — and always says the same thing: the dead man was not rich.
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