François Stanislas Cloez (1817 – 1883)

François Stanislas Cloez (1817 – 1883)

Author: Vera Koester ORCID iD

François Stanislas Cloez was born on June 24, 1817, in Ors, France, into a family of farmers. He began an apprenticeship as a pharmacist in Valenciennes and Tournay, both France, and then went to Paris.
In 1841, he won an internship in the Parisian Hospitals. At the same time, he studied at the École Supérieure de Pharmacie. In 1846, he entered the Museum d’Histoire Naturelle, Paris, as a Preparateur working with Michel Eugène Chevreul. In 1851, he was appointed Réparateur at the École Polytechnique in the southern suburbs of Paris, in 1867, Professor of Physics at the École des Beaux-Arts, Paris, succeeding Louis Pasteur, and in 1872, Examinateur de Sortie (final examiner) at the École Polytechnique, succeeding Victor Regnault. Simultaneously, he studied medicine at the Faculté de Médecine in Paris.

In 1866, Cloez was awarded the degree of Pharmacien de Première by the École Supérieure de Pharmacie after successfully defending a dissertation on the oxidation of vegetable fats. In the same year, he received his doctorate Docteur ès Sciences from the Faculté des Sciences of the University of Paris, after defending a dissertation on cyanic esters. In his medical studies, he passed all examinations but never finished his dissertation [1].

In 1866, Cloez was appointed Chevalier of the Legion of Honor. He was a founding member of the Société Chimique de France (French Chemical Society), its treasurer, and in 1868, its President. In 1879, he was elected a leading member of the Conseil d’Hygiène de la Seine (government agency created in the 19th century for public health purposes), and in 1882, he became its President.

François Stanislas Cloez wrote about 100 papers and books in the fields of plant chemistry and physiology, analytical and organic chemistry, nitrification, animal poisons, metallurgy, etc. He died in Paris on October 12, 1883.


Essential Oils [2,3]

In the 1870s, François Stanislas Cloez began identifying the constituents of individual essential oils and dividing them into groups according to their suitability for medical, industrial, and perfumery purposes. Cloez was the first chemist to report on the properties of the leaves and chemicals from eucalyptus. He identified the main component of eucalyptus oil, which he called “eucalyptol” (cineol). In honor of his work, Eucalyptus cloeziana, commonly known as Gympie messmate or dead finish, was named after him.

François Cloez also studied the vegetation of plants living underwater [4], the composition of pollen [5], the volatile oil in nutmeg, the seeds of the tung-oil tree of China and their substances, new acids containing arsenic, sulfur, and oxygen [6], and much more.


Cyanamides [7]

In 1851, Cloez and the Italian chemist Stanislao Cannizzaro jointly produced cyanamide (CN2H2). They found that bubbling dry gaseous cyanogen chloride through an ethereal solution of ammonia resulted in a mixture of ammonium chloride and an amide, which they named cyanamide.

At that time, different values of the atomic mass of carbon and nitrogen were used, so they described the formula of cyanamide as C2H2N2 instead of CN2H2.


Orgueil Meteorite [8,9]

In 1864, a meteor, split into many pieces, fell in the vicinity of the village of Orgueil in southwest France. Cloez was among the first scientists to analyze a piece of the Orgueil meteorite, a carbonaceous chondrite. The presence of organic matter in the Orgueil meteorite gave rise to a scientific discussion about the possibility that it could have a biological origin. Cloez wrote that the meteor contains carbon, hydrogen, and oxygen, and the composition is very similar to the peat from the Somme valley in France, or the brown coal from Ringkohl near Kassel in Germany. “The composition of this carbonaceous matter seems to indicate the existence of organized organic beings in celestial bodies.”

A fragment of the meteor was kept sealed in a glass vessel and was re-examined in 1965. Seed capsules and pollen grains camouflaged with carbon dust was found embedded in the meteor. The outer “melting layer” of the meteor turned out to be an adhesive. Orgueil is extremely soft and clayey when it comes into contact with water. It is believed that someone has wetted the rock and introduced the plant fragments into the interior of the rock. Although the culprit is unknown, it is assumed that the hoax was aimed at influencing the 19th-century debate on the spontaneous generation of life. There is no evidence that Cloez was involved in this swindle.



[1] Jaime Wisniak, Revista CENIC Ciencias Biológicas 2017, 48(2), 57–68.

[2] F. S. Cloez, Compt. Rend. 1870, 70, 687.

[3] E. Jahns, Ueber Eucalyptol, Berichte der deutschen chemischen Gesellschaft 1884.

[4] S. Cloëz, Gratiolet, Untersuchungen über die Vegetation unter dem Wasser lebender Pflanzen, Journal für Praktische Chemie 1851.

[5] Fremy, Cloëz, Ueber die Zusammensetzung des Pollen, Journal für Praktische Chemie 1854.

[6] Neue Arsen, Schwefel und Sauerstoff enthaltende Säure, Justus Liebigs Annalen der Chemie 1845.

[7] F. S. Cloez, S. Cannizzaro, Recherches sur les Amides Cyaniques, Compt. Rendus. 1851, 32, 62-64.

[8] Edward Anders, Eugene R. DuFresne, Ryoichi Hayatsu, Albert Cavaille, Ann DuFresne, Frank W. Fitch, Contaminated Meteorite, Science 1964, 146(3648), 1157–1161.

[9] Matthieu Gounelle, Michael E. Zolensky, The Orgueil meteorite: 150 years of history, Meteoritics & Planetary Science 2014, 49(10), 1769–1794.


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