Revista CENIC. Ciencias Químicas ISSN: 1015-8553 [email protected] Centro Nacional de Investigaciones Científicas Cuba

Wisniak, Jaime Jean Darcet Revista CENIC. Ciencias Químicas, vol. 35, núm. 2, mayo-agosto, 2004, pp. 105-110 Centro Nacional de Investigaciones Científicas La Habana, Cuba

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RESEÑA BIOGRAFICA

Jean Darcet

Jaime Wisniak

Department of Chemical Engineering, Ben-Gurion University of the Negev, Beer-Sheva, Israel 84105. [email protected]

Recibido: 13 de noviembre de 2003. Aceptado: 30 de diciembre de 2003.

Palabras clave: minerales, altas temperaturas, porcelana dura, cerámica, aleación Darcet Key words: minerals, high temperatures, true porcelain, ceramic, Darcet’s alloy.

RESUMEN. Jean Darcet (1724-1801) es otro de los científicos Franceses famo- Medicine in Bordeaux, against the sos que dedicó su vida a la educación, la ciencia y al desarrollo de la industria wishes of his father who wanted him nacional en el período crítico de la Revolución. Su muy conocida memoria so- to study law and make a career in the bre el comportamiento de los minerales a altas temperaturas condujo a una judiciary system. As a result, his fa- mejor clasificación de estos y a descubrir el método de fabricar porcelana dura, ther disinherited him, with the ac- un evento que hizo a Francia independiente de fuentes externas y transformó a quiescence of his stepmother Sévres en un industria de cerámica mundialmente famosa. Darcet descubrió la Jeanne d’Arbins who seemed keen aleación que lleva su nombre, un material que encontró muchos usos industria- in seeing the fortune go to her chil- les, aun en nuestro tiempo. dren. In order to survive in Bor- deaux Jean started giving lessons of ABSTRACT. Jean Darcet (1724-1801) is another of the famous French scientists Latin and Greek to the children of that devoted his life to teaching, to science, and to the development of the na- tional industry at the critical time of the Revolution. His well-known memoir the middle-class. Eventually, one of on the behavior of minerals under high heat led to a better classification of his young friends, Augustin Roux them and to his discovery of the method for making true porcelain from native (1726-1776), a physician (who would raw materials, a finding that made France independent of external sources and afterwards become professor of transformed Sévres into a world-famous ceramic industry. He discovered the chemistry at Faculty of Medicine) in- alloy that carries his name, a material that found many industrial uses, even in troduced him to Charles de Secondat our time. Montesquieu (1689-1755), who took him to Paris in 1742, when he was just 18 years old, to tutor one of sons, Jean-Baptiste Secondat (1797-1871). LIFE AND CAREER1-4 While working in this position he Jean Darcet (Fig. 1) was born on helped Montesquieu gather the ma- September 7, 1724, at Audignon, terial for his masterpiece L’Esprit des near Doazit, St. Sever, Landes, Lois (1748). France, the son of Marguerite In 1762 Darcet was awarded his d’Audignon and François Darcet. His medical degree and although on No- father was a well-known judge in vember 18, 1762 he was appointed Doazit who later became lieutenant docteur-régent (Note 1) at the Fac- general at the Gascogne bailiwick. ulty of Medicine he never practiced His mother passed away in 1728 and medicine. His strong interest in sci- afterwards his father married ence led him to attend the courses Jeanne d’Arbins. At the age of 12 in chemistry given at the Jardin du Jean entered the religious school of Roi by Guillaume François Rouelle d’Aire and in 1740, after finishing his (1703-1770), the most famous phar- Fig.1. Jean Darcet (1724-1801). 5 studies and having shown a strong (By permission of Edgar Fahs Smith Col- macist of his time. Rouelle influ- interest for sciences, he decided to lection, University of Pennsylvania Li- enced him in such a manner that not study medicine at the Faculty of brary). only they started working together

1. In order to be admitted to the Faculty of Medicine it was necessary first to obtain the Maîtrise ès-Arts (Master of Arts) of the Université de Paris, then at the Faculty, to obtain successively the degrees of Bachelier (bachelor), Licencié, Docteur, and finally Docteur Régent that gave the right to teach at the Faculty. To become a Bachelier it was necessary to pass a qualifying exam; followed by two years of study and the approval of four theses to obtain the degree of Licencié. Approval of the four theses led to the award of the degree of Docteur. The total fees for obtaining all these degrees were about 6 000 livres. 105 Revista CENIC Ciencias Químicas, Vol. 35, No. 2, 2004.

but also he spent the rest of his life daughter Françoise Amélie. The structure of the one given by Rouelle, studying chemistry. A major factor bride was then 18 years and died in in which the knowledge of chemis- to his appointment to the Collège de 1791 at the age of 38. They had four try was explained along the lines of France in 1774 was the fact that children, two boys (one of them died the mineral, animal, and vegetable among all the physicians being con- in infancy) and two girls. When Ma- kingdoms. His auditorium was al- sidered, he was the only who had dame Rouelle also died, her aunt, a ways full. In 1784 he took on an as- made chemistry his sole occupa- young sister of Madame Rouelle sistant, Jérôme Dizet (1764-1852), a tion.6 kept house for him and the three nineteen-year-old pharmacist ap- Darcet, little by little, specialized children.6 prentice from his native region in in the theoretical study of chemis- On December 1774 Darcet was Les Landes. Dizé prepared the dem- try, looking for the application of appointed to the first chair of experi- onstrations and experiments and theory to practice. His opportunity mental chemistry at the Collège de performed the same service for the came with the count Louis de France. His inaugural speech was course in experimental physics, Lauraguais (1733-1824), a nobleman symbolized by some drastic changes which Louis Lefêbre de Gineau interested in chemistry and indus- in the traditions of the Collège not (1751-1829) had begun teaching in trial entrepreneur. At that time all only because he was allowed to give 1786. Dizé was an extremely meticu- objects made of quality porcelain it in French instead of Latin but also lous worker that relieved Darcet of were imported from China and Ja- without wearing the traditional robe. most of the experimental duties re- pan; all French efforts to manufac- The authorization for lecturing in lated to the course. Darcet taught for ture true porcelain (porcelaine dure) French was more one of public rela- 27 year at the Collège de France; he with local materials had failed com- tions than factual, it was said that became known as a remarkable pletely. After the death of the duc Latin did not have enough techni- teacher, by the content of the courses d’Orleans, Montamy, his maître cal terms to express appropriately he taught, the clarity of exposition, d’hôtel, approached Lauraguais with Darcet’s scientific terms. In fact, and the logic of his reasoning. the claim that his laboratory had Darcet’s concepts were not that dif- Recognition by the Académie de found a method for making true por- ferent from previous scientific lec- Sciences came late to Darcet. On celain from raw materials found in tures given at the Collége; in addi- April 4, 1784, at the age of fifty-nine, France. Lauraguais became ex- tion, he was very well versed in Latin he was appointed associé chimiste tremely interested in this possibil- and Greek, as seen by his early oc- supernuméraire to the Académie de ity; he purchased the remaining cupation as a tutor in both lan- Sciences in replacement of Pierre- material from Montamy together guages. Joseph Macquer (1718-1784), and re- with several finished pieces and se- The creation of the chair of ex- mained a member until its suppres- cured the help of Leguay, the arti- perimental chemistry at the Collége sion in 1784. The supernumeraries san responsible. He then approach- was accompanied by promises from were scientists of prestige, nomi- ed Rouelle to assist him engage a the ministers Anne Robert Jacques nated by the King without previous chemist to help in this project. Turgot (1727-1781) and Chrétien presentation to the Académie and Rouelle recommended Darcet. Guillaume de Malesherbes (1721- destined to become titulaires (Note Darcet, together with his patron, 1794) to provide the space and equip- 2). In 1785 the government created Roux, and Leguay, studied more ment for a research laboratory. This the Institute de France and Darcet than 200 earths, minerals, and me- turned out not to be the case, space was among the first members of the tallic oxides, until eventually he dis- for a laboratory was provided but not institution. covered the procedure for manufac- funds for the equipment and ancil- After the occupation of Hanover turing true porcelain. The kaolin of laries. Darcet had to supply his own during the Seven Year war (1756- St.-Yrieix was discovered in 1768 and equipment, reagents, and fuel, 1763), Darcet had the opportunity of Limoges surged ahead in 1772. At which he paid from his salary (at that studying the local copper and iron about the same time Darcet, who was time 1 200 francs) and his own pri- mines, as well as the local metallur- already a consultant with authority vate resources. He did not have gical industry. Darcet first major in the chemical aspects and traveled much difficulty in doing so because work was a long series of experi- to Sèvres several times a week, his wife brought him a substantial ments on the action of strong heat signed together with Macquer and dowry, together with Rouelle’s stock on minerals. The most significant Hilaire-Marin M. Rouelle (1718- and apparatus. He was a hard work- memories he published on the sub- 1779), the brother of Guillaume, a ing chemist, and it was a matter of ject were two Mémoires Sur l’Action certificate reporting that various pride to be teaching his science on de Feu Dans un Grand Nombre de pieces of pottery submitted for a the most advanced level at the Terres, published in 1766 and 1771.7,8 privilege by a certain Brolliet were Collège. In 1778 he assured the min- His results, read to the Academy in just a low-grade faïence.6 istry that his demonstrations and ex- 1766 and 1768, represented an exten- A year after Rouelle’s death his periments were as full as if he had sion and improvement of the work widow carried out the wishes of her been giving private lectures for sub- of Johann Heinrich Pott (1692-1777), husband and as a testimony of their scribers.6 who In 1746 had found that clay confidence in him in 1771 she of- Darcet’s chemistry course at the earths and stones, although not fus- fered to Darcet, then 41, to marry her Collège followed more or less the ing when heated alone, did so when

2. In 1785 the Académie was reorganized, the adjoint category was eliminated, and eight classes were created: geometry, astronomy, general physics, anatomy, chemistry and metallurgy, botany and agriculture, natural history, and mineralogy. Each class had six members, and three pensionnaires; in addition, twelve free associates and eight foreign associates. The surméraires were eliminated and the adjoint geographer became the associate geographer. 106 Revista CENIC Ciencias Químicas, Vol. 35, No. 2, 2004. heated under the proper proportions His wide experience in indus- Anton Mesmer (1734-1815) and his with calcareous earths and stones.9 trial activities led to his being picked magnetic fluid (the cures achieved Darcet’s findings helped to clarify by the government to participate in were explained by reasons different the ideas about the classification of the direction of several manufactur- from animal magnetism). During minerals and eventually they also ing activities of the state. For ex- the last few years of his life Darcet led to the improved production of ample, Darcet occupied several im- did little original work, but he served true or hard porcelain in France. portant positions at the Manufacture on a number of government com- These memoirs were followed by re- Royale de Sèvres. First he became missions and contributed several ports on the action of heat on the inspector of colors, then one of the reports for the Academy. diamond and other precious stones8, representatives (commissaire) of the The many intrigues going on at in which he demonstrated the com- Académie in the directing body, re- that time in France led the Conven- plete destructibility of the diamond placing Étienne Mignot de Montigny tion to charge Darcet with the ma- when it was heated in air and distin- (1714-1782) who had recently died; cabre accusation of manufacturing guished it from other precious and in 1784 he became Directeur of cups of gelatine using the bones of stones, such as rubies and emeralds the factory, replacing Macquer. Ac- Jean-Baptiste Molière (1622-1673), (see below). He occupied himself cording to Gillespie6 there is no evi- Blaise Pascal (1623-1662), Hélöise with metallurgy and coins; discov- dence on the reasons why the (1101-1164) and Abélard (1079-1142), ered the fusible alloy (alliage fusible, compte Charles Claude d’Angiviller etc. Another rumour said that he had a mixture of tin and bismuth, (1730-1809) selected Darcet instead used the bones for preparing the cal- Darcet’s alloy) (see below), melting of Fourcroy to succeed Macquer. cium phosphate required for manu- at the temperature of boiling water During his tenure at Sèvres Darcet facturing a porcelain cup at Sèvres, and in 1775 found a use for it in the perfected the different manufactur- on which he and friends had drank production of stereotype plates; by ing procedures and demonstrated patriotically to the Republic. He was 1860 Darcet’s alloy was also em- the identity between the scarlet dye again condemned to the guillotine ployed in the valves of steam en- obtained from the wild cochineal of but managed to escape the night gines. Santo Domingo with the one ob- before he was to be decapitated. In 1783 he read a memoir on the tained from the Mexican variety. Af- Darcet died on February 12, 1801, action of heat on calcareous earth ter the death of Mathieu (1714-1791), at the age of seventy-five, during vio- (calcium carbonate) where he proved general inspector of coin assay, lent intestinal spasms, probably that the ability of this material to Darcet was promoted from adjoint to caused by a gout metastasis. Georges scavenge other earths and minerals Director of the Mint. Cuvier (1769-1832) pronounced the during the fusion of glass was due His many academic and indus- Éloge Funèbre.1 to its alkaline nature.10 trial activities made Darcet very Darcet’s work on the geology of rich; he devoted part of his patri- HONORS AND POSITIONS the Pyrenees and his researches on mony to different philanthropic ac- Darcet received many honors for the action of strong heat on calcare- tivities, particularly for hospitals. his contributions to science, indus- ous earth indicate that his interest In 1789, at a time when only the try, and the Nation. He was a mem- in mineral and their analysis domi- esteem determined the right to vote, ber of the Lycée des Arts and one of nated his work throughout his ca- he was selected as Elector for the city its founders, Professor of chemistry reer. Nevertheless, he did work and of Paris. After Maximilien Robespierre at the Collège de France, member of contributed in several other fields, (1758-1794) took the government, he the Académie des Sciences, honor- as illustrated by the application of wanted Darcet be put in the list of ary member of the Collège de nascent electricity to the cure of ner- suspects because of his close rela- Pharmacie, member of the senate; vous ailments11, the possibility of tion with the Duke of Orleans (the member of the Sociéte Royale preparing gelatine from the nutri- Duke was tried and beheaded on d’Agriculture, Inspector General of tive matter in bones, trnaslating into November 6, 1793), who had fi- Assays of Coins, and Inspector of the French of the work on viper venom nanced part of his researches. Darcet Manufactures Nationales de Sèvres by Felix Fontana (1730-1805), as well was put in the list of those to be guil- et des Gobelins. as annotating Joseph-Louis Lagrange’s lotined, but was saved by the inter- (1736-1813) translation of Seneca’s vention of Antoine-François Fourcroy Scientific contribution Questions Naturelles. Darcet was (1750-1809) who explained to Robes- Some of the most important con- also called by the Duc d’Orleans as a pierre the true nature of his relation tributions of Darcet will now be de- referee of Nicolas Le Blanc’s (1742- to the Duke, indicating not only that scribed with more detail.

1806) proposal for converting com- it antedated the Revolution, but also 7,8,13 mon salt into soda, or mineral alkali. the importance of Darcet’s scientific 1. Hard porcelain Darcet was extremely busy at that discoveries to France and science. Darcet and his patron, the count time and turned the matter over to Darcet, after this incident, hid for of Lauranguais, studied more than Dizé. When Dize’s first attempts to some time with his family at Prouilh. two hundred soils, minerals, and reproduce Le Blanc’s results failed, At the end of 1800, the Constitu- metal oxides and eventually were the latter requested that the initial tion of the year VIII, through its four able to determine the constituents report be delayed and that Dizé con- assemblies, created the Senate, to and proportions of the materials tinue working with him in order to which Bonaparte incorporated all needed for the manufacture of true find and overcome the source of the the illustrious of France. Darcet was porcelain (porcelaine dure). Under difficulty. Dizé agreed, with the con- one of the first Senators and put his the direction of Darcet the manufac- currence of Darcet, and thus did the intelligence and talent to the service ture of porcelain at Sèvres achieved development of the Leblanc process of the country. He was part of the numerous improvements. The begin in the laboratory of the Collège Committee that examined and con- changes he made in the composition de France.12 demned Louis XVI, as well as Franz of the paste allowed the manufacture 107 Revista CENIC Ciencias Químicas, Vol. 35, No. 2, 2004.

and burning of large vases made of degradation of the Pyrenean, and ous Bodies to turn them into Fire and one piece, which could not be the agents of the phenomenon were Flame ” Hence, according to Newton, burned before but only divided into first water, then avalanches, the diamond was highly combustible. five or six related pieces. The deli- melting of snow, and infiltrations. Of Between 1694 and 1695 Jean- cate coating of porcelain was changed course there were usual possibilities Gaston de Médicis, Grand Duc of and made more beautiful; he con- such as earthquakes, alternation of Tuscany (Cosmo III), had seen in ceived a fumigation process that was dry and wet years, gel, and vegeta- Florence diamonds destroyed by a afterwards applied in the muffles of tion. Darcet then posed a series of burning mirror during an investiga- the painting ovens in order to give questions: The summits, where the tion he had commissioned from the colors on porcelain an iridescent rocks are nude, where they covered Giuseppe Averani (1662-1738) and appearance, as well as having more with slime before erosion took place? Giovanni Targioni (1712-1783) to variegated shades; he also developed Was the Aquitain basin a sea some- pursue further Boyle’s experiments. some important improvements on time, as indicated by the presence of Similarly, François Etienne de the porcelain ovens themselves. He sedimentary layers? Had the Pyrenean Lorraine (who afterwards became participated in the detection and in ancient times be a uniform bank, Grand Duc of Tuscany and then the exploitation of the St. Yrieix kaolin which afterwards slit all around? emperor François I) had spent a for- deposits in 1768 and thus the manu- Finally, the fact that this mountain tune commissioning different ex- facturing enterprise at Limoges chain did not have a volcano, like the aminations trying to burn diamonds came up in 1772. Andes Mountains, seemed to indi- and rubies.16 Up to Darcet’s time it Darcet’s results at Sèvres were cate a very old existence. was believed that the actual result so significant that it was said that Darcet and his friend, Gaspar was just a simple evaporation, with- “les Saxons avoient bien le secret de Monge (1746-1818), a professor of out the intervention of air. Many sci- leur belle porcelaine, mais qu’ils ne physics at Mézierfes, used their va- entists found these results difficult connoissoient pas l’art de faire la cations to make barometric and tem- to believe until Darcet published the porcelaine” (the Saxons have the se- perature measurements in the results of his work on the action of cret of their beautiful porcelain, but Pyrenean. Darcet raised afterwards strong heat on materials.7,8 Darcet do not know the art of making por- the question that if it was certain showed that diamond was combus- celain).1 that the air became rarified with tible when heated in the presence of height, or was the reason simply the air in a simple muffle and at a tem- 2. Geology of the Pyrenees changes in air density caused by the perature inferior that needed to melt Darcet was very fond of hiking in oscillations of the barometer? Since gold; diamonds did not withstood the Pyrenees alone and with his col- Darcet felt that at the top of the long heating in a furnace, even when leagues, and inspecting the different mountain he could breath easily, he surrounded by a thick porcelain geological features. Interestingly could not square this fact with the paste. Darcet memoir convinced enough, the result of his observa- claim that at higher heights air be- most chemists that diamonds could tions was the subject of his inaugu- came rarified. He believed that those be destroyed by heat, but many jew- ral address when appointed to the who had reached higher heights had ellers and diamond merchants were chair of experimental chemistry at became dizzy and bleedy simply be- unable to accept these results, for, the Collège de France (Discours en cause they had become very tired. from very early times, they have Forme de Dissertation sur l’Ètat Darcet thought air was a fluid like been accustomed to remove or di- Actuel des Montagnes des Pyrénées water, having essentially a constant minish flaws from diamonds by ex- et les Causes de leur Dégradation).14 density. posing them to a strong heat for In the opening statements he re- some time. As told by Macquer16 Le 3. The burning of diamond contro- ferred in general to the modifica- 15,16 Blanc, a well-known Parisian jewel- tions caused by erosion to the sur- versy ler, offered to provide a diamond, to face of the globe, and then its appli- It was generally believed that prepare it in its usual manner, and cation to the Pyrenean chain, par- diamond was indestructible under to submit it to Darcet and Rouelle’s ticularly the valleys on the French the action of high heat, Robert Boyle tests. They surrounded the stone side. He described in general terms (1627-1691) was the first to study with a paste of chalk and charcoal the great catastrophes and destruc- with some precision the action of fire and placed it in a crucible sur- tions that had afflicted the Pyrenees on diamond and Isaac Newton (1642- rounded by sand (this was the pro- in the past and examined in detail 1727) had predicted that diamond cedure used by diamond jewellers to their present state and composition. could be burned and had thus clas- treat the stone). After three hours In his opinion these valleys had been sified it in the class of combustible heating the diamond was found to created by water, as could be seen substances. In his book Opticks17 have vanished completely. This fact from the lateral layers that built its Newton, after presenting a table of suggested (again) that its destruc- slopes. He described the geology of the values of the ratio between the tion was due to the volatilization the Barèges valley with its rising refractive power and the density for rather than to combustion or burn- soil, the original rock born at its twenty-two substances (diamond ing or decrepitating into fragments summit, and the possibility that the had the largest value, 14,556) wrote: too small to be observed.18 Iray Peak at Saint-Jean-Pied-de-Port “all Bodies seem to have their refrac- In July 1771, Godefroide Ville- was made of eroded stones by the tive Power proportional to their taneuse and Macquer heated a dia- simple action of rock disintegration Densities it seems rational to at- mond (to a temperature not higher by the climate. In the same terms he tribute the refractive Power of all than to turn copper red) in a crucible described the geological features of bodies chiefly, if not wholly, to the in Macquer’s furnace, in the pres- the summit of Pic du Midi. The roll- Sulphureous Part with which they ence of Darcet, Rouelle, and others. ing rocks located all over the abound. And as Light congregated by After 20 min heating the crucible Aquitain basin originated from the a Burning glass acts upon Sulfure- was opened and the observers no- 108 Revista CENIC Ciencias Químicas, Vol. 35, No. 2, 2004. ticed that the diamond appeared to mond was subjected to the heat from ratus for preparing the lye and for be enveloped in a small pale phos- the Academy’s large burning-glass,22 soap boiling operation; the charac- phorescent flame. They repeated the it decrepitated and split into tiny teristics of the resulting soaps, and procedure for another half hour with fragments, but this did not happen the instruments used for measuring the same stone and on opening the if the heat was applied gradually, the strength of the lye. They also furnace found that the diamond had when the diamond slowly disap- made a comparison of the soaps ob- been completely destroyed.16 An ac- peared without giving off any smell tained from different oils and clas- count to the experiments was read or visible fumes. sified the oils in the following order to the Academy the following day. Sometime later Louis-Bernard of decreasing fitness for soap: (1) ol- Further experiments were made Guyton de Morveau (1737-1816) ac- ive and sweet almond oils; (2) tallow, later by Rouelle and Darcet.19 complished the combustion of dia- lard, rancid butter, and horse oil, (3) Stanislas Marie Maillard, despite mond in the presence of oxygen and rapeseed oil, (4) beechnut and the failure of Le Blanc’s experiment, suggested that it was made of pure popyseed oils, (5) walnut and linseed offered three diamonds for experi- carbon. Additional experiences with oils, (6) hempseed oil, and (7) fish oils. ment, which he surrounded very strong heat led Darcet to prove that Darcet, Lelièvre, and Pelletier carefully with charcoal and sand, rubies, sapphire, emerald, topaz, al- also studied the methods for mak- and this time, after two hours of though having similar properties to ing hard soaps from potash soaps by heating, the diamond was found to diamond had a completely different the addition of salt solution to the be unchanged This result was quite nature.23 soft soap and boiling the mixture for unexpected by Macquer, who con- several hours. They also considered cluded from it, and from the flame 4. Soap manufacture the methods for making fraudulent that he had seen before on the sur- Darcet tried to obtain soda from soaps, particularly by the addition of face of a red-hot diamond, that dia- marine salt, and manufactured soap water, salt, alum, starch, chalk, and monds were combustible and, like from all types of oils and fats. By the lard. According to them, the only other bodies, required air for their end of the eighteenth century, the way of identifying the adulterants combustion. Subsequently Maillard only comprehensive account of soap was by analysis. allowed Macquer to repeat the ex- making then extant was the almost The final part of the report was periment in the furnace of the fac- 100 page long “Rapport sur la Fabri- a set of instructions for those who tory at Sèvres, with a diamond he cation des Savons” published in wanted to make soap by themselves. had packed as before, to prevent con- 1797 by Jean Darcet (1725-1801), 25,26 tact with air. Again, the stone was Claude-Hugo Lelièvre (1752-1835), 5. Alloys unharmed by the fire.16 and Bertrand Pelletier (1761-1797).24 During his work on fusible alloys Antoine-Laurent Lavoisier (1743- The Committee of Public Safety of Darcet developed (1775) an alloy 1794), who had witnessed some of the National Convention charged the made of three part of tin, eight of the preceding experiments and three with “de faire des expériences sur bismuth, and five of lead that was found them quite relevant to the l’union de différentes espèces liquid at the temperature of boiling work he was doing on the causes and d’huiles et de graisses avec la soude, water and latter found use in the pro- agents of combustion, invited Louis- de faire connoître au comité les duction of stereotype plates (Note Claude Cadet de Gassicourt (1731- savons qui résultent de ces combi- 3).25 Further work on alloys, some in 1799) and Macquer to assist him in naisons, leur nature, leur qualité, collaboration with Bertrand. Pelle- performing more experimental etc.” (charged with the task of per- tier (1761-1797), his assistant and work. Their experimental set up was forming experiments on the union demonstrateur at the Collége de now provided with the necessary of different kinds of oils and fats France, enabled Darcet to develop a ancillaries to permit collection of the with soda in order make known to method of separating the copper possible gases released, either by the committee the soaps that re- from church bells and show how distillation or by sublimation in the sulted from the combinations, their these could be melted down to cast cooler parts of the apparatus. They nature, their quality, etc.). The first cannon. In order to try to solve the were, however, unable to detect any part of the report described the monetary deficit, the Assemblée product.20 When the diamond was sources, methods of preparation, Nationale Constituante decreed in burnt in a closed vessel by means of and characteristics of the raw mate- 1789 that all the ecclesiastical prop- the glass in the apparatus designed rials required (sodium hydroxide, erty should be put at the disposition by Lavoisier, it was found that a part potassium hydroxide, calcium hy- of the Nation; as a consequence of the air in the vessel was used up droxide, and oils), as well as the many churches fell in disuse and a as was the case with other combus- equipment necessary for the differ- large number of bells came into the tible bodies, and when lime was sub- ent operations. This was followed by market and with them the interest sequently added it turned milky and procedures for the preparation of in the large quantity of copper avail- deposited a precipitate.21 When a dia- soda and causticized lye, the appa- able in the form of bell metal, an al-

3. The name fusible metals is now applied to a variety of alloys, usually composed of bismuth, lead, and tin, which possess the property of melting at comparatively low temperatures, (between 91 to 95 0C). Variation of the proportion of the components can also lead to melting temperatures above that of boiling water. The addition of cadmium or mercury reduces the melting point further. Fusible metals have the additional property of expanding as they cool, for this reason they may be used for taking casts of anatomical specimens or making clichés from wood blocks. High melting fusible metals are used for making the fusible plugs inserted in the crown of steam boilers, as a safeguard in the event of the water level falling too low. In automatic fire sprinklers the orifices of the pipes are closed with fusible metal, which melts and liberates the water when the temperature in the rook rises about a predetermined limit. 109 Revista CENIC Ciencias Químicas, Vol. 35, No. 2, 2004.

loy containing 20 to 25 % of tin. Sev- recommended: “Nous pensons qu’il 11. Darcet J. Rapport sur l’Électricité Dans eral possibilities were considered for faut soumettre cette théorie nouvelle les Maladies Nerveuses, Paris, 1785. their use: to sell them as such, to (la chimie pneumatique) ainsi que sa 12. Lelièvre C.H., Darcet J., Giroud A. separate the components, or to alloy nomenclature, à l’épreuve du temps, Rapport sur les Divers Moyens d’Extraire Avec Avantage le Sel de them with a certain amount of cop- au dire des expériences, au balance- Soude du Sel Marin, De l’Imprimerie per in order to make them ductile ment des opinions qui en est la sui- du Comité de Salut Public, Paris, enough so that they could be used vre; enfin au jugement du public 1795. Published also in Ann. Chim., to manufacture cannons, coins, or comme au seul tribunal d’où elles 19 (1797) 58-156. statues. Darcet in collaboration with doivent et puissent ressortir. Alors ce 13. Fourcroy A., Darcet J., Guyton de Pelletier, and Fourcroy made the ne sera plus une théorie, cela devien- Morveau L.B. Rapport Sur les most important contributions to the dra un enchaînement de vérités, ou Couleurs Pour la Porcelaine, De subject.26 Darcet and Pelletier’s une erreur. Dans le premiere cas, elle l’Imprimerie du Comité de Salut method was based on the oxidation donnera une base solide de plus aux Public, Paris, 1779. of the bell alloy with manganese ox- connaissances humaines, dans le se- 14. Darcet J. L’Ètat Actuel des Montag- nes des Pyrénées et les Causes de ide, which attacked the tin before the cond, ell rentrera dans l’oubli avec leur Dégradation, J. Phys., 8, 403-425, copper and gave a good yield. toutes les théories et les systèmes de 1776. 27 Fourcroy’s approach was in two dif- physique qui l’ont precede” (We 15. Darcet J. Mémoire sur le Diamant et ferent directions, based on the vari- believe necessary to subject this new Quelques Autres Pierres Précieuses, able affinity that oxygen has for theory, as well as its nomenclature, Hist. Acad. Royale de Sciences, 1771. metals. In one of them, the bell metal to the test of time, to the experi- 16. Macquer P.J. Dictionnaire de Chymie, was heated it in a crucible in the ments, to the doubts it has raised, in Lacombe, Paris; Vol. 1, 499-524, 1766. presence of air until the increase in short, to the judgment of the public 17. Newton I. Opticks, London, 1730. Re- weight showed that sufficient oxy- as the only tribunal. Then it will not published by Dover Publications, New York, 1952; Book II, Proposition X. gen had been absorbed to convert all be a theory; it will become a chain of 18. Rouelle G.F., Darcet J. Procés-verbal des the tin into oxide, followed by heat- facts or an error. In the first case it Expériences Faites Dans le Laboratoire ing the molten metal in a closed cru- will provide a solid base for solid de M. Rouelle, Sur Plusieurs Diamans cible, avoiding the possibility of fur- human knowledge; in the second & Pierres, Paris, 1772. ther absorption of oxygen. During case, it will go into oblivion with all 19. Rouelle G.F., Darcet J. Expériences this second heating stage the copper other theories and systems that have Nouvelles sur la Destruction du oxide was reduced by the unreacted preceded it). Diamant, Hist. Acad. Royale de Sci- tin and at the end of the reaction all ences, 1773. the tin was oxidized and could be BIBLIOGRAPHY 20. Lavoisier A.L. Premier Mémoire Sur la Destruction du Diamant Par le Feu, separated from the molten copper. 1. Cuvier G., Notice Historique Sur Mém. Acad. Royale Sci., Part II, 564- Fourcroy’s second approach was Jean Darcet, Mémoirs de l’Institut, 591, 1772. based on the oxidation of the tin by 4, 74-88, 1801. 21. Lavoisier, A. L., Second Mémoire Sur heating the alloy with certain metal- 2. Cuvier G., Éloge Historique de Jean la Destruction du Diamant Par le Feu, lic oxides; he achieved good separa- Darcet, Recueil des Éloges Histori- Mém. Acad. Royale Sci., Part II, 591- tion with black oxide of manganese ques, I, 165-185, 1819. 616, 1772. but litharge and oxide of arsenic 3. Coleby L.J.M. The Chemical Studies 22. De Montigny T., Macquer P.J., Cadet of P. J. Macquer, George Allen & were found to be unsatisfactory. L.C., Lavoisier A.J. Premier Essai du Unwin, London, 1938. Grand Verre Ardent de Mr. Trudaine As a result, in 1793, when large 4. Cuzacq R. Le Chimiste Jean Darcet Établi au Jardin de l’Infante au Com- quantities of copper were urgently et sa Famille, Editions Jean-Lacoste, mencement du Mois d’Octobre de needed for manufacturing cannon, Mont-de-Marsan, 1955. l’Année 1774, Mém. Acad. Royale the Committee of Public Safety de- 5. Wisniak J. Guillaume-François Rouelle, Sci., 62-72, 1774. creed the destruction of all church Educ. Quím., submitted (2004). 23. Dizé M. J.J. Précis Historique Sur la bells. Instructions describing both 6. Gillispie C.C. Science and Polity in Vie et les Travaux de Jean Darcet, Pelletier’s and Fourcroy’s methods France at the End of the Old Regime, Gillé, Paris, 1801. Princeton University Press: Princ- were published in detail and both 24. Darcet. J., Lelièvre C.H., Pelletier B. eton, 1980. Rapport sur la Fabrication des were recommended. Fourcroy’s pro- 7. Darcet J. Mémoire sur la Action d’un Savons, sur leurs Différentes cedure proved to be cheaper, al- Feu Égal, Violent et Continué Pendant Espècer, Suivant la Nature des though both helped provide copper Plusieurs Jours, sur un Grand Nombre Huiles et des Alkalis qu’on Employe to the revolutionary government de Terres, de Pierres et de Chaux Pour les Fabriquer; et sur les Moyens during the many wars it held during Métalliques, Hist. Acad. Royale de Sci- d’en Préparer Par-Tout, Avec les its existence. ences, 75, 1766; also published as a book Diverses Matières Huileuses et (P. G. Cavelier, Paris, 1766). Alkalines, Ann. Chim., 19, 253-354, 6. Miscellaneous 8. Darcet J. Second Mémoire sur la Ac- 1797. tion d’un Feu Égal, Violent et 25. Darcet J. Expériences sur l’Alliage The logical reform of the Continué Pendant Plusieurs Jours, Fusible de Plomb, de Bismuth et chemical language proposed by La- sur un Grand Nombre de Terres, de d’Étain, Hist. Acad. Royale de Sci- voisier, Fourcroy, Berthollet, and Pierres et de Chaux Métalliques, ences, 1775. Guyton de Morveau, did not gain a Hist. Acad. Royale de Sciences, 1771. 26. Pelletier B., Darcet J. Instruction sur complete approval of the referees 9. Pott J.H. Fortsetzung Derer Chy- l’Art de Séparer le Cuivre du Métal appointed by the Académie des mischen Untersuchungen Welche von des Cloches. Publié par Ordre du Sciences in 1787, Antoine Baumé der Lithogeognosie, Oder Erkäntniss Comité de Salut Public, De und Bearbeitung derer Steine und (1728-1804), Louis-Claude Cadet de l’Imprimerie du Comité de Salut Erden Specieller Handeln, Christian Public, Paris, 1794. Gassicourt (1731-1799), Darcet, and Friedrich Voss, Potsdamm, 1746. 27. Fourcroy A.F. Recherches Sur le Balthazar-Georges Sage (1740-1824). 10. Darcet J. Mémoire sur la Calcination Métal des Cloches, et Sur les Moyens The three were supporters of the de la Pierre Calcaire et sur sa Vitrifi- d’en Séparer le Cuivre, Ann. Chim., phlogiston theory and hence they cation, Paris, 1783. 9, 305-352, 1791. 110