Dec 172016


Today is the birthday (1778) of Sir Humphry Davy, 1st Baronet PRS MRIA FGS, a Cornish chemist and inventor whom I remember chiefly as the inventor of the Davy safety lamp for miners, but who had an illustrious career as a chemist.  He isolated a series of elements for the first time – potassium, sodium,  calcium, strontium, barium, magnesium and boron, as well as discovering the elemental nature of chlorine and iodine. He also studied the forces involved in these separations, inventing the new field of electrochemistry. Besides the Davy Lamp he invented a very early form of the incandescent light bulb.

Davy was born in Penzance in Cornwall but his family moved to Varfell, near Ludgvan, when he was 9, and in term-time Davy boarded with John Tonkin, his mother’s godfather. After Davy’s father died in 1794, Tonkin apprenticed him to John Bingham Borlase, a surgeon with a practice in Penzance. In the apothecary’s dispensary, Davy became a chemist, and he conducted his earliest chemical experiments in a garret in Tonkin’s house. Davy’s friends said: “This boy Humphry is incorrigible. He will blow us all into the air.” His elder sister complained of the ravages made on her dresses by corrosive substances.

His Quaker friend and mentor Robert Dunkin remarked: ‘I tell thee what, Humphry, thou art the most quibbling hand at a dispute I ever met with in my life.’ One winter day he took Davy to a river to show him that rubbing two plates of ice together developed sufficient energy by motion, to melt them, and that after the motion was suspended, the pieces were united by regelation. Later, as professor at the Royal Institution, Davy repeated many of the ingenious experiments he learned from Dunkin.

Through a mutual friend he met Dr Edwards who was a lecturer in chemistry at St. Bartholomew’s Hospital (Barts). He permitted Davy to use his laboratory and possibly directed his attention to the floodgates of the port of Hayle, which were rapidly decaying as a result of the contact between copper and iron under the influence of seawater. Galvanic corrosion was not understood at that time, but the phenomenon prepared Davy for subsequent experiments on ship’s copper sheathing.

Thomas Beddoes and John Hailstone were engaged in a geological controversy on the rival merits of the Plutonian and Neptunist hypotheses. They traveled together to examine the Cornish coast for evidence of their competing theories and made Davy’s acquaintance. Beddoes, who had established at Bristol a ‘Pneumatic Institution,’ needed an assistant to superintend the laboratory. After prolonged negotiations, mainly by Gilbert, Mrs Davy and Borlase consented to Davy’s departure, but Tonkin wished him to remain in his native town as a surgeon, and altered his will when he found that Davy insisted on going to Dr Beddoes.On 2 October 1798, Davy joined the Pneumatic Institution at Bristol. It had been established to investigate the medical powers of factitious airs and gases, and Davy was to superintend the various experiments. The arrangement agreed between Dr Beddoes and Davy was liberal and enabled Davy to give up all claims on his paternal property in favor of his mother. He did not intend to abandon the medical profession and was determined to study and graduate at Edinburgh but he soon began to fill parts of the institution with voltaic batteries. While living in Bristol, Davy met the Earl of Durham, who was a resident in the institution for his health and became close friends with Gregory Watt, James Watt, Samuel Taylor Coleridge and Robert Southey, all of whom became regular users of nitrous oxide, to which Davy became addicted.


James Watt built a portable gas chamber to facilitate Davy’s experiments with the inhalation of nitrous oxide. At one point the gas was combined with wine to judge its efficacy as a cure for hangover (his laboratory notebook indicated success). The gas was popular among Davy’s friends and acquaintances, and he noted that it might be useful for performing surgical operations. However, anesthetics were not regularly used in medicine or dentistry until decades after Davy’s death. Davy conducted numerous experiments on himself with nitrous oxide, carbon monoxide, and with respiration at considerable risk.

In 1799, Count Rumford had proposed the establishment in London of an ‘Institution for Diffusing Knowledge’ that is, the Royal Institution. In 1801 Davy left Bristol to take up a new post at the Royal Institution as assistant lecturer in chemistry, director of the chemical laboratory, and assistant editor of the journals of the institution.  On 25 April 1801, Davy gave his first lecture on the relatively new subject of ‘Galvanism’. The first lecture garnered rave reviews, and by the June lecture Davy wrote to John King that his last lecture had attendance of nearly 500 people. “There was Respiration, Nitrous Oxide, and unbounded Applause. Amen!”


Davy’s lectures also included spectacular and sometimes dangerous chemical demonstrations for his audience, a generous helping of references to divine creation, and genuine scientific information. Not only a popular lecturer, the young and handsome Davy acquired a huge female following around London, and nearly half of the attendees pictured in Gillray’s cartoon of the Royal Institution are female. When Davy’s lecture series on Galvanism ended, he progressed to a new series on Agricultural Chemistry, and his popularity continued to skyrocket. By June 1802, after just over a year at the Institution and at the age of 23, Davy was nominated to full lecturer.

In 1802 Davy had what was then the most powerful electrical battery in the world at the Royal Institution. With it, Davy created the first incandescent light by passing electric current through a thin strip of platinum, chosen because the metal had an extremely high melting point. It was neither sufficiently bright nor long lasting enough to be of practical use, but demonstrated the principle. By 1806 he was able to demonstrate a much more powerful form of electric lighting to the Royal Society in London. It was an early form of arc light which produced its illumination from an electric arc created between two charcoal rods.


Davy was a pioneer in the field of electrolysis using the voltaic pile to split common compounds and thus prepare many new elements. He went on to electrolyze molten salts and discovered several new metals, including sodium and potassium. Davy discovered potassium in 1807, deriving it from caustic potash (KOH). Before the 19th century, no distinction had been made between potassium and sodium. Potassium was the first metal that was isolated by electrolysis. Davy isolated sodium in the same year by passing an electric current through molten sodium hydroxide. Davy discovered calcium in 1808 by electrolyzing a mixture of lime and mercuric oxide. He worked with electrolysis throughout his life and was first to isolate magnesium, boron, and barium.

Chlorine was discovered in 1774 by Swedish chemist Carl Wilhelm Scheele, who called it “dephlogisticated marine acid” and mistakenly thought it contained oxygen. Davy showed that the acid of Scheele’s substance, called at the time oxymuriatic acid, contained no oxygen. This discovery overturned Lavoisier’s definition of acids as compounds of oxygen. In 1810, chlorine was given its current name by Humphry Davy, who insisted that chlorine was in fact an element.

Davy later damaged his eyesight in a laboratory accident with nitrogen trichloride. Pierre Louis Dulong first prepared this compound in 1812, and lost two fingers and an eye in two separate explosions with it. Davy’s own accident induced him to hire Michael Faraday as a co-worker.

In 1812, Davy was knighted, gave a farewell lecture to the Royal Institution, and married a wealthy widow, Jane Apreece. (While Davy was generally acknowledged as being faithful to his wife, their relationship was stormy, and in later years he travelled to continental Europe alone.) In October 1813, he and his wife, accompanied by Michael Faraday as his scientific assistant (and valet), travelled to France to collect a medal that Napoleon Bonaparte had awarded Davy for his electro-chemical work. While in Paris, Davy was asked by Gay-Lussac to investigate a mysterious substance isolated by Bernard Courtois. Davy showed it to be an element, which is now called iodine. The party left Paris in December 1813, traveling south to Italy. They stayed a while in Florence, where, in a series of experiments conducted with Faraday’s assistance, Davy succeeded in using the sun’s rays to ignite diamond, proving it is composed of pure carbon.

Davy’s party continued to Rome, and also visited Naples and Mount Vesuvius. By June 1814, they were in Milan, where they met Alessandro Volta, and then continued north to Geneva. They returned to Italy via Munich and Innsbruck, and when their plans to travel to Greece and Istanbul were abandoned after Napoleon’s escape from Elba, they returned to England.


After his return to England in 1815, Davy experimented with lamps for use in coal mines. There had been many mining explosions caused by firedamp or methane often ignited by open flames of the lamps then used by miners. In particular the Felling mine disaster in 1812 near Newcastle caused great loss of life, and action was needed to improve underground lighting and especially the lamps used by miners. Davy conceived of using an iron gauze to enclose a lamp’s flame, and so prevent the methane burning inside the lamp from passing out to the general atmosphere. Although the idea of the safety lamp had already been demonstrated by William Reid Clanny and by the then unknown (but later very famous) engineer George Stephenson, Davy’s use of wire gauze to prevent the spread of flame was used by many other inventors in their later designs. George Stephenson’s lamp was very popular in the north-east coalfields, and used the same principle of preventing the flame reaching the general atmosphere, but by different means. Unfortunately, although the new design of gauze lamp initially did seem to offer protection, it gave much less light, and quickly deteriorated in the wet conditions of most pits. Rusting of the gauze quickly made the lamp unsafe, and the number of deaths from firedamp explosions rose yet further.

There was some discussion as to whether Davy had discovered the principles behind his lamp without the help of the work of Smithson Tennant, but it was generally agreed that the work of both men had been independent. Davy refused to patent the lamp, and its invention led to his being awarded the Rumford medal in 1816.

In January 1819, Davy was awarded a baronetcy. Although Sir Francis Bacon and Sir Isaac Newton had already been knighted, this was, at the time, the first such honor ever conferred on a man of science in Britain. A year later he became President of the Royal Society. Davy’s laboratory assistant, Michael Faraday, went on to enhance Davy’s work and would become the more famous and influential scientist. Davy is supposed to have even claimed Faraday as his greatest discovery. Davy later accused Faraday of plagiarism, however, causing Faraday (the first Fullerian Professor of Chemistry) to cease all research in electromagnetism until his mentor’s death.


Davy spent the last months of his life writing Consolations in Travel, an immensely popular, somewhat freeform compendium of poetry, thoughts on science and philosophy. Published posthumously, the work became a staple of both scientific and family libraries for several decades afterward. Davy spent the winter in Rome, hunting in the Campagna on his 50th birthday. But on 20 February 1829 he had a stroke. After spending many months attempting to recuperate, Davy died in a hotel room in Geneva on 29 May 1829.

He had wished to be buried where he died, but had also wanted the burial delayed in case he was only comatose. He refused to allow a post-mortem for similar reasons. But the laws of Geneva did not allow any delay and he was given a public funeral on the following Monday, in the Plainpalais Cemetery, outside the city walls. Jane organized a memorial tablet for him, in Westminster Abbey shortly afterwards.


In the spirit of Davy’s experiments the Royal Institution’s website gives a recipe for microwave cupcakes (or mug cakes) and suggests ways to experiment, Here’s the basic recipe slightly edited.  The point is to make the original first, and then play around with the ingredients and see what happens. RI asks the following questions:

What do you think will happen if we don’t include the egg?

How could we find out?

What do you think will happen if we don’t include the oil?

What do you think will happen if we don’t include the baking


Microwave Mug Cake


4 tbsp plain flour
2 tbsp caster sugar
¼ tsp baking powder
1 small/medium egg
2 tbsp vegetable oil
2 tbsp water


Mix all the dry ingredients together in a mug

Break the egg into the mug and add the oil and water

Stir vigorously with a fork

Zap the resulting mixture in your microwave at full power for 2 minutes


Nov 112016


Today is possibly the birthday in 1493 (or possibly 17th December) of Philippus Aureolus Theophrastus Bombastus von Hohenheim, known to history as Paracelsus, a Swiss German philosopher, physician, botanist, astrologer, and general occultist. He is credited with a lot of things that he probably does not deserve, such as being the founder of toxicology. He is usually fairly credited with giving zinc its name, calling it zincum. Paracelsus’ most important legacy is undoubtedly his critique of scholasticism in medicine, science, and theology – the idea that all previously acknowledged authorities must be revered and built upon rather than challenged. Paracelsus was quite happy to discard texts he deemed worthless – pure heresy in his time. Most of his theoretical work does not withstand modern scientific scrutiny, but his general insights helped revolutionize scientific methods over time.

Paracelsus was born and raised in the village of Einsiedeln in Switzerland. His father, Wilhelm Bombast von Hohenheim, was a Swabian (German) chemist and physician. His mother was Swiss and probably a bondswoman of the abbey of Einsiedeln in Switzerland where he was born. She is believed to have died in his childhood. In 1502 the family moved to Villach in Carinthia where Paracelsus’ father worked as a physician, attending to the medical needs of the pilgrims and inhabitants of the cloister.

Paracelsus was educated by his father in botany, medicine, mineralogy, mining, and natural philosophy. He also received a humanistic and theological education from local clerics and the convent school of St. Paul’s Abbey in the Lavanttal. At the age of 16 he started studying medicine at the University of Basel, later moving to Vienna. He gained his doctorate degree from the University of Ferrara in 1515 or 1516.


He was employed as a military surgeon in the Venetian service in 1522. Paracelsus appears to have been very well traveled, so it is probable that he was involved in the many wars waged between 1517 and 1524 in Holland, Scandinavia, Prussia, Tartary, the countries under Venetian influence, and possibly the near East. His wanderings as an itinerant physician and sometime journeyman miner took him through Germany, France, Spain, Hungary, the Netherlands, Denmark, Sweden, Poland and Russia.

Paracelsus was well known as a difficult man. He gained a reputation for being arrogant and soon garnered the anger of other physicians in Europe. Some even claim he was a habitual drinker. He was prone to many outbursts of abusive language, abhorred untested theory, and ridiculed anybody who placed more importance on titles than practice (‘if disease put us to the test, all our splendor, title, ring, and name will be as much help as a horse’s tail’). During his time as a professor at University of Basel, he invited barber-surgeons, alchemists, apothecaries, and others lacking academic background to serve as examples of his belief that only those who practiced an art knew it: ‘The patients are your textbook, the sickbed is your study.’ He held the chair of medicine at the University of Basel and city physician for less than a year. He angered his colleagues by lecturing in German instead of Latin in order to make medical knowledge more accessible to the common people. He is credited as the first to do so. He was the first to publicly condemn the medical authority of Avicenna and Galen and threw their writings into a bonfire on St. John’s Day in 1527.


In 1526 he bought the rights of citizenship in Strasbourg to establish his own practice. But soon after he was called to Basel to the sickbed of Johann Froben or Frobenius, a successful printer and publisher. Based on historical accounts, Paracelsus cured Frobenius. During that time, the Dutch Renaissance humanist Erasmus von Rotterdam, also at the University of Basel, witnessed the medical skills of Paracelsus, and the two scholars initiated a dialogue by letter on medical and theological subjects.

He was a contemporary of Copernicus, Leonardo da Vinci and Martin Luther. During his life, he was compared with Luther partly because his ideas were different from the mainstream and partly because of openly defiant acts against the existing authorities in medicine. This act struck people as similar to Luther’s defiance of the Catholic Church. Paracelsus rejected that comparison. Famously Paracelsus said, “I leave it to Luther to defend what he says and I will be responsible for what I say. That which you wish to Luther, you wish also to me: You wish us both in the fire.”


After slandering his opponents with vicious epithets due to a dispute over a physician’s fee, Paracelsus had to leave Basel secretly fearing punishment by the court. He became a tramp, wandering through Central Europe again. Around 1529, he officially adopted the name Paracelsus which is presumed to mean “surpassing Celsus,” the Roman writer on medicine, although, I suppose, it could also be “like Celsus” in that they both made novel contributions (“para” can mean “enlarge” in late Latin). In 1530, at the instigation of the medical faculty at the University of Leipzig, the city council of Nürnberg prohibited the printing of Paracelsus’ works. He revised old manuscripts and wrote new ones but had trouble finding publishers. In 1536, his Die grosse Wundartznei (“The Great Surgery Book”) was published and enabled him to regain fame.

He died at the age of 47 in Salzburg, and his remains were buried according to his wishes in the cemetery at the church of St. Sebastian in Salzburg. His remains are now located in a tomb in the porch of that church. After his death, the movement of Paracelsianism was seized upon by many wishing to subvert the traditional Galenic physics, and his therapies became more widely known and used. Most of Paracelsus’ writings were published after his death and still much controversy prevailed. He was accused of leading “a legion of homicide physicians” and his books were called “heretical and scandalous”. However, after many decades in 1618, a new pharmacopeia by the Royal College of Physicians in London included Paracelsian remedies.

His motto was “Alterius non sit qui suus esse potest” (“Let no man belong to another who can belong to himself.”)


Paracelsus was one of the first medical professionals to recognize that physicians required a solid academic knowledge in the natural sciences, especially chemistry. Paracelsus pioneered the use of chemicals and minerals in medicine although his ideas were not useful. From his study of the elements as they were conceived in his time (earth, water, fire, and air), Paracelsus adopted a tripartite alternative to explain the nature of medicine: sulphur, mercury,  and salt. He mentions the model first in Opus paramirum dating to about 1530. Paracelsus believed that the principles sulphur, mercury, and salt contained the poisons contributing to all diseases. He saw each disease as having three separate cures depending on how it was afflicted, either being caused by the poisoning of sulphur, mercury, or salt. Paracelsus drew the importance of sulphur, salt and mercury from medieval alchemy, where they all occupied a prominent place. He demonstrated his theory by burning a piece of wood. The fire was the work of sulphur, the smoke was mercury, and the residual ash was salt. Paracelsus also believed that mercury, sulphur, and salt provided a good explanation for the nature of medicine because each of these properties existed in many physical forms. The tria prima also defined human identity. Sulphur embodied the soul, (the emotions and desires); salt represented the body; mercury epitomized the spirit (imagination, moral judgment, and the higher mental faculties). By understanding the chemical nature of the tria prima, a physician could discover the means of curing disease. With every disease, the symptoms depended on which of the three principals caused the ailment. Paracelsus theorized that materials which are poisonous in large doses may be curative in small doses (one of the few things he got right).


His alchemical views led him to believe that sickness and health in the body relied on the harmony of Human (microcosm) and Nature (macrocosm). He believed that humans must have certain balances of minerals in their bodies, and that certain illnesses of the body had chemical remedies that could cure them. As a result of this hermetical idea of harmony, the universe’s macrocosm was represented in every person as a microcosm. An example of this correspondence is the doctrine of signatures used to identify curative powers of plants. If a plant looked like a part of the body, then this signified its ability to cure this given anatomy. Therefore, the root of the orchid looks like a testicle and can therefore heal any testicle associated illness. Paracelsus also suggested that just as humans can ward off the influence of evil spirits with morality, they can also ward off diseases with good health.

Paracelsus believed that true anatomy could only be understood once the nourishment for each part of the body was discovered. He believed that therefore, one must know the influence of the stars on these particular body parts. Diseases were caused by poisons brought from the stars. However, ‘poisons’ were not necessarily something negative, in part because related substances interacted, but also because only the dose determined if a substance was poisonous or not. Paracelsus further claimed that like cures like. If a star or poison caused a disease, then it must be countered by another star or poison. Paracelsus viewed the universe as one coherent organism pervaded by a uniting lifegiving spirit, and this in its entirety, humanity included, was God. His views put him at odds with the Church which saw a necessary difference between the Creator and the created.


His work Die große Wundarzney is a forerunner of antisepsis. This specific empirical knowledge originated from his personal experiences as an army physician in the Venetian wars. Paracelsus demanded that the application of cow dung, feathers and other obnoxious concoctions to wounds be stopped in favor of keeping the wounds clean, saying, “If you prevent infection, Nature will heal the wound all by herself.” During his time as a military surgeon, Paracelsus was exposed to the crudity of medical knowledge at the time, when doctors believed that infection was a natural part of the healing process. He advocated for cleanliness and protection of wounds, as well as the regulation of diet.

One of his most overlooked achievements was the systematic study of minerals and the curative powers of alpine mineral springs. His countless wanderings also brought him deep into many areas of the Alps, where such therapies were already practiced on a less common scale than today. Paracelsus’ major work On the Miners’ Sickness and Other Diseases of Miners documented the occupational hazards of metalworking, and included treatment and prevention strategies.


Paracelsus is credited with providing the first clinical/scientific mention of the unconscious. In his work Von den Krankeiten he writes: “Thus, the cause of the disease chorea lasciva is a mere opinion and idea, assumed by imagination, affecting those who believe in such a thing. This opinion and idea are the origin of the disease both in children and adults. In children the case is also imagination, based not on thinking but on perceiving, because they have heard or seen something. The reason is this: their sight and hearing are so strong that unconsciously they have fantasies about what they have seen or heard.” Paracelsus also called for the humane treatment of the mentally ill although he was ignored for several centuries. He saw them not to be possessed by evil spirits, but merely “brothers ensnared in a treatable malady.”

Paracelsus’ home of Einsiedeln is in Schwyz canton, which gives Switzerland its name. Älplermagronen is a popular and traditional recipe from the region. It’s basically pasta and potatoes baked in a creamy cheese sauce and served with hot apple sauce. I’m not sure how healthy it is, but in small doses should be all right.




1 lb potatoes, peeled and cut into cubes
1 lb penne pasta
2 large onions, peeled and sliced
4 tbsp butter or oil
1 cup grated melting cheese (Gruyère, Appenzeller, Raclette)
½ cup cream
salt and pepper to taste
apple sauce


Heat oven to 375° F.

Cook the potatoes and pasta separately until they are al dente. Drain and reserve.

Heat the butter or oil over medium-low heat in a frying pan, add the onions and sauté them until they are golden brown.

Mix the pasta, potatoes, and cheese together and place in a casserole dish. Pour the cream over the dish and spread the browned onions on top. Season to taste with freshly ground pepper and salt.

Bake covered for 10-15 minutes until the dish is hot and the cheese is melted. Serve with warmed applesauce.

Aug 262013


Today is the birthday (1743) of Antoine-Laurent de Lavoisier, a French nobleman whose work in chemistry had a major influence on the nature of scientific inquiry.   Lavoisier is most noted for his discovery of the role oxygen plays in combustion. He recognized and named oxygen (1778) and hydrogen (1783), helped construct the metric system, wrote the first extensive list of elements, and helped to reform chemical nomenclature. He predicted the existence of silicon (1787) and was also the first to establish that sulfur was an element (1777) rather than a compound. He discovered that, although matter may change its form or shape, its mass always remains the same. In the interest of “full disclosure” let me say that I admire his work greatly, but I also lament the fact that the revolution in science he helped usher in has also ushered in an era in which many people believe that if something cannot be measured it is not real.  We have him to thank for the disenchantment of the Western world.


Lavoisier was born to a wealthy family in Paris, the son of an attorney at the Parlement de Paris. He inherited a large fortune at the age of five with the death of his mother. Lavoisier began his schooling at the Collège des Quatre-Nations (known as the Collège Mazarin) in Paris in 1754 at the age of 11. In his last two years (1760-1761) at the college his scientific interests were aroused, and he studied chemistry, botany, astronomy, and mathematics. In philosophy he was taught by Abbé Nicolas Louis de Lacaille, a distinguished mathematician and observational astronomer who imbued the young Lavoisier with an interest in meteorological observation. He also studied law and received a licentiate, but never practiced law.

Lavoisier’s devotion and passion for chemistry were largely influenced by Étienne Condillac, a prominent French scholar of the 18th century. From 1763 to 1767, he studied geology under Jean-Étienne Guettard. In collaboration with Guettard, Lavoisier worked on a geological survey of Alsace-Lorraine in June 1767. In 1764 he read his first paper to l’Académie Royale des Sciences (Royal Academy of Sciences), France’s elite scientific society, on the chemical and physical properties of gypsum (hydrated calcium sulfate), and in 1766 he was awarded a gold medal by the King for an essay on the problems of urban street lighting. In 1768 Lavoisier received a provisional appointment to l’Académie Royale des Sciences. In 1769, he worked on the first geological map of France.

At age 26, around the time he was elected to l’Académie, Lavoisier bought a share in the Ferme Générale, a tax farming financial company which advanced the estimated tax revenue to the royal government in return for the right to collect the taxes. Lavoisier attempted to introduce reforms in the French monetary and taxation system to help the poor. While in government work, he helped develop the metric system to secure uniformity of weights and measures throughout France. Lavoisier consolidated his social and economic position when, in 1771 at age 28, he married Marie-Anne Pierrette Paulze, the 13-year-old daughter of a senior member of the Ferme Générale. She was to play an important part in Lavoisier’s scientific career—notably, she translated English documents for him, including Richard Kirwan’s Essay on Phlogiston and Joseph Priestley’s research. In addition, she assisted him in the laboratory and created many sketches and carved engravings of the laboratory instruments used by Lavoisier and his colleagues for their scientific works.

lavoisier2  Lavoisier_decomposition_air

Lavoisier demonstrated with careful measurements that transmutation of water to earth (conceived of at the time as elements) was not possible. He burnt phosphorus and sulfur in air, and proved that the products weighed more than the original. Nevertheless, the weight gained was lost from the air. Thus, in 1789, he established the Law of Conservation of Mass, which is also sometimes called “Lavoisier’s Law.”

Repeating the experiments of Priestley, he demonstrated that air is composed of two parts, one of which combines with metals to form calxes (oxides). In Considérations Générales sur la Nature des Acides (1778), he demonstrated that the “air” (gas) responsible for combustion was also the source of acidity. The next year, he named this portion “oxygen” (Greek for “acid-former”), and the other “azote” (Greek for “no life”). Lavoisier thus has a claim to the discovery of oxygen along with Joseph Priestley and Carl Wilhelm Scheele. He also discovered that the “inflammable air” discovered by Cavendish — which he termed “hydrogen” (Greek for water-former) — combined with oxygen to produce a dew, as Priestley had reported, which appeared to be water. In Reflexions sur le Phlogistique (1783), Lavoisier showed the prevailing phlogiston theory of combustion (that there was an element called phlogiston that was responsible for burning) was untenable.


Lavoisier worked with Claude Louis Berthollet and others to devise a system of chemical nomenclature which serves as the basis of the modern system of naming chemical compounds. In his  Méthode de nomenclature chimique (Methods of Chemical Nomenclature) (1787), Lavoisier invented the system of naming and classification still largely in use today, including names such as sulfuric acid, sulfates, and sulfites.


Lavoisier’s Traité Élémentaire de Chimie (Elementary Treatise on Chemistry, 1789) was the first modern chemistry textbook, and presented a unified view of new theories of chemistry, contained a clear statement of the Law of Conservation of Mass, and denied the existence of phlogiston. In addition, it contained a list of elements, or substances that could not be broken down further, which included oxygen, nitrogen, hydrogen, phosphorus, mercury, zinc, and sulfur. His list, however, also included light, and caloric, which he believed to be material substances. In the work, Lavoisier underscored the observational basis of his chemistry, stating “I have tried…to arrive at the truth by linking up facts; to suppress as much as possible the use of reasoning, which is often an unreliable instrument which deceives us, in order to follow as much as possible the torch of observation and of experiment.” Nevertheless, he believed that the real existence of atoms was philosophically impossible.


With Pierre-Simon Laplace, Lavoisier used a calorimeter to estimate the heat given off per unit of carbon dioxide produced. They found the same ratio for a flame and animals, indicating that animals produced energy by a type of combustion. Lavoisier believed in the radical theory, believing that radicals, which function as a single group in a chemical reaction, would combine with oxygen in reactions. He believed all acids contained oxygen (later proven wrong). He also discovered that diamond is a crystalline form of carbon. Lavoisier made many fundamental contributions to the science of chemistry. Following Lavoisier’s work, chemistry acquired a strict quantitative nature, allowing reliable predictions to be made. The revolution in chemistry which he brought about was a result of a conscious effort to fit all experiments into the framework of a single theory.

As the French Revolution gained momentum from 1789 on, Lavoisier’s world inexorably collapsed around him. Attacks mounted on the deeply unpopular Ferme Générale, and it was eventually suppressed in 1791. In 1792 Lavoisier was forced to resign from his post on the Gunpowder Commission and to move from his house and laboratory at the Royal Arsenal. On August 8, 1793, all the learned societies, including the l’Académie Royale des Sciences, were suppressed.

He tried to remain aloof from the political arena, no doubt fearful and uncomprehending of the violence he saw. However, on Nov. 24, 1793, the arrest of all the former tax gatherers was ordered. He was branded a traitor by the Convention under Maximilien de Robespierre during the Reign of Terror, in 1794. Lavoisier and the other former tax gatherers were formally brought to trial on May 8, 1794. Lavoisier was convicted with summary justice of having plundered the people and the treasury of France, of having adulterated the nation’s tobacco with water, and of having supplied the enemies of France with huge sums of money from the national treasury. Lavoisier, along with 27 of his former colleagues, was guillotined on the same day. Lavoisier’s importance to science was expressed by Joseph Louis Lagrange who lamented the beheading by saying: “Il ne leur a fallu qu’un moment pour faire tomber cette tête, et cent années peut-être ne suffiront pas pour en reproduire une semblable.” (“It took them only an instant to cut off this head, and one hundred years might not suffice to reproduce its like.”)  He was exonerated 18 months later.

I was very fond of chemistry as a boy (my father was a chemistry teacher), and for several years I had a chemistry lab in my bedroom.  It came as a great revelation to me when I was working in the kitchen with my mother, baking a cake, when she explained that once the baking powder was added to the mix you had to work quickly because moistening the powder set off a chemical reaction (an acid plus a carbonate producing carbon dioxide) that would cause the cake to rise, but would peter out if you waited too long before baking. Who knew?  Since then I have always applied my knowledge of chemistry to cooking in one way or another.  For example, red cabbage has a tendency to turn blue when heated because the heat increases alkalinity in the cabbage.  Solution – add an acid (such as vinegar) during the cooking process and the cabbage stays red.

Let’s use one of the best understood chemical processes in cooking, the Maillard reaction, to make a stew.  The Maillard reaction is a non-enzymatic process of browning that is essential to so much cooking. The browning of old, or peeled, fruits and vegetables is caused by enzymes; browning meat and vegetables by frying or baking is not.  The Maillard reaction (browning) occurs when heat is applied to a combination of amino acids and reducing sugars (chemical components of meats and vegetables).  I choose this as a tribute to Lavoisier because oxygen in the molecules plays a key role (“redox” for those who know some chemistry), in browning (and also in the production of flavor changes). In this recipe I am not using any aromatics such as parsley or thyme because I want the Maillard reaction to speak for itself.


Tío Juan’s Classic Beef Stew ©

2 lbs (1 kilo) stewing beef
1 onion peeled and coarsely chopped
1 ½ lbs (750 g) potatoes
1 lb (500 g) carrots peeled and diced
½ lb (250 g) mushrooms (halved or quartered depending on size)
1 leek chopped
2 cloves of garlic minced fine
4 tbsps extra virgin olive oil
2 pints (9.5 dl) water
1 tbsp butter
1 tbsp flour
salt to taste


I use a heavy, large, well seasoned cast iron skillet for this dish – my single most important pan in the kitchen (in fact, I have two). Use a large skillet or heavy pot. For the browning, use as little oil as needed to prevent sticking. My quantities are for a large skillet.

Put one tablespoon of olive oil in your pot, and heat on medium low heat.  Add the onions and leeks. Cook slowly, stirring occasionally, until the onions and leeks are caramel colored. In the last minute or two add the garlic, but do not let it brown.  The Maillard reaction makes garlic bitter. Set aside in a large bowl.

Raise the temperature to medium high. Add another tablespoon of olive oil. Sauté the carrots quickly until they are browning but not burnt. Set aside with the onions and leeks.

Peel and dice the potatoes. (Doing this ahead of time will cause them to brown by an enzymatic action, NOT the Maillard reaction.  You can prevent browning by placing cut potatoes in acidulated water, but in this case having the potatoes wet is undesirable.) Cook the potatoes as you did the carrots. Set aside in the vegetable bowl.

Raise the temperature to high. Add another tablespoon of olive oil. Sauté the mushrooms quickly. You must be quick because you want them to brown without overcooking. Set aside with the other vegetables.

Add the last of the olive oil. Quickly brown the meat on all sides.  Make sure the pieces are deeply browned.  Add to the vegetables.

Reduce the heat to medium.  Add the butter and flour to the pan.  Using a wire whisk, stir the melted butter and flour to blend.  Cook this roux slowly, stirring often, until it becomes caramel colored.

Slowly add the water to the roux whisking constantly. It will be very thick at first but if you whisk well no lumps will form.

Return the meat and vegetables to the pot, add salt to taste, and simmer until the meat is tender (about 1 hour).  If you want the carrots and potatoes to be firmer, reserve them separately and add them to the pot in the last 20 minutes.

Serve in bowls piping hot with crusty bread (yes, the brown crust is due to the Maillard reaction as well!)

Serves 4

[Re-bloggers note: this recipe is copyright ©Tío Juan.  Use it by all means, but credit me.]