Question: Which chemical reactions have been known since antiquity?
About the article "Chemical reaction", section "History".

Candidate passages:
The dogs descend from rural shepherd dogs which have been present in the Alps since antiquity. 
Chemical reactions such as combustion in the fire, fermentation and the reduction of ores to metals were known since antiquity.
Initial theories of transformation of materials were developed by Greek philosophers, such as the Four-Element Theory of Empedocles stating that any substance is composed of the four basic elements – fire, water, air and earth.
In the Middle Ages, chemical transformations were studied by Alchemists.
They attempted, in particular, to convert lead into gold, for which purpose they used reactions of lead and lead-copper alloys with sulfur.
The production of chemical substances that do not normally occur in nature has long been tried, such as the synthesis of sulfuric and nitric acids attributed to the controversial alchemist Jābir ibn Hayyān.
The process involved heating of sulfate and nitrate minerals such as copper sulfate, alum and saltpeter.
In the 17th century, Johann Rudolph Glauber produced hydrochloric acid and sodium sulfate by reacting sulfuric acid and sodium chloride.
With the development of the lead chamber process in 1746 and the Leblanc process, allowing large-scale production of sulfuric acid and sodium carbonate, respectively, chemical reactions became implemented into the industry.
Further optimization of sulfuric acid technology resulted in the contact process in 1880s, and the Haber process was developed in 1909–1910 for ammonia synthesis.
From the 16th century, researchers including Jan Baptist van Helmont, Robert Boyle and Isaac Newton tried to establish theories of the experimentally observed chemical transformations.
The phlogiston theory was proposed in 1667 by Johann Joachim Becher.
It postulated the existence of a fire-like element called "phlogiston", which was contained within combustible bodies and released during combustion.
This proved to be false in 1785 by Antoine Lavoisier who found the correct explanation of the combustion as reaction with oxygen from the air.
Joseph Louis Gay-Lussac recognized in 1808 that gases always react in a certain relationship with each other.
Based on this idea and the atomic theory of John Dalton, Joseph Proust had developed the law of definite proportions, which later resulted in the concepts of stoichiometry and chemical equations.
Regarding the organic chemistry, it was long believed that compounds obtained from living organisms were too complex to be obtained synthetically.
According to the concept of vitalism, organic matter was endowed with a "vital force" and distinguished from inorganic materials.
This separation was ended however by the synthesis of urea from inorganic precursors by Friedrich Wöhler in 1828.
Other chemists who brought major contributions to organic chemistry include Alexander William Williamson with his synthesis of ethers and Christopher Kelk Ingold, who, among many discoveries, established the mechanisms of substitution reactions.
A chemical reaction is a process that leads to the transformation of one set of chemical substances to another.
Classically, chemical reactions encompass changes that only involve the positions of electrons in the forming and breaking of chemical bonds between atoms, with no change to the nuclei (no change to the elements present), and can often be described by a chemical equation.
Nuclear chemistry is a sub-discipline of chemistry that involves the chemical reactions of unstable and radioactive elements where both electronic and nuclear changes may both occur.
The substance (or substances) initially involved in a chemical reaction are called reactants or reagents.
Chemical reactions are usually characterized by a chemical change, and they yield one or more products, which usually have properties different from the reactants.
Reactions often consist of a sequence of individual sub-steps, the so-called elementary reactions, and the information on the precise course of action is part of the reaction mechanism.
Chemical reactions are described with chemical equations, which graphically present the starting materials, end products, and sometimes intermediate products and reaction conditions.
Chemical reactions happen at a characteristic reaction rate at a given temperature and chemical concentration, and rapid reactions are often described as spontaneous, requiring no input of extra energy other than thermal energy.
Non-spontaneous reactions run so slowly that they are considered to require the input of some type of additional energy (such as extra heat, light or electricity) in order to proceed to completion (chemical equilibrium) at human time scales.
Different chemical reactions are used in combinations during chemical synthesis in order to obtain a desired product.
In biochemistry, a similar series of chemical reactions form metabolic pathways.
These reactions are often catalyzed by protein enzymes.
These enzymes increase the rates of biochemical reactions, so that metabolic syntheses and decompositions impossible under ordinary conditions may be performed at the temperatures and concentrations present within a cell.
The general concept of a chemical reaction has been extended to non-chemical reactions between entities smaller than atoms, including nuclear reactions, radioactive decays, and reactions between elementary particles as described by quantum field theory. 
Dynamical properties of reaction networks were studied in chemistry and physics after invention of the law of mass action.
The essential steps in this study were introduction of detailed balance for the complex chemical reactions by Rudolf Wegscheider (1901), development of the quantitative theory of chemical chain reactions by Nikolay Semyonov (1934), development of kinetics of catalytic reactions by Cyril Norman Hinshelwood, and many other results.
The mathematical discipline "chemical reaction network theory" was originated by Rutherford Aris, a famous expert in chemical engineering, with support of Clifford Truesdell, the founder and editor-in-chief of the journal "Archive for Rational Mechanics and Analysis".
The paper of R. Aris in this journal was communicated to the journal by C. Truesdell.
It opened the series of papers of other authors (which were communicated already by R Aris).
The well known papers of this series are the works of Frederick J. Krambeck, Roy Jackson, Friedrich Josef Maria Horn, Martin Feinberg and others, published in the 1970s.
In his second "prolegomena" paper, R. Aris mentioned the work of N.Z.
Shapiro, L.S.
Shapley (1965), where an important part of his scientific program was realized.
Since then, the chemical reaction network theory has been further developed by a large number of researchers internationally. 
Enzymes are large biological molecules responsible for the thousands of metabolic processes that sustain life.
They are highly selective catalysts, greatly accelerating both the rate and specificity of metabolic reactions, from the digestion of food to the synthesis of DNA.
Most enzymes are proteins, although some catalytic RNA molecules have been identified.
Enzymes adopt a specific three-dimensional structure, and may employ organic (e.g.
biotin) and inorganic (e.g.
magnesium ion) cofactors to assist in catalysis.
In enzymatic reactions, the molecules at the beginning of the process, called substrates, are converted into different molecules, called products.
Almost all chemical reactions in a biological cell need enzymes in order to occur at rates sufficient for life.
Since enzymes are selective for their substrates and speed up only a few reactions from among many possibilities, the set of enzymes made in a cell determines which metabolic pathways occur in that cell.
Like all catalysts, enzymes work by lowering the activation energy ("E"a‡) for a reaction, thus dramatically increasing the rate of the reaction.
As a result, products are formed faster and reactions reach their equilibrium state more rapidly.
Most enzyme reaction rates are millions of times faster than those of comparable un-catalyzed reactions.
As with all catalysts, enzymes are not consumed by the reactions they catalyze, nor do they alter the equilibrium of these reactions.
However, enzymes do differ from most other catalysts in that they are highly specific for their substrates.
Enzymes are known to catalyze about 4,000 biochemical reactions.
A few RNA molecules called ribozymes also catalyze reactions, with an important example being some parts of the ribosome.
Synthetic molecules called artificial enzymes also display enzyme-like catalysis.
Enzyme activity can be affected by other molecules.
Inhibitors are molecules that decrease enzyme activity; activators are molecules that increase activity.
Many drugs and poisons are enzyme inhibitors.
Activity is also affected by temperature, pressure, chemical environment (e.g., pH), and the concentration of substrate.
Some enzymes are used commercially, for example, in the synthesis of antibiotics.
In addition, some household products use enzymes to speed up biochemical reactions (e.g., enzymes in biological washing powders break down protein or fat stains on clothes; enzymes in meat tenderizers break down proteins into smaller molecules, making the meat easier to chew).