The Revolution of Chemistry
Over the last few centuries the field of chemistry has made great strides. Humans have been experimenting and reaping the benefits of this field for millenniums, yet never had a great understanding it’s fundamentals until the chemical revolution. By the 16th century there had been many advances in the field later to be known as chemistry; smelting and refining of metals, the production of glass ware, pottery and dyes, the development of explosives, artists’ materials, and medicines (Butterfield, 191). Despite the production of these materials, they are not enough to be attributed to a science. As Butterfield suggests, the results of early chemical experiments lacked “adequate intellectual framework which on the one hand embrace the observed data and on the other helps to decide at any moment the direction of the next inquiry” (191). There is no better example of unorganized study than that of alchemy. Although Jensen cites alchemy as being a pillar of modern chemistry, Butterfield suggests it took away from the progression of chemistry into a modern science (191).

To understand modern chemistry, we must first examine the origins of it. One of the key terms in chemistry is “elements.” This term was first used by Plato to describe matter. Soon after, Aristotle summarized the theories of earlier philosophers and developed the view that all substances were made of a primary matter. Aristotle defined an element as “one of those bodies into which other bodies can be decomposed and which itself is not capable of being divided into others.” He took the fundamental properties of all matter, being hotness, coldness, moistness, and dryness. By combining these, he obtained what were called the four elements, fire, air, earth, and water, as shown in this diagram: (public domain)
The theory of the four material elements would continue to be used until the eighteenth century (Partington, 14). Unfortunately, Aristotle’s view of four elements was a “fundamental conclusion of commonsense observation” (Butterfield, 194). As Butterfield suggests, the theory of four elements may have been what caused the chemical revolution to come so late in modern science. For over a thousand years, Aristotle’s view of elements was largely accepted without much thought.

The field of chemistry did not really take off until the seventeenth century with Robert Boyle. According to Partington, Boyle has been named the father of modern chemistry (67). He cites three reasons Boyle is credited with this; Boyle recognized that chemistry is worth studying and not for the sole purpose of aiding medicine or alchemy, he introduced scientific method into chemistry, he gave a clear definition of an element and showed via experiment that the four elements of Aristotle did deserve to be called elements or principles at all, because they could not be extracted from bodies like metals. Of these three reasons, I believe the last two are the most significant reasons why Boyle is the father of modern chemistry. Although he did not have the answers to his inquires surrounding elements, he did recognize that there was something fundamentally wrong with Aristotle’s long-standing view of four elements. Not to be overshadowed by this discovery, Boyle also used rigorous experimental methods in his study. Like Butterfield stated, modern science requires a framework in place to embrace observed data and decide the next inquiry.

Although scientific method was now applied to chemistry, as it had been to physics and astronomy, chemistry faced another setback. This time it was the theory of phlogiston. This theory is credited to start with Johann Becher who published a book in 1669 in which he believed “fatty earth” burned away during combustion (Partington, 85). Georg Ernst Stahl republished Becher’s findings of fatty earth in 1703, and elaborated on his theory. Stahl is credited with coining the term “phlogiston” to describe the element of fatty earth. Stahl believed phlogiston was present in all combustible materials and metals. The reason he believed phlogiston was present in metals was because they could be burnt to calx, similar to what is know named oxides. With what we now know of elements, phlogiston can be difficult to understand by today’s standards. Phlogiston was described as:
…material, sometimes the matter of fire, sometimes a dry earthy substance (soot), sometimes a fatty principle (in sulfur, oils, fats and resins), and sometimes invisible particles emitted by burning a candle. It is contained in animal, vegetable and mineral bodies and is the same in all. It is the cause of metallic properties, of colors, of odors…
In essence, phlogiston was thought to be in all flammable materials. To better understand this, it can be best applied to a candle; when the candle is burned, phlogiston was transferred from it to the surrounding air. When the air became saturated with phlogiston and could contain no more, the flame went out. Breathing was also thought to be a way to remove phlogiston from a body of air. The typical test for the presence of phlogiston was by placing a mouse in an airtight container and measure how long it lived. When the air in the container could accept no more phlogiston, the mouse would die (American Chemical Society, ACS). The theory of phlogiston led chemists in the wrong direction for over one hundred years and can be credited, like Aristotle’s four elements, to a “fundamental conclusion of commonsense observation” (Butterfield, 194).

Building on the scientific method applied to chemistry by Boyle and others since him, Antoine-Laurent Lavoisier would reject the theory of phlogiston and revolutionize chemistry. What helped Lavoisier start the chemical revolution was his use of quantitative methods (Partington, 124). Although he was not the first to apply these methods to chemistry, he was undoubtedly the leader in quantitative chemistry (Ihde, 60). At told by the American Chemical Society (ACS), his attack on the theory of phlogiston began with experiments involving phosphorus and sulfur. Lavoisier was able to show that both elements gained weight when combined with air. Lavoisier was quick to note that this was in contradiction with the theory of phlogiston. He now believed combustion actually involved air, but did not understand how. In 1774 Lavoisier met with English philosopher Joseph Priestley and conducted and experiment burning mercury calx and collected the air from the burn. They noted a candle would burn more vigorously in this collected air. Still believing in phlogiston, and its ability to extinguish flame, Lavoisier named this air “dephlogisticated air.” He continued his experiments with other metal calx (oxides), and eventually concluded air was not a simple substance (ACS). By 1777 Lavoisier proposed a new theory surrounding combustion, excluding the presence of phlogiston. He hypothesized that air contained two components, one part that combined with metal to form calx and was breathable, and the other was neither. Two years later, in 1779, Lavoisier named the breathable air oxygène, or oxygen in English (ACS). He launched a full scale attack on the theory of phlogiston in 1783, calling it a “a veritable Proteus that changes its form every instant.” The theory of phlogiston was soon replaced by Lavoisier’s theory of combustion and oxygen. This is best displayed in the below chart by Jensen which shows the percentage of French chemical literature dealing with phlogiston versus the theory of oxygen:

Lavoisier continued to study the experiments of other scientists, searching for proof of oxygen, and disproving phlogiston. In 1783, he combined oxygen with “inflammable air” creating pure water. He concluded that water was in fact not an element, as Aristotle had hypothesized, but a compound of oxygen and inflammable air, now known to be hydrogen (ACS). Lavoisier now adopted the long ago abandoned theory of elements by Robert Boyle, nearly a century before him.

Partington, Jensen, Ihde, Butterfield and the American Chemical Society credit the revolution in chemistry with Lavoisier’s experiments into combustion using quantitative methods. Although they all agree Lavoisier himself did not conduct all the experiments himself, he had made sense of scattered work of others. Lavoisier was determined “to rid chemistry of every kind of impediment that delays its advance,” and ushered in the modern science of chemistry.

WORKS CITED

Butterfield, Herbert. The Origins of Modern Science: 1300-1800. New York: Free, 1965. Print.

Ihde, Aaron J. The Development of Modern Chemistry. New York: Harper & Row, 1964. Print.

Jensen, William B. "Logic, History, and the Teaching of Chemistry: III. One Chemical Revolution or Three?" Journal of Chemical Education 75.8 (1998): 961-69. Print.

Partington, J. R. A Short History of Chemistry. London: Macmillan, 1960. Print.

American Chemical Society. Antoine-Laurent Lavoisier: The Chemical Revolution. Web. February 26, 2012 <http://portal.acs.org/portal/
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