From Alchemy to Chemistry

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From Alchemy to Chemistry

Overview

At the beginning of the seventeenth century, chemistry remained in its infancy. Scientists still had not agreed upon language to describe chemicals and had no ways of classifying them. In addition, chemistry played a role in many different fields that did not necessarily share knowledge with one another: medicine, metallurgy (the science of metals and their uses), pottery making, glass manufacturing, and alchemy. The field that had the most direct impact on the birth of modern chemistry was alchemy. Alchemy was a combination of philosophy, religion, and primitive science whose chief goal was the perfection of matter. This goal included the conversion of metals into gold and the discovery of a potion that would cure all disease. Many scientists of the time viewed chemistry as a pseudo-science much like astrology and palm reading are viewed today. The work of Robert Boyle (1627-1691) helped to change this impression and led to the establishment of chemistry as an independent, modern science.

Background

Throughout the Middle Ages, alchemists tended to cloak their written work in symbolism and secrecy. This was partly due to the religious circumstances of the times. Many faced the threat of the Inquisition if their experiments were looked on unfavorably. The Inquisition was established in the thirteenth century by the Catholic Church to try people who rebelled against religious authority. The punishments of the Inquisition could be severe and even deadly. Another reason for alchemists' secrecy was their fear that any powerful secrets they uncovered might lead to great evil if they fell into the wrong hands. As a result, alchemists used symbols and coded language that made it nearly impossible for an outsider to understand them. For example, mercury is referred to in their writings as green lion, venomous dragon, mother egg, or doorkeeper.

Alchemists believed that all matter was made of the same four elements (earth, air, fire, and water) in different arrangements and proportions. In other words, silver was thought to consist of earth, air, fire, and water as were frogs, bricks, and everything else in the universe. Alchemy consisted of trying to alter the proportions of these elements to make desired substances. According to this idea of matter, every chemical reaction was a kind of transmutation. Transmutation is a change in which one type of matter becomes another. For instance, alchemists believed that lead could be transmuted into gold. (It is now known that transmutation can occur only in special circumstances, such as during some types of radioactive decay.)

One of the first alchemists to break with centuries of secrecy was the German alchemist Andreas Libavius (1540?-1616). In 1597, he published what is considered by some to be the first chemistry textbook. This book summarized the knowledge of the alchemists in clear language that anyone could understand.

Another book, however, was to have an even greater impact on the traditions of alchemy. In 1661, the Irish chemist Robert Boyle (1627-1691) published The Sceptical Chymist. In this book, he opposed the alchemists' theory of the four elements. A central argument that the alchemists presented for this theory was the case of burning wood. The wood gave off fire as it burned. The smoke represented air, and liquid that boiled off the ends of the wood represented water. The ashes left behind were considered earth. In other words, the wood broke down into the four elements of fire, air, water, and earth. Boyle, however, argued that some substances, such as gold and silver, could not be reduced to these elements by burning. He also observed that some substances seemed to break down into more than four elements.

Alchemists saw the four elements as mystical substances whose existence could be reasoned by logic alone. Boyle, on the other hand, believed that elements were concrete substances whose existence could be only verified by experiment. He did not necessarily reject the four elements, and he did not offer a list of replacements for them; however, he wanted chemists to establish the elements based on scientific observations.

Like Libavius, Boyle opposed the mysterious language of the alchemists. He wrote, "And indeed I fear that the chief reason, why chymists have written so obscurely of their three principles, may be, that not having clear and distinct notions of them themselves, they cannot write otherwise than confusedly of what they but confusedly apprehend." He felt that the alchemists' secrecy kept true scientific advances from being made.

Impact

With his book, Boyle helped to transform alchemy into chemistry. He introduced the experimental method into chemistry that was being used in physics. Boyle helped to draw parallels between these two sciences, showing that chemistry was just as worthy of study as physics. This raised the social and intellectual status of chemists above that of second-rate magicians and reduced their tendency for secrecy.

The new science of chemistry attempted to investigate only that part of the universe that is observable. Unlike the alchemists, the new chemists did not attempt to involve religion and philosophy as a central part of their work. Chemists began to focus on chemical substances and their changes rather than the perfection of matter and humanity. Instead of taking ancient beliefs and trying to put them into practice, chemists attempted to form general rules about the natural world based on their own observations.

Prior to Boyle's work, the main method alchemists had used to analyze chemicals was with fire. Boyle believed that fire, although useful, was not a sufficient way to analyze the chemical composition of substances. Therefore, he searched for and described other methods of analysis, many of which are still used today. These included color tests, flame tests, and examination of crystal shape.

Color tests, naturally, involve color changes. One type of color test is the use of acid-base indicators. These chemicals change color when added to a solution based on the solution's acidity. For example, an indicator might turn an acid red and a base blue. This type of test could therefore be used to distinguish acids from bases. Flame tests involve wetting a chemical with hydrochloric acid and then putting a small sample in a flame. The color of the flame often indicates the composition of the chemical. For instance, copper burns with a bright green flame. Although many of these tests had been developed years earlier by other scientists, they became well known because of Boyle's writing. Only gradually, however, did chemists begin to accept other methods of analysis as being equally important as fire.

During the 1600s, scientists began to see language as a tool to express knowledge clearly and exactly, and in The Sceptical Chymist, Boyle helped to clarify chemical classification and naming conventions. The alchemists sometimes had dozens of names for the same chemical. This practice led to great confusion and difficulty of communication. Boyle believed that every chemical should have a single name upon which all scientists would agree. He attempted to connect the names of chemicals with their composition. He had only limited success because the composition of many chemicals was not known at that time. However, the modern naming system used in chemistry is based on composition.

Although Boyle had rejected the four elements of the alchemists, he did not offer an alternative system. Chemists, however, still needed the concept of an element and as a result, they returned to the four elements for lack of an alternative. However, Boyle's work made it possible for chemists in the 1700s to slowly increase the number of accepted elements. An element was eventually defined as any substance that could not be broken down into simpler substances by ordinary chemical means. By 1789, in his Traité Élementaire de Chimie (Elements of Chemistry), the French chemist Antoine Lavoisier (1743-1794) was able to complete a fairly accurate list of the more common elements.

Gradually, the new science of chemistry began making its way into universities. Guerner Rolfinck (1599-1673) began the first university chemistry laboratory in Germany in 1641 at the University of Jena. Throughout most of the 1600s, however, chemistry was not officially recognized at most colleges, except for those in Germany. However, by 1672 Nicolas Lemery (1645-1715) was giving public chemistry lectures in Paris that drew enormous crowds. Chemistry departments began appearing in major European universities in Montpellier (France) in 1673, Oxford (England) in 1683, Utrecht (The Netherlands) in 1694, Leyden (The Netherlands) in 1702, and Cambridge (England) in 1703. Most chemistry programs were initially associated with medical schools, and many of the chemicals produced from university laboratories were tested as medicines.

A scientific revolution had taken place in the 1600s. Astronomers and physicists, such as Galileo (1564-1642) and Isaac Newton (1642-1727), rebelled against the ancient ideas of Greek scientists that had been accepted for centuries. However, a similar revolution did not really take place in the field of chemistry until the next century. During the 1700s, many chemists abandoned the mysticism of the alchemists and began to rely on precise measurements in the laboratory. Eventually, chemical theories based on speculation were replaced by theories based on experiment, and by the mid-eighteenth century, nearly all chemists and physicists had rejected alchemy and transmutation. The spark for the revolution, however, had been set by Boyle during the 1660s.

STACEY R. MURRAY

THE GOLDEN TOUCH

Although the central beliefs of alchemy were discredited centuries ago, people have never lost their fascination with the idea of creating gold from other substances. In fact, with the introduction of modern nuclear chemistry in the twentieth century, it seemed that such a goal might be possible. When atoms of an element are bombarded by high-speed particles, the atoms will sometimes break apart into a lighter atom and one or more particles or into two lighter atoms. As a result, the original atoms are transmuted from one element to another. In 1980, scientists at the University of California at Berkeley fired charged atoms of carbon and neon at the metal bismuth. This experiment transmuted part of the bismuth into gold. However, the sample of gold the scientists produced was so small that it was worth only one-billionth of one cent, or $0.00000000001. The experiment itself cost about $10,000. So, it appears that although it may be possible to change base metals into gold, transmutation is probably not the most practical way to make a fortune.

STACEY R. MURRAY

Science and Its Times: Understanding the Social Significance of Scientific Discovery