Our next stop is Germany, and the year is 1858. We're here because this is where people are coming one step closer to answering a very old question: what is rubber? It's hard to say what the ancient Mesoamericans had to say about this. Too many of their own written records were destroyed by the Spanish after the Conquistadors had wreaked their havoc. We do know that European scientists, including Joseph Priestley, tried to answer this question, and it stumped them for a long time. But now we're on the verge of a breakthrough. A Scottish scientist named Archibald Scott Couper is about to let the world know about a discovery he has made, but another scientist has just beat him to press. This fellow is a German chemist working at the University of Heidelberg named August Kekulé von Stradonitz. The theories of these two chemists would bring the world a little closer to understanding rubber.
Until now, "What is rubber?" has been a hard question to ask because people really don't know much about what anything is. We know a few things, though. We suspect that everything that you can touch, see or feel is made of molecules, tiny particles too small to be seen. We even suspect that molecules themselves were made of even smaller particles called atoms. There are about 114 different kinds of atoms, though not all of them have been discovered yet in 1858. But we do know that some substances were made of only one kind of atom. We call these substances elements.
Compounds are substances whose molecules are made of more than one kind of atom. But the strange thing is that an awful lot of compounds were made from the same two elements, carbon and hydrogen. How is this possible? The answer is now showing up in an idea called valency, which Couper and Kekulé have developed independently.
Valency is a new idea in the late 1800s, and not everyone has accepted it yet. The concept of valency is not hard to understand. It is based on two principles:
2) An atom of a given element usually joins to the same number of other atoms. For example, carbon likes to bond to four other atoms, oxygen likes to bond to two other atoms, and hydrogen likes to bond only to one other atom.
Though Couper and Kekulé have both pioneered this idea, it would not have be a good idea to put these two in the same room together, thanks to a rivalry that will spring up between them. Both have written papers on the subject of valency this year, 1858. Couper's was first, but Kekulé's was the first to be made public. Kekulé is becoming a star, while Couper is being overlooked. He might not be forgotten, but Couper will be so bitter that he'll never worked as a scientist again. Needless to say, this is going to ruin his chances of making any new discoveries that might make him famous.
So what does this have to do with rubber? In the late 1800s, all those scientists who have been wondering about rubber for so many years, can start to figure out what rubber molecules are like. They know that they were made from carbon and hydrogen atoms, but no one knows how the atoms were arranged in a rubber molecule. Remember that the theories of Couper and Kekulé state that the properties of a material are determined by how its atoms are arranged to form the molecules that make up the material. Knowing more about rubber molecules would help scientists better understand how to use rubber, and maybe someday help people to learn how to make synthetic rubber.
While Couper and Kekulé are telling the world about valency, this is going on in the rest of the world:
1857: In France, Louis Pasteur discovers that fermentation is caused by microorganisms.
1858: In China, the province of Guangdong is invaded and occupied by French and British Armies.
1859: Abolitionist John Brown leads a raid on the U.S. Army arsenal at Harpers Ferry, Virginia, hoping to steal guns for a planned slave uprising. This raid fails, but increases the tensions that lead to the U.S. Civil War.
Archibald Scott Couper and August Kekulé von Stradonitz - biographical sketches, part of Chemical Achievers from the Chemical Heritage Foundation.
Friedrich August Kekulé: A Scientist and Dreamer - an imagined interview from the Woodrow Wilson Leadership Program in Chemistry.