The changing nature of theories over time
The Time When Science Didn’t Know How Fire Worked
2023, Jacquline Dacres ©
I saw someone burning a pile of paper yesterday. As I watched the flames dance, I remembered the phlogiston theory. Don’t worry, I can’t pronounce phlogiston either.
So, have you ever burnt or noticed a log burn completely? It burns until it becomes ash. Interestingly, the original log and the remaining ash clearly don’t have the same weight. The ash weighs far less than the original log that was burnt!
In science terms, you made an observation. You observed that what remains after burning weighs significantly less than what was originally burnt. We make observations every day when we notice the little details of our lives. It’s mostly unconscious so we often don’t realize that we’re doing it.
Anyway, back in the 1660s a German alchemist — Johann Joachim Becher — noticed the very same thing. He saw that the weight of the ash was less than the original weight of the log it resulted from, and he came up with a theory to explain what he saw.
Becher believed that a substance known as terra pinguis was a key feature of combustion and was released when combustible substances were burned.
One of his students, Georg Ernst Stahl, thought so too. So much so, that he further developed and expanded on the theory. Stahl renamed terra pinguis to phlogiston.
According to Stahl, the log contained a substance called phlogiston. In his theory, phlogiston was the weighty material inside of all substances that was lost when a log — or anything else for that matter — burned. The loss of phlogiston explained why the remaining material after burning was vastly lighter.
I don’t know about you, but this seemed like a fantastic explanation to me.
Many years later a French chemist called Antoine Lavoisier, came along. Some people never know when to leave things alone, and Mr. Lavoisier was certainly one of them. He conducted a lot of experiments in which he burned a few metals as well as sulfur in a controlled environment.
Lo and behold, the weight after burning these chemicals was greater than the weight before burning. Of course, he couldn’t keep this result to himself. He told everyone. As expected, this caused an upheaval in the scientific community.
These two observations were incompatible with each other. In one case weight decreased after burning and in the other case, weight increased. Absolute confusion reigned — no wonder people stay away from studying science.
Mr. Lavoisier concluded that when an object was burned it combined with oxygen in the air. This combination is what leads to an increase in weight.
But that went against the predictions expected from the phlogiston theory.
Mr. Lavoisier’s theory eventually became the accepted explanation. What was amazing is that supporters of the phlogiston theory refused to let go of it even when faced with evidence that contradicted their belief.
Instead, they tried to modify the theory to make it work with what Lavoisier was doing in his experiments. In doing so, phlogiston theory became more complicated.
The phlogiston theory eventually lost popularity and was swept to the wayside.
Lesson: Every day we make observations. We receive input from all over into our brains. Whether we realize it or not, we often try to formulate an explanation for what we observe.
However, our explanations or interpretations of an event are not always accurate. Sometimes our interpretation is based on how we feel and what we have been told rather than on facts.
Bear in mind that what’s a valid explanation today may not be valid 50 years from now as knowledge increases and more information becomes available.
Similarly, sometimes with maturity, our beliefs and explanations may also change. That’s okay. Always leave room in your mind for the chance that what you believe may not be accurate. Leave room for being wrong.
“If you change the way you look at things, the things you look at change.”- Wayne Dyer
Okay, I won’t leave you hanging. I know you’re wondering — why does a log lose weight when burnt? Here’s the (relatively) simple answer:
Because it wanted a ‘lighter’ version of itself.
Seriously speaking, a log loses weight when burnt because the chemicals inside of it break down and recombine to form carbon dioxide and water vapor. Both carbon dioxide and water vapor are released as gases into the atmosphere.
This release of gases, along with the relatively small amount of solid ash residue, contributes to the apparent loss of mass during combustion.
See, science isn’t so bad after all, right? 😃
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