Priestley and the story of dephlogisticated air

The facts, as they stand, are these: every creature, when respiring, releases phlogiston. In fact, respiration is simply to be considered a form of combustion. Anything that can burn contains phlogiston. Substances, when burnt, release this weightless, invisible substance -- an element of their being, their composition -- the phlogiston. The phlogiston is always in need of somewhere to go. Such as, air is best for the phlogiston. Air can absorb it. Taking this mode of thinking to its furthest logical conclusion we can only state that the reason creatures “suffocate” is because there is nowhere for the phlogiston to go. When air was removed from around a living creature then there is nowhere for the phlogiston to go and so respiration would cease and the creature died.

Every now and again we are reminded that science is trial and error, an ongoing process. A collection of our true best current understandings. Yesterday’s taboo and tomorrow’s cliché. And quite often vice versa. We dismiss the science of old for its slavish and almost religious sticking to dogma, classical and entrenched in superstition. Most importantly, we learn the power of negative results.

Alas, this is not a story of when science “gets it wrong” so to speak. This story serves as a parable to negative results. This is the story of the accidental discoverer. Joseph Priestley. The man who stuck by his wrong theory, right to the very end.

A mild-mannered chemist by nature, Joseph Priestley goes down in the history books as discovering oxygen. Except that he didn’t, and yet, at the same time he did. The problem was he didn’t realise what he discovered. This new-found discovery he called "dephlogisticated air".

You see, this was a recurring problem in the scientific life of Joseph Priestley.

“It has often been claimed that Priestley was a skillful experimenter who lacked the capacities to analyze his own experiments and bring them to a theoretical closure.”

In other words, Joseph was a man that lacked the ability to connect the dots. In this day and age he would probably be the inventor of many answers in search of a question (the guy who invented Twitter for example). Or perhaps carbonated water. Soda water, something he named “mephitic julep”. His mephitic julep was developed hoping it would be the cure for scurvy. When that didn’t quite work he gladly handed over the recipe to a Mr Schweppes, securing his place in an alternative history where we all drink Priestley bitter lemon with ice. Other examples of the talented Mr Priestley include him being the first to note the electrical conductivity of graphite, as well as the first to describe the use of India rubber to erase pencil marks.

A common trait to all scientists is their stubbornness. Joseph was no different. The phlogiston theory, for lack of a better metaphor, had a lot of holes in it. When something burns its weight increases, and yet if a substance is to lose phlogiston from its being it should lose weight. A simple paradoxical problem to solve -- the phlogiston had a negative weight. Joseph was indeed inventive to think along these lines.

For much of the 18th century this was the popular school of thought, until the French -- Antoine Lavoisier -- rivals to the English and American way of science, saw a different way to look at things and called it oxygen instead.

Joseph championed the colourless odourless gas he had discovered as phlogiston right until his old age. Even after he had been harrassed out of England and fled to America as a result of his opinions on God and politics in his incongruous political and theological writings. In 1796, 8 years before his death, he published a final scientific paper on why the phlogiston theory was still valid, and why the Antiphlogistic theory had got it wrong.

“And yet, not having seen sufficient reason to change my opinion, and knowing that free discussion must always be favourable to the cause of truth, I wish to make one appeal more to the philosophical world on the subject, though I have nothing materially new to advance. For I cannot help thinking that what I have observed in several of my publications has not been duly attended to, or well understood. I shall therefore endeavour to bring into one view what appears to me of the greatest weight, avoiding all extraneous and unimportant matter; and perhaps it may be the means of bringing out something more decisive in point of fact, or of argument, than has hitherto appeared.”

Ironic when you think that Joseph Priestley came to prominence at a time when many still believed, as Aristotle did, that there was but one “air”.

An undoubtedly brilliant man, imprisoned by the four walls of his conviction.

References:  doi:10.1016/j.endeavour.2010.07.005 ; doi:10.1016/j.resuscitation.2004.04.007; doi:10.1016/S0039-3681(03)00022-0; doi:10.1016/j.jemermed.2004.10.012


Written by Dr. Charles Ebikeme for The All Results Journals.