19 Floréal II

"Rien ne se perd, rien ne se crée, tout se transforme."

This is the way the French state the Law of the Conservation of Matter which they tend to call, with some chauvinistic justification, le Loi de Lavoisier.  Tout se transforme also sums up the state of French politics in the final years of Lavoisier's life.

Lavoisier hears doorbell

Antoine-Laurent de Lavoisier was a Parisian aristocrat (it's all in the "de") who inherited a mort o' money when his mother died. He was also sharp as a tack, observant, careful and questioning. Instead of spending his money on the dhrink or debauchery, he devoted his life to science, not least science in the support of the state.  He lived for nearly two decades in a grace-and-favour house in the Royal Arsenal and greatly improved the quality of French gunpowder by sourcing better ingredients and standardising the production process. Notably, he converted part of the house to a scientific laboratory where he investigated a range of chemical and biological conundrums. That's when he wasn't out in the field helping to carry out the geological survey of France in Alsace-Lorraine.

Where to start?  You couldn't cover all his contributions to science in a trifling 1000 words on a blog. But he remains in the history books because of his discovery of the element oxygen - indeed the name oxygène he gave to this most active part of 'air' - the acid generator - is what has stuck for most of us in science, Although some languages prefer a German rather than a Greek root - zuurstof in Nederland or Sauerstoff across their Eastern border. The story of the discovery is a corner-stone of Thomas Kuhn's iconic 1962 investigation of the history and process of science "The Structure of Scientific Revolutions".  At the same time as Lavoisier was tricking about in the Royal Arsenal, the great English chemist Priestley was carrying out a similar series of experiments showing, for example, that the respiration common to all living things is chemically the same as burning logs in a fire: "la respiration est donc une combustion," as Lavoisier put it.  Priestley and Lavoisier agreed on that; but their understanding of what was happening at a molecular level was diametrically opposite.  Priestley held to a theory that combustion involved the release of a substance called phlogiston - which was obvious to all thinking people - you just have to see flames issuing from a log to appreciate this.  Lavoisier started out by agreeing with this theory but gradually made a volte-face and twigged that combustion was actually the addition of something (oxygen) to the burning material.  This not so o.t.a.t.p because you can't sit on your sofa and watch - you have to get off your arse and start measuring things (temperature, weight), really carefully, and recording the results and meticulously keeping records and repeating and repeating your experiments.  Science is Hard.  Insofar as people know anything at all about the History of Science, they tend to get snitty about Priestley and his pathetic adherence to an outmoded doctrine. It is easy enough to be smug if you have 20/20 hindsight but in the context of the time and what was known back in 1780, phlogiston explained a lot and in an internally consistent way. Here is a sensible and insightful look at the controversy and its resolution.

It must have been exciting times scientifically.  But it was also an interesting time politically, with the revolution in France shaking to the core people's certainties about what was possible socially and religiously.  Lavoisier shed his "de" and high-falutin' hyphenated first name, left his house in the Royal Arsenal and tried to look like Citoyen Lavoisier but his embedded association with the Ancien Régime was too much for people who were dwarfed by his intellectual achievements. When he was brought before a revolutionary tribunal, the judge dismissed an appeal that Le Grand Fromage should be let alone to continue pushing the frontiers of science with his experiments: "La République n'a pas besoin de savants ni de chimistes".  A few years earlier Voltaire had responded to the execution of English Admiral Byng on his quarter-deck with the quip "il est bon de tuer de temps en temps un amiral pour encourager les autres".  History is only as useful as its reflection of what we see in today's mirror. Hands up anyone who can name a republic that would happily incarcerate if not actually execute a scientist today because s/he was dissing the dominant religion.

Antoine Lavoisier was tried, condemned and executed all in the day called Arroche 19 Floréal II, exactly 220 years ago. Every day of the year had been given a name by the logical obsessives of the French revolution:  plants, tools, animals and minerals were all commemorated in a vain effort to supplant the idea that every saint had his/her day. 19 Floréal was dedicated to Arroche  Atriplex hortensis which we call saltbush or Orache.  Saltbush or mountain spinach is eminently edible and you are exhorted to go and find some: it's much more interesting than reg'lar spinach and a fit dish to remember a man who was much more interesting than reg'lar scientists.

As the contemporary brilliant mathematician and astronomer Lagrange put it: "Il ne leur a fallu qu’un moment pour faire tomber cette tête, et cent années peut-être ne suffiront pas pour en reproduire une semblable."  In other words: decapitation is forever, which is as good an argument against the death penalty as you're likely to find.  What a waste.