Kontextmaschine

17th August 2022

Post reblogged from Queen Story's Mere Servant with 353 notes

vacuouslyfalse:
Food for man may also be considered as a compound of the original elements, of the qualities, combinations, and control of which, chemistry is daily adding to our knowledge; nor is it yet for man to say to what this knowledge may lead, or where it may end.
it’s really funny to me that this half-assed response to Malthus, who believed that the inability to grow more food created what was basically an inescapable population limit, turned out to be totally correct.
“well, uh, maybe if we study chemistry a bunch we’ll magically figure out a way to grow, like, 100 times as much food as we currently can”
and then we did!
i read something about the early history of understanding of photosynthesis, and in the decades leading up to 1816 when the quote from OP was written, they pretty much figured it out:
Respiration and combustion:
oragnic matter + oxygen → carbon dioxide + water + energy
Photosynthesis:
carbon dioxide + water + light → organic matter + oxygen
Not with this terminology. Some of the people involved worked with the phlogiston theory, phlogiston being pretty much negative oxygen, so they called oxygen “pure air” or “dephlogistonated air”. Lavoisier called it “oxygen” though. And the name “carbon dioxide” doesn’t make any sense pre-Dalton, they called it “fixed air” or “carbonic acid gas”. And nobody was talking about “energy” in this context yet. And the term “photosynthesis” really refers to synthesis of glucose, and they didn’t know that’s what was happening yet.
But in their own terms they knew the reactions described above were happening. They knew the “photosynthesis” part was happening at the leaves in light, and that respiration dominated in the dark.
And the plant nutrients were recently discovered, beyond a vague “they need something from the soil.” This guy de Saussure was doing basically hydroponics in his laboratory.
Jane F. Hill:
De Sassure did not trace the source of plant nitrogen convincingly, but he correctly concluded that the source of this nutrient is not atmospheric nitrogen gas, as Ingen-Hous (1796) and many others had believed.
That’s important because it seems like it may have led to the first big payoff from chemical knowledge, for agriculture. I’m not thinking of industrial nitrogen fixation here, I’m thinking earlier, the nitrate mining in the Atacama Desert in Chile. Of course people have long fertilized soil with manure and other organic fertilizer, but when and how did they realize that the “Chile saltpeter” could be used for fertilizer? How sophisticated or difficult was the process to get nitrates from ore?
Apparently they started mining it in 1810 (according to this source, though idk whether for fertilizer?). And exporting to Europe for fertilizer in the 1830s. So… like… how did they know how to do this and that it would help plants grow? I suspect the knowledge was pretty recent.
Anyway… a lot that I don’t know here… but… I was reading to try and get a sense of what was going on in 1813. It was too early to directly observe chemistry making an impact on agriculture. But if you were attentive to intellectual stuff you could see the progress being made.
I wonder when obtaining nitrogen for fertilizer from the air, using industrial chemistry, was first imagined. Seems de Sassure could have at least thought of it, even though it would be another 100 years before it was executed.
But like… ok, of course people have long known that crop yields are limited by the fertility of the soil, and you’ve got to do all you can fertilizing it just to keep up with the depletion of the soil by crops. And around the time the quote in OP was written, was pretty much the same time they were actually figuring out what materials conferred “fertility”, and shortly before they started getting nitrogen from an inorganic source, the nitrate ores in Chile. The timing makes sense to me. The reasoning in the quote is half-assed but a much more detailed case could have been made at the same time, and I wonder if the author was drawing on another source that fleshed it out more.

Tagged: history