Isotopes, microscopy, and validating the mechanism

17:54really cool technique that I thought they used was something called stable mass stable isotope mask spectroscopy. Okay. Here's the idea. So, you know, in nature you've got isotopes. Isotopes are elements that have different numbers of neutrons versus protons. And so they're going to be heavier. Like for example, oxygen um 18 versus oxygen 16. Same chemical properties, but it's just heavier. >> Okay? >> Which means if something gets hot, right, the the heavier oxygen is going to move slower. And so in any reaction, there's going to be more lighter oxygen

18:35that's gonna do the reaction versus the heavier stuff, right? >> Because it's moving faster. The lighter oxygen is moving faster. So you can actually calculate you you can you can do an experiment and you can figure out from mass spectroscopy how much of each isotope is in the substance that you're looking at. >> Got it? >> Does that make sense? >> It does. It does. >> Right. And so that's what they did. What they looked at was how much of carbon 13 there is and how much oxygen 18 there is. And what they found was that the the the slope of of these lines if you look at photo 16 right >> it's characteristic of that water limited high temperature fractionation.

19:16>> Oh I see what you're saying here. >> So so the the gray triangles >> are what they found >> at the site in Pompei. And what you're looking at the the red box is where most of that those gray triangles are. And that's exactly what would happen if you premixed. >> And then you and then you put water. >> That's that quick lime. >> Yeah. That's that quick lime. Exactly. And so the slake lime samples, that's the cold mixing. That's the stuff that you want to use for finishing because it's smooth and you can plaster it onto the wall and then you can, you know, put mosaics and like paintings and the ornate stuff. But if you want the structure, you want you want the concrete that actually self-heals, you

19:56actually want to do it with the hot stuff. >> This is so like and so it's interesting like there there was also this understanding of the dual use at these different at these different >> That's what's insane. That that's really cool. And and here's here's actually like what's what's sort of happening with the the quick lime. Okay. And I I haven't gotten into how how exactly it would work, right? like how how would why would these chunks of lime peel concrete? >> Mhm. >> Right. Here's what's happening. So suppose you've got concrete and you've got a crack. >> Okay. >> Now you've got a crack in the concrete.