Hmm? Limestone is high in calcium. Calcium, when mixed with stomach acids, would form hydrogen. Hydrogen is lighter than air, thus giving the lift you talk about. Something like a blimp.
16 seconds sound clip from the The Flight of Dragons movie soundboard.
You can hear this line at 00:42:55.578 in the Blu-ray version of the movie.
Quote context
[...]
- They help grind up the white fire rock when you eat it.
- A puny man word if I ever heard it. Eat!
- It's like birds use grit to grind seeds.
- Yeah, but don't talk with your mouth full.
- What's all this to do with flying?
- It makes the fire in your belly that gives you lift.
- What? You got fire inside you when you go up. That's all you need to know.
- No, that's not logical. How could my ribs contain fire?
- Aw, for crying out loud. Visualize!
- Now, as you explain, I'll make a diagram.
[...]