"You think you could learn to fetch air? I didn't know that was possible. Although I guess I don't see why not, it's possible to Fetch water it just makes a mess." 

"I'm pretty sure it's possible in principle, but I may or may not be able to learn how. Hmm, can you think of anything else to do with this box before unsealing it?"

"We could wait for it to cool down more? Although I could also put a barrier around it, so we don't risk getting burned." 

"I think putting up a barrier will help more than waiting. It's hard to tell how hot it is just by looking, and I'm worried being sealed will make it take a long time to cool--sort of the opposite of how a breeze cools you down on a hot day."

"That's a good point. Hmm, can you do a barrier, you're stronger than me." 

"Sure." Nice strong barrier shield around the tank.

Sandra carefully melts the box so she can crack open the top, and– 

- hisssssss - 

It makes a teakettle sort of noise as a lot of warm air gushes out. 

"Wow, that sounded like there was more air in there. I wonder if that's because of the fire or if hot air always does that."

"We can test that! If we clean this out and I seal it up again, I bet you can heat it up in there without there being any fire." 

"Yes, definitely. Or cool it down, now that I think about it."

"Let's try it! Hmm, can you help me get all the stupid ash bits out of this thing with Fetching, so I don't have to open it all the way..." 

"Sure." Fetch Fetch Fetch this is much better than getting soot on his hands.

Once it's cleaned out, Sandra seals it up again. "All right, hot or cold first?" 

"Hmm, how about hot first? Seems more likely to have an interesting result. Here goes . . ." he makes a tiny little weather-barrier to push heat into the box, thinking that they should come up with a precise way to measure temperature.

"- Um, maybe stop?" Sandra says suddenly, pointing to a corner of the box, which is still a bit soft from her re-sealing it plus the extra heat inside and is now bulging outward. 

He stops immediately and puts up another barrier, right up against the glass so it can shore up the weak spot in addition to protecting them.

"Hmm," Sandra says, watching as the barrier doesn't burst, and in fact slowly subsides. 

"Want to try opening it now?" He rearranges the shielding so there's space for air to rush out if it's going to.

It does rush out! Possibly with even more enthusiasm than before. 

"Looks like it's not just the fire! Hot air wants to take up more space."

"I wonder if the reverse is true with cold air! Hmm, it's let out everything it's going to - I'll seal it back up while it's still warm inside and then you can do that backward and cool it, maybe?" 

"I can do that. It's less likely to try to explode, even. I guess it might try to collapse?" He reverses the weather-barrier and starts sucking the heat out.

Sandra watches closely. The box doesn't collapse, though she does warn him that glass might be more brittle when it's very cold. 

After a while water condenses on the inside of the glass, then turns to frost. "Alright, it looks pretty cold in there now." 

When Sandra tries to peel it open, it instead cracks and splinters along one side. 

"Whoops, I guess it was brittle." 

The air whooshes again, with less vigour, but clearly in rather than out.