Print

Please login or register.
1 Hour 1 Day 1 Week 1 Month Forever
Login with username, password and session length

[Shurhaian]

Technically, diamonds suffer a very, very slow decay(into graphite, not gas). I'm not entirely sure that applies at room temperature, but from what I remember of reaction kinetics, specifically that there WILL be some high-energy outliers in the distribution curve at any temperature, it seems likely. But modelling that would be a nightmare and a half.

Even for substances that do so more rapidly it might be more trouble than it's worth.

Also: We do so have air tight spaces. Otherwise you wouldn't be able to seal that reservoir with doors/floodgates.

And pressure differentials do NOT so quickly normalize. Exhibit A: Tornadoes. They have a gigantic pressure differential, and it persists. If the pressure equalized at speed of sound, that would mean that, to maintain the differential, the winds that set it up would be moving at mach. This is not the case.

Air pressure normalizes as quickly as the air moves around. For an ideal gas, this would be the speed of sound. Air is not an ideal gas. Particles bump into each other and eddy and otherwise don't always take the most direct route. On the microscale it works, but even the scale of a fortress is not so simple. Pressure distances are settled by drafts, not sonic booms.

[SolarShado]

correct me if i'm wrong, but: water-tight =/= air-tight

[Shurhaian]

For all intents and purposes it's the same thing. Certainly if the vessel is going to take pressure, water would squeeze out through any tiny crack. The main difference between liquid and gaseous fluid-tight is that liquids won't flow up on their own, and gases are more prone to doing so. As soon as you introduce pressure, though, that no longer helps you.

In some ways, sealing water could be MORE difficult because it doesn't compress as gases do. To a point, you can shove more gas into a vessel; for water, you have to build it big enough to hold all the water, period.

Even if there is a slight difference, such a close seal would certainly be enough to interfere with and slow the air movements that equalize pressure, and that's the reason it came up.

[lucusLoC]

it is way easier to seal a liquid than a gas. surface tension in most liquids means that they generally seal any small gaps by themselves, even when under moderate pressure. it is almost impossible to get mercury to pass through even visible cracks because of its extremely high surface tension.

gases do not have this benefit, and so leak out of any small gaps when there is even a slight difference in pressure. in general "air tight" means no small holes at all, 100% sealed (and thus water tight as well), whereas water tight means that it may have hairline cracks or pinholes, but it will contain water or similar liquid without leaking at all under its specified operating parameters.

of course all this depends on the context of the conversation, and you can of course find exceptions to these rules.  for example there is a class of gasses that are "sticky" and so display something kind of like surface tension. they are large organic molecules if i remember correctly. and there are also liquids that display next to no surface tension, and so leak easily from even the tiniest cracks. alcohol is an example of this, again, if i remember correctly. you even have gasses that can leak slowly through solid steel, like hydrogen.

[Shurhaian]

The point, since that seems to have been missed:

It is not only possible, but fairly commonplace, for fortresses to have areas at least tightly-enough sealed that pressure wouldn't equalize quickly across the boundary. Thus, a simplistic model of air pressure is liable to generate as much inaccuracy as it is to add detail, if not more.

[Great Cthulhu]

Also, there's no way air pressure could be modded in, so this really isn't the correct forum for this discussion. If anyone wants to continue the debate, please consider going to suggestions.

Just tryin' to get the discussion back to Molten Rocks.

[Athisus]

The metal cobalt has a melting point of 2723 F. Has anyone considered moding in cobalt for this sort of thing? In related news, cobalt has a boiling point of 5301 F.

[SirHoneyBadger]

Tungsten has an extremely high melting-point. The highest of all non alloys (3,422 °C, 6,192 °F).

Cobalt would be nice to see in the game, but even iron has a higher melting point.

The six metals with the next highest melting points after tungsten are as follows:
Iridium 2,443 °C (2,716 K)
Niobium 2,468 °C (2,741 K)
Molybdenum 2,617 °C (2,890 K)
Tantalum 2,996 °C (3,269 K)
Osmium 3,027 °C (3,300 K)
Rhenium 3,180 °C (3,450 K)

All are very interesting in their own ways, and all of them would be nice to see in the game.

[Grax]

Tungsten has an extremely high melting-point. The highest of all non alloys (3,422 °C, 6,192 °F).

Cobalt would be nice to see in the game, but even iron has a higher melting point.

The six metals with the next highest melting points after tungsten are as follows:
Iridium 2,443 °C (2,716 K)
Niobium 2,468 °C (2,741 K)
Molybdenum 2,617 °C (2,890 K)
Tantalum 2,996 °C (3,269 K)
Osmium 3,027 °C (3,300 K)
Rhenium 3,180 °C (3,450 K)

All are very interesting in their own ways, and all of them would be nice to see in the game.

How will dwarves melt it?
Even refined coal doesn't give the neccessary temperature and electric or powder metallurgy are absent in those times.

[SirHoneyBadger]

Melting them might do with some magical assistance, in this case.

Wouldn't have to, necessarily, but the realistic options might be more beyond the scope of the game than a magical solution.

Maybe there will simply be some artifacts and other items in the game that just happen to be made of these substances? sans much explanation.

[Grax]

The only case dwarves could melt such an infusible materials without magic is the alternate reality with solar smeltery of "archimedean type" consisting of an array of silver, bronze or obsidian mirrors (or maybe of quicksilver alloy as it [alloy] is in my mod).

Idea is in [quantity/quality of mirrors] equal [for resulting temperature] with a some quefficient of biome.
Desert is the best, swamps and rainforests is the least.

[Igfig]

I found a thing with some interesting numbers in it: FREED.  It's a database of a whole bunch of minerals and their relevant data.

The formatting is bad, the documentation is atrocious, and I don't know anything about thermochemistry, but here's some data I got from the demo version (the full version is about three times larger but costs $10):

Cinnabar (HgS) boiling point: 618 K
Limestone/Marble/Chalk (CaCO3) boiling point: 1757 K
Magnetite (Fe3O4) boiling point: 1811 K

I'm sure there's a lot more useful data in there, but it's not easy to find.  It gives a bunch of numbers that can be used to calculate specific heats, but not the specific heats themselves.  If you can figure out how to use FREED, you'll probably get a lot of great data.

[Quietust]

Interesting that this thread got resurrected, since it makes it a bit more convenient to make a significant correction:

Magma's temperature in-game is exactly 12568 in dwarven units, as confirmed by the wiki and some independent testing I have done.

That is entirely wrong - in version 0.28.181.40d, magma's temperature is exactly 12000 in Dwarven units, as indicated by dtil and further confirmed by adjusting the melting point of an item submerged in magma (in my case, iron metal, in a fortress whose magma moat was littered with goblin armor); with a melting point of 12000, items long submerged in magma instantly melted, and upon raising the melting point to 12001, it all instantly solidified.

[sunshaker]

Maybe we should begin collecting the chemical formulas for the stones and minerals and maybe any uses for them (cinnabar refining to mercury which is used to refine gold, flint and chert being used as stone tools (ie they should be [SHARP] though if it was possible perhaps not as sharp as Obsidian), that sort of thing).