( phase diagram )
It turns out that ice IX does actually exist, as do ice I through XII, though thankfully it does not have the properties described by Vonnegut. Bree tells me that Kurt's brother Bernard was an atmospheric chemist who studied, among other things, cloud seeding—maybe that's where Kurt got the idea. [Above figure from the textbook Thermodynamics and an introduction to thermostatistics, second edition, by Herbert Callen.]