There’s something vaguely Celtic or mythic to the sound of this word. The /kl/ and the /θr/, with their voiceless-liquid combinations – one crisp, the other soft – are reminiscent of Tolkien’s elvish tongues. It has such odd old echoes: cloth and clash, threat and thread and maybe threnody, lath and rate. Is it a ruling council? A clan of druids and mages? Perhaps a prison, an ancient cage holding a noxious thing awaiting its release after millennia to issue forth as a destructive vaporous spirit once the bars melt away?
That last one, yeah.
Well, it’s more than that. A clathrate, generally, is a molecular cage: the crystalline lattice of one molecule traps within it another molecule. The word clathrate comes via Latin clathri ‘lattice’ from Greek κλεῖθρα kleithra ‘bars’. There are many molecules that can cage and many that can be caged. But perhaps the best known and most feared clathrate is a cage made of water – the hard expansive lattice of ice, like microscopic geodesic cages, less dense than the liquid – containing as its prisoners, one in each cell, molecules of methane.
Chemists say that the methane is the “guest” of the water clathrate. This is rather like calling General Zod a guest of the Phantom Zone in the Superman movies. The methane is a gas, but when it is caged in the icy clathrate it is frozen in place, like suspended animation or consignment to another dimension. Waiting.
Where do you find such clathrates? Under the seabed and in the permafrost. And if and when these long-frozen beds thaw, the methane is released. It can build up pressure and explode, as happened recently on Russia’s Yamal Peninsula, making a big hole in the earth, as though some ancient beast had broken free. Or it can simply, insidiously, bubble up. And when it is loose, where does it go? Into the atmosphere. Where it can be a potent agent for further warming the planet… to release more of its friends…
But a cage of suspended animation does not always contain an enemy. Han Solo was kept in suspended animation, a masculine Sleeping Beauty. And our own minds are clathrates of memories, thoughts and images and feelings long locked up in the permafrost of passed years. Perhaps it’s just a coincidence that clathrate sounds a bit like classmate and I was at a high school reunion this past weekend, seeing some people for the first time in 30 years. Ah, memories. And we had a gas!