Seals For The Goetic Presidents? Options

Sorry if this has been asked before, but I didn't see it.

Various copies of the Goetia refer to Mercury as the metal of the Presidents, which is all well and good, until you get to the point with the Spirit when for whatever reason you are supposed to, or want to inscribe its Seal upon the appropriate metal. Copper, Tin, Silver, no problem. But how am I supposed to inscribe on Mercury?

I've been considering brass, as it is also attributed to Mercury, or an alloy with Mercury, but I was wondering if anyone else has another idea/suggestion.

The method you described opens up a lot of possibilities just for the Greater Key alone. I'm not so sure about the Lesser Key as a lot of the spirit/planet 'rulerships' seem to be arbitrary at best, like the spirits were being forced in to a model that wasn't necessarily correct, just efficient for the time it was compiled. But the alchemical method you describe seems like it would be useful for just about any form of planetary magic. Hmm...

*goes off to ponder*

This post has been edited by Darkmage: Nov 25 2007, 08:54 PM