I feel though a proper mercury thermometer could be modified to display some very accurate readings though, particularly if conductive glass element is used, if its compatible.
Yes I am just curious if this is an old invention, I don't plan on making it.. if I did, I would use gallium or woods metal, which I have, and maybe with teflon or something (not sure what works). But I am not really interested in how this would be made, just if it was ever made.
It makes me think of like van helsing or something lol, all those secret weapon confederate laboratories must have had this and it has been lost in time to union artillery?
Would a reamed and lapped hole in a teflon cylinder work with galium? You could make it using pencil lead, you can make OK contacts for carbon (like the ones from batteries) by melting it in a mold of molten solder ( like a copper pipe end cap), sticking in the carbon and letting it solidify.