Electrical Circuit Controller
611719 10/4/1898
Calls for a "liquified inert gas" as part of an Electrical Circuit Controller.
 
In the specification sheet it says the gas has to be under intense pressure. There's an implication it's easier to keep up high pressure than a vacuum. 

It would seem that some sort of cryogenic arrangement would be the only way to do this, which implies that this patent opens up the whole field of cryogenics.