Vacuum sublimation would be a viable idea for purifying various alkaloids, especially perhaps to rid freebase harmalas from salt residue.
Quote:[does not gasoline vaporize under pressure in the cylinder of a car engine?]
The gasoline is vaporized in a carburettor (or at least, used to be - I'm not sure about modern, computer controlled engines) before it is introduced to the cylinder.
As Sakka says, increased pressure doesn't help anything to vaporize.
Quote:how would it be different than using a normal open pipe... ?
If you mean increased pressure, then IMO it would be cumbersome, potentially dangerous and highly inefficient.
Using reduced pressure as part of a method of administration probably would be cumbersome, potentially dangerous and highly inefficient as well, but for different reasons.
“There is a way of manipulating matter and energy so as to produce what modern scientists call 'a field of force'. The field acts on the observer and puts him in a privileged position vis-à-vis the universe. From this position he has access to the realities which are ordinarily hidden from us by time and space, matter and energy. This is what we call the Great Work."
― Jacques Bergier, quoting Fulcanelli