Now, Bond's not a scientist (unless you count excessive drinking and spreading venereal disease as a "science"), so it's no surprise that he can't figure out the chemical properties of a solution by simply picking it up and staring. So instead of, say, taking a couple of vials back to Q for analysis, 007 opens one of the vials and leaves it standing in a precarious position before dashing secretively out of the room.
"This is going to be hilarious!"
Not surprisingly, when the scientists come back, they knock over the vial ...
... which turns out to contain some kind of toxic gas that kills them both while Bond observes from a secure position, not unlike a child hiding behind the couch from a scary movie.
"Huh. So it was poison."
It's pretty fucked up that instead of doing some basic detective work, Bond uses the scientists as guinea pigs. Sure, they might be bad guys, but they also might not be. They're just a couple of scientists, and they're working for the Bond-verse equivalent of Richard Branson. For all we know, they may think they're producing weapons to help fight terrorism, or a better first-class commercial flying experience. Regardless, Bond never bothered to find out before locking them both in a death trap.
"Science that, nerds."