Which, as you're probably aware, Karlos me ode, is why street lights glow a bit purply before they come on properly - potassium is used to kick off the sodium excitation in these low pressure sodium lights, as its easier to excite.
ahhh flame tests ! takes me right back ... too far back!
Sodium flame tests would be the last one we'd try - it tended to leave the flame discoloured even after the sample was removed.
