
Celery salt is table salt blended with ground celery or lovage seed. The salt is most of it; the seed does the flavoring.
Plain salt with a pinch of ground celery seed rebuilds it exactly. Plain salt alone gives the salinity and none of the celery, which matters little on a rim and a great deal stirred in.
Celery seed
The pure spice, no salt, and one-for-one it leaves the drink unsalted and the celery far louder than intended.
Celery bitters
An alcoholic tincture dosed by the dash, aromatic instead of saline; it seasons the drink itself; celery salt seasons the rim.
The salt keeps indefinitely; the celery seed fades. Sealed and dry it holds its aroma a year or two. Moisture turns the whole thing into a solid cake that is perfectly good and no longer pourable.