There is a very old Belgian family whose head is the Vicomte Vilain XIV, the Roman numeral signifying not his place in the descent but the power of superstition.

In the Middle Ages, a local ruler, about to sit down to dinner at his hunting lodge, discovered that the number who were to dine was 13. Bad luck, so he summoned a peasant, or "vilain," to join them. But kings do not eat with peasants, so he immediately made the fellow a nobleman, providing a 14th guest and creating the family that was to go down in history as Vilain XIV.

The peasant would agree that good luck comes to those who avoid 13.

But with Friday the 13th approaching, are people still as superstitious as they were? The White House says it is only coincidence that no social event is scheduled for that evening. And there hasn't been a sudden gap in the calendar at Ridgewell's catering.

Yet there are so many superstitions connected with dining that Larousse Gastronomique has a whole entry on the subject. It would be fun to see how seriously people still take the old beliefs. There could be no better date than Friday, Aug. 13, to give a white magic/black magic dinner party, where you test the lingering strength of superstitions. Among the ways:

* Provide small salt cellars at every place at the table and suggest that each guest spill a few particles. Eating below the salt is bad, but spilling it is worse since salt signifies friendship. (Salt was never present on a witch's table.) To spill it indicates disagreement, which, of course, can be fended off if the spiller immediately picks up a pinch and throws it over the left shoulder. See how many of your guests can resist.

* When inviting your guests, warn them that those who enter a house with their left foot first bring evil to the inhabitants. See who does.

* Set a bowl of marigolds in the center of the table, but warn guests that if they stare at them too long, they will take to drink. Buy extra wine, which you will need anyway, because spilling wine is a lucky gesture.

* As guests stare long and hard at the marigolds, warn any single souls that if they drain the last drop of wine in the bottle, they will marry within a year. If already married, they will have a daughter.

* Rest a ladder across the doorway to the bathroom. See if someone tries to remove it.

* Place a fork and spoon crosswise on one of the plates. Tell your guests that it is a sure sign that the food will poison and kill.

If any female guest is wearing a new dress, she must be pinched for good luck.

Place two spoons in the saucer of one of the coffee cups. The guest who chooses that cup will be married soon.

* If you're serving bread, make sure the guests replace the loaf right-side up. Turn it upside down, and you guarantee misfortune.

* Place small pocket mirrors next to each plate and challenge those who say they're not superstitious to break one.

* Hand an umbrella to any guest who has broken a mirror and see if he or she will open it in the house.

* Even though it's not the holiday season, serve mince pie. You will be guaranteeing every guest who eats it a month of luck.

* As you move into the living room for coffee, notice what each guest has done with the napkin. Anyone who folds it, instead of leaving it crumpled by the plate, will never visit your house again.