Pour each liqueur in the order they are listed, beginning with the grenadine, carefully down the inside of a Pousse café glass over the back of a teaspoon positioned down at an angle against the inside of the glass so that each layer floats on top of the previous layer.
There is a section in Jerry Thomas's 1862 edition of How to Mix Drinks called "Fancy Drinks" that begins with three Pousse Café recipes. The first is from an early-nineteenth-century saloon owner from New Orleans named Joseph Santina, whom Thomas credits with improving the whole category of cocktail with his Crustas. Santina's Pousse Café is made with Cognac, maraschino, and curaçao. Thomas's instructions say to "mix well" — not what I expected to find in what I have always assumed was a layered drink. Although Santina's may not be layered, mine is. (For a variation, see ABC Pousse Café). This grouping will really test your skill and the steadiness of your hand.