A Three-Layer Liquid

One takes a tall glass capable of holding about half an ounce or a bit more of the various liquids to be employed, and fills a quarter of it with pure iron fillings, or with mercury. Onto this one pours an equal amount of a completely saturated salt-of-tartar solution, onto this an equivalent portion of alcohol, and the remainder one fills with mineral oil or turpentine oil. These liquids remain in place, one above the other, in the order specified, because they are of different weights. Even if one shakes them together they return to their previous arrangement as soon as calm is restored in the vessel.  

This experiment was often used by apothecaries to obtain particularly mysterious fillings for show bottles. Such recipes are the original form of the cocktail, which was invented at the end of the 18th century and takes its name from the bright colors of the liquids, which resemble the tail feathers of a cock. Here is a modern cocktail recipe  

Ice cubes, 1 teaspoon raspberry syrup, 1 dessertspoon maraschino, 1 dessertspoon curaqao, 4 cl brandy, half a peach, 4 cocktail cherries, 1 pineapple cube, mineral water. 

The glass is filled half full with the crushed ice cubes. Raspberry syrup, maraschino, curaqao and brandy are added, the mixture is stirred briefly and topped up with mineral water. 

Naturally the chemist must show what he can do, and the following three-layer liquid is the result. 

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