We know salt elevates our cooking, an easy way to sharpen and brighten other flavors. But what about our cocktails? We'd noticed some trendy mixologists using droppers to add minute amounts of saline—a tincture of salt and water—to our drinks. Was this a hipster bar flourish or did it really make a difference?

Anyone who has crunched through the salt rim of a margarita knows salt changes a cocktail, but that's culinary equivalent of dumping the entire shaker on a steak. We wanted to know whether a more nuanced approach mattered.

To find out, we started by learning a bit about how salt enhances flavors. Because salt is one of the basic tastes, this simple mineral can have an outsized impact on how we perceive other flavors, most notably heightening sweet and masking bitter.

So we created saline solutions—kosher salt and tap water—of varying concentrations, from 1 percent up to 10 percent by weight. We then tested several drops of each in a series of old fashioneds, a drink that relies on cocktail bitters to marry a bit of sugar and peppery bourbon.

The 6, 8 and 10 percent solutions were too strong, giving the cocktail a mild salt water flavor. Solutions of 1 and 2 percent were undetectable. But ½ teaspoon of 4 percent saline had a profound and pleasant effect, rounding out the cocktail's sweet notes, heightening the vanilla in the bourbon and mellowing the bitters.

We then tested the 4 percent solution in a variety of cocktails—the negroni, Moscow mule, daiquiri, and a vodka martini. In each case, the cocktails with a few drops of saline tasted more complete and smoother.

Making the saline was simple. Mix 4 grams (a generous ½ tablespoon) Diamond Crystal kosher salt and 96 grams (6 tablespoons plus 1 teaspoon) water until the salt dissolves. The saline can be stored indefinitely at room temperature.

In every cocktail but the martini we used ½ teaspoon of the saline. The simplicity of the martini—fewer flavors to balance—called for slightly less, about ⅛ to ¼ teaspoon.