All this makes attempts to create cocktails using old recipes and new liquors a crapshoot at best. When Nicolas de Soto, the head bartender at the Experimental Cocktail Club, sees bartenders pore over the 1930 “Savoy Cocktail Book” as if it were the Bible, he shakes his head. “The ingredients aren’t the same anymore,” he said. “You can’t use the same recipe.”

The vintage stinger made at the club, however, may come closer to the target. It combines a 1960s-era Hennessy Cognac and a crème de menthe from the 1940s. Both are noticeably less sweet that their contemporary counterparts. The resulting drink is restrained and elegant. As for the Gordon’s gin, the club’s 1950s specimen is rounder and maltier than the product sold today. (Though only vintage cocktails are listed on the menu, individual spirits can be ordered on their own.)

All the same, making cocktails with older ingredients doesn’t necessarily mean getting exactly what your forebears drank. There’s the matter of what happens when that old spirit sits in a bottle for a generation or two.

“If there’s a primary thread to these old spirits and cocktails,” said Jacob Briars, director of trade advocacy for Bacardi, who has sampled his share of aged libations, “it’s that each of them has become more round. There is a softness. The sharp, bright notes have faded over time, and instead you have this wonderful integration of all the flavors.”

Troy Sidle, the partner at Pouring Ribbons who oversees the Chartreuse collection, has grown philosophical about the differing flavor profiles he finds in various bottles of the classic liqueur. “Chartreuse is always the same,” he said. “What changes is the expression of it. Chartreuse is really the collection of 130 herbs and spices, not so much the product sold that is the combination of all those flavors.”

These bars acquire their bottles, for the most part, through private collectors. The Experimental Cocktail Club drew its stock from two or three collections. Vintry’s whiskered whiskeys come from Harry Poulakakos, who used to own Harry’s at Hanover Square and began buying old whiskeys and brandies in the 1960s. “Once in a while Harry invites me to his cellar and says, ‘Maybe you see something else you like,’ ” said Ivan Mitankin, a partner at Vintry.

The private collector Pouring Ribbons tapped was Mr. Sidle himself, who has an abiding interest in Chartreuse. He came upon a few of his acquisitions in curious ways. He spotted bottles of 1980s yellow and green Chartreuse in a liquor store on Avenue C, where they had been gathering dust. “They clearly didn’t know what they had,” Mr. Sidle said.