It used to be that barrel-aged gin wasn’t a novelty or a niche segment of the market; instead, it was the norm. During the first half of the 19th century, all gins were aged out of necessity—wooden barrels were the only way that the spirit could be transported from the distillery to the tavern. After 1850, however, metal tanks replaced wooden barrels as the gin transportation container of choice. Slightly aged gins didn’t completely die off, but finding a bottle of “yellow gin,” as the aged spirit was known, b…