I found this recipe on liquor.com.

gin, lemon juice, simple syrup, egg white, soda water⁣
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This drink’s recipe first appeared in print in 1876, and became wildly popular in the US between 1900 and the 1940s. So popular in New Orleans, in fact, that extra bartenders had to be employed during Mardi Gras to do all the shaking required to get the egg white to foam. According to one writer in 1937 the bar staff “nearly shook their arms off, and were still unable to keep up with the demand.”⁣
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Making a Gin Fizz is an aerobic exercise. ⁣
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I knew I’d like this drink, because it’s basically a Tom Collins with foam. And as much work as it is to get this much foam, it’s nice…it makes the drink feel kind of special. ⁣