I’m sure you have seen a movie in which they ordered a phosphate soda. You might have even been so lucky to see one on a menu at a local restaurant. I had that same luck this weekend at the Courier Cafe in Champaign, IL. The restaurant is in my father’s home town and is the location of the old newspaper. The same newspaper that he was a paperboy from. When we went inside, he pointed out how it changed and walked through his morning routine when he was a kid.
Phosphate sodas were the predecessor to milkshakes. They were a combination of soda water, phosphoric acid and flavoring. This was most likely fruit syrup but could even be booze. There is a trend now to bring this back and mixologists are experimenting with it. It is a sour flavor similar to citric acid (lemon/lime juice). Try replacing it with citrus in your next cocktail for a neutral but sour flavor. You can purchase it from The Boston Shaker.
Check out Art of Drink for a recipe on Cherry Phosphate.