Even though phosphates were closely associated with the soda fountain, the ingredient acid phosphate did crossover to the saloon and made it into a number of cocktail books. The one cocktail that often shows up in these guides is the Angostura Phosphate. This drink was a pick-me-up used to cure hangovers, settle the stomach and clear the head. Many of these drinks haven’t been properly made for decades because one of the key ingredients–acid phosphate–has been missing. With a little research and a lot of lab work I’ve managed to bring this ingredient back to life, and so far I’m really impressed.
The original acid phosphate was manufactured by the Rumford Chemical Works and was called “Horsford’s Acid Phosphate”. During the heyday of the soda fountain, Horsford’s was synonymous with acid phosphate, even though many pharmacists made their own.
When people hear the phrase “acid phosphate” most automatically think it is phosphoric acid. This isn’t the case. Acid phosphate is a combination of phosphate mineral salts and phosphoric acid. The mineral salts partially neutralized the phosphoric acid when they are added. The pH after mixing is around 1.8 to 2.0 or about the same as fresh lime juice.
Warning: Do not attempt to use pure phosphoric acid as a substitute, it is too acidic and could cause bodily injury. Even a 10% solution of phosphoric acid still has a pH around 1.0. Since the pH scale is logarithmic, that means it is 10x as strong as a pH 2.0 solution.
The original Horsford’s method was to mix bone ash–which is mostly calcium phosphate–with sulphuric acid. The two ingredients reacted to form phosphoric acid and some phosphate salts (calcium, magnesium, potassium and sodium). For my test samples, I have avoided the bone ash method. Most bone ash is used in the pottery and ceramic industry, and very little is food grade. Depending on the source of the bones, they could contain undesirable elements like heavy metals. Instead, I’ve reproduced the acid phosphate using food grade chemicals most often used in nutraceuticals.
For more information on acid phosphate check out Fix the Pumps
The Angostura Phosphate combines four ingredients with impressive results. Lemon syrup plays a key role.
The lemon syrup is very “lemony” with the right balance of sweetness and provides a pleasant base flavour for the drink. The addition of lemon oil is what makes this an outstanding syrup.
Adding acid phosphate brings a pleasant dry astringency that tones down that citric acid “tang” from the lemon.
Like the Wild Cherry Phosphate, this is another soda fountain, and saloon, classic. Whether it helps a hangover or not is beyond the scope of this post, but as a classic drink, it definitely exceeded my expectations.