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Phosphated Sherbet
Diluted Phosphoric Acid, 2 ounces; Citric Acid, 2 ounces; Granulated Sugar, 10 lbs.; Sherry Wine, 1 gallon; Pure Water, 9 gallons. Mix and charge to 150 pounds. Dose, 6 ounces every half hour. Get your fountain ready each day before the first customer arrives.
This is a bulk soda-fountain formula, not a domestic recipe: it makes ten gallons of acidulated sherry sherbet to be drawn from a charged fountain. Scaling it down and understanding the two acids are the whole job.
- What "diluted phosphoric acid" meansIt is the pharmacy preparation, roughly 10 percent phosphoric acid in water, not the concentrated 75-85 percent product sold for descaling or as a food-grade concentrate. Substituting concentrate ounce for ounce multiplies the acid roughly eightfold. The modern equivalent sold to bartenders is acid phosphate, a phosphoric acid solution buffered with calcium and magnesium salts, used a dash at a time -- on the order of a quarter-teaspoon per drink.
- Weight or volumeThe citric acid is plainly 2 ounces by weight. The phosphoric acid, being a liquid, is almost certainly 2 fluid ounces. The original does not say, and the two are close enough here that it does not much matter at this dilution.
- "Charge to 150 pounds"That is the carbonating pressure of the fountain's apparatus, not a quantity of anything. No home carbonation equipment operates anywhere near 150 psi, and antique fountain hardware should not be pressed into service. To make this at domestic scale, carbonate chilled water separately and combine, or accept a still drink.
- "Dose, 6 ounces"Soda books borrowed pharmacy language, the counter often standing in a druggist's shop; here it appears to mean simply a six-ounce glass. Whether the half-hour interval was meant as real posology or as selling language is not clear from the text.
- Sherry, and how much alcohol resultsOne gallon of fortified sherry in ten gallons of finished drink gives roughly 1.5 to 2 percent alcohol by volume, so a six-ounce glass carries something like a quarter of the alcohol in a light beer. Use a drinkable amontillado or oloroso; salted cooking sherry will ruin the balance.
- SweetnessTen pounds of sugar in ten gallons is about 11 percent by weight, close to modern soda. Dissolve it in a portion of warm water as a syrup first and cool completely before adding the acids and wine.
- Yield and scalingTen gallons is roughly 210 six-ounce servings. A tenth batch is about 3½ quarts water plus 1.6 cups sherry, 1 lb sugar, and roughly 1¼ teaspoons each of the two acids by the original proportions; taste before committing.
- StorageNothing here is perishable in the bacterial sense, but the sherry oxidises. Made stock should be kept cold, stoppered, and used within a few days.
"Sherbet" here descends, through Turkish and Persian, from the Arabic sharbat, a sweetened acidulated drink, and by the late nineteenth century the American soda counter used the word loosely for any tart fruit-or-wine cooler rather than the frozen ice it now denotes. The phosphate style is the more interesting half of the name: druggists dispensed diluted phosphoric acid as a tonic and digestive, and it migrated to the fountain because it gives a clean, drying sourness quite unlike citric acid's bright bite, which is why the formula uses both. Fountains were fixtures of drugstores because the same proprietor already had the acids, the syrups, the scales and the license, and the run of phosphates, cherry, lemon, orange, chocolate, and wine varieties like this one, is often said to have flourished from the 1880s onward, though phosphates ran well into the 1920s and beyond. A sherry sherbet sat awkwardly in that world even then, and recipes of the kind became harder to place once Prohibition arrived.