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Egg Phosphate Syrup (Extract Vanilla drams Lemon)
Extract Vanilla, 2 drams; Lemon Syrup, 2 pints; Orange Syrup, 1 pint; Jamaica Rum, 6 drams; Acid Phosphate, 4 drams; Sherry Wine, 2 ounces. Mix.
This is a fountain bottling formula, not a finished drink: it makes a flavoring syrup that is drawn by the ounce, shaken with a whole egg, and topped with carbonated water. Everything here is measured in apothecary fluid units, which is the first thing to sort out.
- Drams and ouncesA fluid dram is 1/8 fluid ounce, about 3.7 mL. So 2 drams vanilla is roughly 1 1/2 teaspoons, 6 drams rum about 3/4 fl oz, 4 drams acid phosphate about 1/2 fl oz, and the sherry 2 fl oz. If the vanilla was meant by weight the difference is small enough not to matter.
- Acid phosphate is the hingeThis is dilute phosphoric acid buffered with calcium, magnesium and potassium salts "the sour" that gives phosphates their dry, mineral bite rather than a citric tang. It is still manufactured for bartenders. Do not substitute food-grade phosphoric acid concentrate, which is many times stronger, or citric acid, which tastes nothing like it.
- Lemon and orange syrupPeriod fountain syrups, not modern squash or cordial: roughly a heavy simple syrup (about 2 parts sugar to 1 water by weight) flavored with citrus juice and a little oil or extract. Commercial lemonade concentrate will read as far more tart and much less sweet.
- Jamaica rumCalled for as a flavoring, in a quantity too small to intoxicate anyone. A dark pot-still Jamaican rum has the funky, high-ester character the formula wants; a light white rum contributes almost nothing at this dose.
- YieldAbout 3 1/4 pints of syrup. At the customary 1 to 1 1/2 fluid ounces per glass, that is roughly 35 to 50 drinks, so scale down to a quarter batch unless you are serving a crowd. Bottle it and keep it cold; the sugar concentration and acid make it keep for weeks refrigerated.
- The egg the name promisesThe formula itself lists no egg; only the title implies that this syrup was drawn for egg phosphates, with a raw egg cracked into the shaker. If you build the drink that way, use a pasteurized egg in the shell or pasteurized whole egg, since nothing in the glass is ever heated.
- CarbonationFountain water was drawn under pressure into the syrup and was generally well charged. Use the coldest, most aggressively carbonated water you have and pour down the side of the glass; a flat phosphate tastes only of sugar.
The phosphate was one of the workhorses of the American soda fountain from the 1870s onward, fading later as bottled soft drinks took over the trade. Its defining ingredient, acid phosphate, is generally traced to the Rumford Chemical Works of Rhode Island and the phosphate chemistry of Eben Norton Horsford, and it was sold to druggists as much for its supposed tonic value as for its flavor, in a period when the soda counter sat at the back of the pharmacy and its drinks were understood as mild medicine. The egg phosphate belonged to the "nourishing" end of that menu, alongside egg lemonades and milk shakes, marketed to customers who wanted something restorative in the middle of the day. That a fountain manual gives you a pre-mixed syrup rather than a drink recipe tells you how the trade worked: the operator compounded gallons in the back room so that the man at the marble counter could turn out a glass in under a minute.