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Foam for Soda Water Syrups
(See also Soda Foam.) Take of American Dry Soda Foam 4 ounces; place in a pint bottle and fill with water; place the bottle in hot water for several hours; when cold, strain through cloth, and allow to settle until it becomes clear. Decant; add 4 ounces of alcohol, and enough water to make it measure 1½ pints. This will never spoil. Never add foaming material to syrup until about to use it. Use ½ ounce to the gallon. Syrups flavored with beer extracts require none. Be careful not to use enough to taste. Soda water is a veritable luxury and, when proper materials are used and the drink is scientifically dispensed, there is nothing half so delicious. At all times use "American Whole" and "Crushed Fruits," " Concentrated Fruit Syrups," "Fruit Phosphates," "Fruit Floss," etc., as they are the very best that can be obtained.
This is not a drink but a working solution for the fountain: a concentrated foaming agent, diluted and preserved, to be dosed into finished syrups by the half-ounce. The instructions assume a supply-house product that no longer exists in the retail trade.
- What "Soda Foam" wasNineteenth- and early twentieth-century foam powders were commonly saponin extracts of quillaia (soap bark, also sold as Panama bark), sometimes cut with sugar, gum or dried egg albumen. "American Dry Soda Foam" appears to have been a proprietary pack of this kind sold to fountain operators, and is not obtainable now. Quillaia extract is still a permitted beverage foaming agent but is regulated with an upper limit on saponin content, so any substitution has to follow the supplier's stated dosage rather than this one.
- Ounces here are weight, then volumeThe 4 ounces of dry foam is weight; the 4 ounces of alcohol and the ½ ounce dose are fluid measures. A pint in an American fountain book is 16 fl oz, a gallon 128 fl oz.
- The alcoholFour fluid ounces of spirit in a finished pint and a half (24 fl oz) is about a sixth of the volume, roughly 16 percent by volume if the spirit was the strong grain alcohol of the period, which is what makes the claim "this will never spoil" plausible. The original meant plain grain alcohol; the finished solution is a preservative-strength tincture, not a drink.
- "Hot water for several hours"This is a water-bath extraction to pull the saponins out of the bark powder, not a boil. Keep the bottle standing in water held below simmer, loosely stoppered, and expect a cloudy brown liquor that clarifies only after long settling.
- Straining and decantingThe bark fines will not filter out through paper without clogging it. Cloth first, then let the bottle stand undisturbed for a day or more and pour the clear liquid off the sediment.
- The instruction that mattersFoam solution goes into syrup only just before service. The text gives no reason, but the likely one is that the foaming power does not survive long standing in sweet syrup; it is explicit that the dose must be small enough that nothing can be tasted. Saponins are bitter and soapy above a very low threshold.
- Dosage and yieldA pint and a half of solution is 24 fluid ounces, which at ½ fluid ounce per gallon treats roughly four dozen gallons of syrup. For a single gallon batch that is one tablespoon.
- Beer extractsRoot beer, birch beer and similar extracts of the period often drew on saponin-bearing barks and roots, which would account for their heading up on their own. The note reads as a caution against doubling the foaming agent.
Soda fountain foam existed because carbonated water alone throws a head that collapses in seconds, and a persistent creamy collar was what distinguished a well-dispensed glass from tap water with syrup in it. The agent behind it was saponin, the natural surfactant in quillaia bark, imported from Chile and South America and sold to the trade as soap bark, Panama bark or under proprietary names like the one here. Books of this kind were produced by or for the supply houses themselves, which is why the closing paragraph slides from instruction into a list of the publisher's own crushed fruits, phosphates and floss: the recipe and the catalogue were the same document. The claim that soda water is "a veritable luxury" is period-accurate rather than boastful, since a fountain in 1900 was an expensive fitted installation and the dispenser was expected to think of himself as a skilled operator working with graduated measures.