Vanilla Syrup
Add one quarter of an ounce of vanilla extract to two quarts of plain syrup. Mix well and bottle.
A soda-fountain base rather than a finished drink: the whole thing depends on what the book means by "plain syrup."
- Plain syrupIn fountain and pharmacy usage this meant a heavy sugar syrup, much denser than a modern 1:1 simple syrup: the standard officinal syrup was close to 6 or 7 lb of sugar per gallon of finished syrup. The book does not define the term. A thinner syrup will make a weak, watery soda.
- A quarter ounce of extractAbout 1½ teaspoons, whether the author meant fluid ounces or weight; vanilla extract is close enough to water in density that the distinction does not matter here. That is a restrained hand for two quarts, so taste and add more if it reads flat.
- Mix wellExtract is alcohol-based and will float on cold heavy syrup if left alone. Stir or shake thoroughly, and shake the bottle again before each use.
- Bottling and keepingA true heavy syrup is self-preserving at room temperature for weeks because of its sugar concentration; a lighter syrup is not and belongs in the refrigerator, where it will keep about a month. Use clean bottles and discard at any sign of cloudiness or fermentation.
- Yield and useTwo quarts, which is a great deal. Fountain practice was about 1 to 1½ fl oz of syrup per glass topped with soda water, so this makes roughly 45 to 60 drinks; scale it down to a pint unless you are stocking a party.
- Beyond soda waterThe same syrup sweetens iced coffee, sweetens and flavours whipped cream, or goes over ice cream.
The flavoured syrup was the soda fountain's fundamental unit: a dispenser kept a row of them, and a drink was a measured pump of syrup plus carbonated water. Vanilla was a workhorse of that row, both as a flavour in its own right and behind chocolate and cream sodas. The recipe's brevity is the point -- it assumes the reader already has plain syrup to hand, the way a fountain clerk would.