This section is from the book "Monograph on Flavoring Extracts With Essences, Syrups, and Colorings", by Joseph Harrop . Also available from Amazon: Monograph On Flavoring Extracts With Essences, Syrups And Colorings.
May be made by adding the White of one (1) Egg to one (1) pint of Water, stirring well, and after standing for a short time, straining; or better, if it is not all to be used at once, adding to one-half (1/2) pint of Water, straining and adding equal quantity of syrup. The syrup tending to preserve it.
This can be used in the proportion of the White of one Egg to the gallon of Syrup, being one-half greater quantity than is usually recommended.