Gum Syrup

Gum (or gomme) Syrup is basically a simple syrup with gum arabic added to create a smooth mouthfeel. Gum arabic is an emulsifier derived from hardened acacia tree sap. Going back to the 1830s, sweet almonds were included, but they were phased out by the time Jerry Thomas penned his famous Bar-Tenders Guide:  How to Mix Drinks in 1862.