Also known as “gum arabic” this powder is often sold as a natural source of dietary soluble fiber. It has traditionally been used as a thickener and a syrup stabilizer because it helps prevent sugar crystallization. You can make “simple” syrup, but the reason it is simple is because it is missing the gum. Use a few spoonfuls of this stuff and you can make historic, thick gum syrup (gomme sirop) which lends a wonderful mouthfeel to your Old Fashioned or any cocktail.
You definitely want food-safe gum arabic poweder, otherwise, you might end up with big chunks of sap and tree bark that are difficult to break apart use effectively in cocktails.