Having some trouble interpreting 1800's recipes in "The Bon-Vivant's Companion" (1862).

I'd like to try some of the recipes for cordials, etc. (scaled down of course -- I don't think I need 10 gallons of any of these!), but I keep coming across a unit called "do." Does anybody know what that would be in modern ounces (or milliliters?)See page 107 of The Bon-Vivant's Companion.Thanks in advance, and enjoy!