E. Cobham Brewer 18101897. Dictionary of Phrase and Fable. 1898.
Livy tells us that when Hannibal led his army over the Alps to enter Rome he used vinegar to dissolve the snow, and make the march less slippery. Of course this tradition is fabulous. Where did the vinegar come from? Nepos has left a short memoir of Hannibal, but says nothing about the vinegar. (Livy, B.C. 59 to A.D. 17; Nepos about the same time; Hannibal, B.C. 247183.)