Grape Vinegar

From 1913:

Pulp the grapes, measure them, put them into a stone crock with a third as much good cider vinegar as there is pulp. Cover closely and leave for three days, stirring often; keep in a cool place. On the fourth day squeeze the pulp and vinegar; to every three quarts of the liquid allow five pounds of granulated sugar. Put over the fire, boil ten minutes, skimming frequently, and then bottle or can and seal closely. Use it in water for a drink in the proportion of a tablespoonful of the vinegar to glassful cold water.