Bruise and pound the ginger well, and put it into a bowl with the boiling water. Add the juice of a lemon and the well-grated zest. Add the cream of tartar and the sugar, mixing and stirring constantly. When it is luke warm add the yeast, dissolved in a little water. Mix well and cover tightly, and let it stand for six hours. Then strain it and put it into bottles with patent tops, and keep in a cool place. It effervesces rapidly if not kept most securely corked.