Pick over and hull the raspberries. Dissolve sugar in vinegar and pour mixture over fruit. Stir and mix well with wooden spoon. Strain after 2 days, pressing out all the liquid possible. Put the pulp into a bowl and cover with its own bulk of boiling water. Stir and let stand until cold. Squeeze as dry as possible through a linen cloth and mix with the vinegar liquid. Add the yeast, 2 level tablespoons to each gallon. Allow to ferment, and when fermentation stops, bottle. Store in a cool place for at least 2 months before using.