jellies, boil them rapidly until they are well reduced, _before_ the
sugar is added, and quickly afterwards, but do not allow them to become
so much thickened that the sugar will not dissolve in them easily, and
throw up its scum. In some seasons, the juice is so much richer than in
others, that this effect takes place almost before one is aware of it;
but the drop which adheres to the skimmer when it is held up, will show
the state it has reached.