The juice of grapes is forbidden if it boils by itself or by fire or by the sun. If it does not become alcohol, its prohibition is gone. If it becomes alcohol, its prohibition can only be removed after it becomes vinegar. If grapes cook themselves and if it is known that their contents have been boiled, drinking the liquid is absolutely forbidden; otherwise it is not forbidden, just as what is called "grape juice" is not forbidden, even if it has been boiled, unless it becomes an intoxicant. Then it becomes forbidden until it turns to vinegar.