Scrape and cut up carrots and turnip. Slice the leek, and cut celery into dice. Shred the cabbage. Put into the jar with the water, and place in a moderate oven, or on the top of a closed range. If it is necessary to use a gas ring, turn very low and stand jar on an asbestos mat. Bring to the boil slowly and then simmer for 2 1/2 hours.