Boil or steam the sweet potatoes until nearly cooked through. Peel the sweet potatoes and cut into thick slices. Add marmalades and orange juice, and toss to cover potatoes. Butter a casserole dish, make a layer with the potatoes, sprinkle light with salt, and dot with pats of butter, then bake in a 325 degree F oven for 30 to 40 minutes or until browned and candied.