Is contamination purified through transformation (istihalah)?

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The apparent position of the Madhhab is that no impurity is purified through transformation (istihalah), with the sole exception of khamr (intoxicant) that transforms into vinegar by itself. All other transformations do not result in purification, such as impurities turning into ash upon burning, a pig becoming salt after falling into brine, smoke arising from burning impurity, or condensation dripping from vaporized impure water onto a smooth surface. Transformation of all impurities is derivable by analogy (Qiyas) from the transformation of khamr into vinegar and the tanning of animal hides, and the purification of animals designated for consumption (Jallalah) through confinement. The first statement represents the apparent position of the Madhhab. Furthermore, the Imam (our master) forbade baking bread in an oven previously used for cooking pork.