The fight against food adulteration

Some of the commonly used additives in the 19th century were poisonous. To whiten bread, for example, bakers sometimes added alum (K₂SO₄.Al₂(SO₄)₃.24H₂O) and chalk to the flour, while mashed potatoes, plaster of Paris (calcium sulfate), pipe clay and even sawdust could be added to increase the weight of their loaves. Rye flour or dried powdered beans could be used to replace wheat flour and the sour taste of stale flour could be disguised with ammonium carbonate. Brewers too, often added mixtures of bitter substances, some containing poisons like strychnine, to 'improve' the taste of the beer and save on the cost of hops. By the beginning of the 19th century the use of such substances in manufactured foods and drinks was so common that town dwellers had begun to develop a taste for adulterated foods and drinks; white bread and bitter beer were in great demand.