Lactic Acid: Glucose Fermented over Chalk, Freed with Sulphuric Acid

Technical lactic acid is made by fermenting sugar. Thorpe's Dictionary (1912) gives McLauchan's method: glucose, chalk and a little malt in water, started with a spoonful of sour milk and kept at 45 °C for six days. The chalk keeps the liquid neutral so the bacteria keep working, and the acid collects as calcium lactate. As in the works, sulphuric acid then sets the lactic acid free: a colourless, sharp-tasting syrup. Joining the two is our choice. The picture: our diagram.