Lactic Acid: Milk, Milk Sugar and Chalk Fermented a Month (Wackenroder, US Dispensatory 1907)

Wackenroder's lactic acid: skimmed milk, milk sugar, chalk and water kept warm for a month. As the acid forms, the chalk takes it up as calcium lactate. That salt is crystallised and then split with exactly enough sulphuric acid to free the lactic acid. Source: The Dispensatory of the United States of America (1907), Acidum Lacticum. Pharmacopoeial lactic acid, used as food-grade, as ruled. Unknown: how the free acid is separated afterwards; the Dispensatory does not say, so it is linked to an unknown head. Sulphuric acid is a strong acid. Picture drawn by Youblob.