Liquid Petrolatum: The 330–390 °C Cut, Acid- and Soda-Washed, Filtered Through Charcoal

Liquid petrolatum (liquid paraffin) is the clear, tasteless oil the 1907 US Dispensatory describes: the heavy part of petroleum, distilled, washed with sulphuric acid and caustic soda, filtered hot through animal charcoal and redistilled. It was used in medicine, also taken by mouth. It is not today's food-grade mineral oil, which must also pass a later test for aromatic compounds. The source gives no quantities for the acid, soda or charcoal, so none are given here. The picture: a bottle of USP heavy mineral oil (F.B. Chamberlain Co., Wikimedia Commons, public domain).