The French way of washing white linen
Take 2 vessels with a capacity of at least 7.5 liters, fill and heat 5 liters of water in each of them to boil. In a boiling water of one vessel drop 10 g of finely chopped soap, and in another vessel dissolve 3-5 potassium permanganate crystals: the color of the solution should be red, not purple. Mix both solutions: in this case, the liquid will take on a dark brown colloidal solution of manganese dioxide. Stir the hot mixture with a stick, causing a strong foaming, and immerse 2-3 pieces of linen in it. All stains and all types of dirt are removed from the tissues, if they are kept for 6-8 hours (left overnight) in this solution. The next day, wet clothes are taken out of the vessel, rinsed, dried and ironed. The use of blue is not required.
The described method of washing relieves from heavy physical labor, which is inevitably associated with washing clothes in the usual way. Underwear does not deteriorate.