This section is from the book "Three Meals A Day", by Maud C. Cooke. Also available from Amazon: Three Meals a Day.
4 bars yellow soap, shaved fine; 2 pounds sal-soda, 6 ounces borax, 2 ounces liquid ammonia. Put the soap in 8 quarts of soft water to dissolve. If the water is hard, break it first. When the soap is nearly dissolved over the fire add the borax and sal-soda. Stir until all is melted. Pour into a large tub, or shallow pan. When partly cool add the ammonia slowly, mixing well. Let stand a day or two and then cut into cakes or bars. Do this in a warm place. No better soap can be found for all kinds of washing, and the outlay can be covered by three cents per pound. This recipe has often been sold for five dollars.
1 pound concentrated potash dissolved in 2 quarts of boiling water. Let stand until luke-warm, then pour into the lye 5 pounds of clean grease also luke-warm; stir twenty minutes, and, while stirring, pour in gradually 3 ounces of ammonia. When cold cut in bars., It is best to let it cool in something broad and shallow. This is very convenient to make when a quantity of grease has accumulated. It should be tried out before putting into the lye.
Ashes should be from good wood, or the lye will be weak. Keep the ashes dry until a week before using; see that they are well packed down in the leach, which can be made out of a barrel. Then pour on water until the lye begins to drip slightly; leave it to soak out the strength of the ashes for a week. Then pour on water and begin to run off lye. The proper strength can be told by its floating a fresh egg. If it is not strong boil it, or turn it back through the ashes again. Then add clear grease, or "soap-grease" in the proportion of 1 pound to 1 gallon of lye, boil until it is dissolved, then dip in a feather and if, on taking out, the plume part can be stripped off with the fingers, it requires more grease, which should be added until it will take no more. If a white scum rises skim off (it is grease), or add a little more lye. Boil until it looks soapy. If the lye remains weak, on account of poor ashes, add potash until it is of sufficient strength.
5 pounds of potash in 5 gallons warm, soft water. Let dissolve over night. In the morning put over with 1 pounds of grease and boil until it is thick and soapy. If the lye needs more grease add it, test with a feather. If there is too much grease, which can be told by a scum rising, add a little more lye. Pour all in a keg, or half barrel, and add sufficient soft water to make it the proper consistency. It is much easier to boil a small quantity and thin afterwards.
The grease for this should be tried out. Do this gradually as scraps accumulate; pour the grease, a little at a time, into a kettle kept for the purpose. Tallow and lard scraps, after the clear fat has been pressed out, are put in water and boiled, then strained through a colander, the grease left to rise, removed in a cake from the surface of the water, boiled up and poured hot into the soap-grease kettle. Working in this manner makes a solid mass of pure grease that never molds. Twenty-five pounds of grease will make a barrel of soap. Fill the barrel half full of lye strong enough to bear up an egg. Heat the grease boiling hot and pour into the lye. Stir often, and when it begins to thicken, fill up with weak lye. If made in cold weather, heat the lye as well as the grease. It never fails to thicken, and is much whiter and cleaner than boiled soap. In warm weather the soap may be made by putting the cold grease directly into the cold lye and leaving in the sun; stir often.
 
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