I just finished several experiments using sodium carbonate (wash soda) and potassium carbonate (potash). These are the original alkilis used in saponification from the days before hydroxides. Potassium carbonate was derived from wood ashes, sodium carbonate from burning seaweed. I got potassium carbonate from a chemical supplier and the sodium carbonate as Arm & Hammer wash soda. I'm confident in the potassiums purity but I don't know the purity of the wash soda. Hey, it's what I had... The first portion of the experiments was to get an idea as to there strengths compared to hydroxides. I did this via titration (pronounced ty-tray-shun). This is a test done by adding alkili and acid in the presence of a PH indicator. I used phenolpthalein as the indicator and vinegar (standard 5% acidity) as the acid in my first tests. Basically the question is how much vinegar does it take to nutralize 1 gram of lye (NaOH), caustic potash (KOH), wash soda (sodium carbonate, Na2CO3) and potash (sodium carbonate, K2CO3). The more vinegar it takes, the stronger the alkili must be. Here are the results... NaOH (lye) = 29ml vinegar KOH (caustic potash) = 20ml vinegar Sodium Carbonate (wash soda) = 10.5ml vinegar Potassium Carbonate (potash) = 9ml vinegar I also tested borax while I was at it, it took 3.5 - 3.75ml vinegar. Now that I had an idea as to strength, it was time to work on saponification values. I work mostly with soybean oil so I used it's sap values which are .136 for NaOH and .19 for KOH. For 1 pound of oil, this equals 61.6g NaOH & 86 KOH. To minimize how much chemistry I needed, I divided by 10 to get 6.1g and 8.6g. Nuetralization of fatty acids is slow and requires a lot of effort. To speed up the process I determined how much sulfuric acid was needed to nuetralize the saponification value of 6.1g NaOH and 8.6g KOH. Both required approximately 4.5ml of 93% sulfuric acid. Therefore 4.5ml of sulfuric acid is a convenient substitute for 1/10 the saponication value of 1 pound of soybean oil. To nuetralize the 4.5ml of acid took 8g potassium carbonate and 7.5 grams sodium carbonate. Therefore it should take approximately 80g potassium to saponify 1 pound soy and 75g sodium. BTW, there are 28g in an ounce. Next I cooked each in a double boiler.... but nothing happened. After an hour I poured the potassium into a pot and cooked it. It's boiling temp was 230*F. It did saponify but not fully, I'm assuming I needed more. Unlike KOH, at no point did it ever thicken, it always stayed thin and watery. The sodium stayed in the double boiler for 2 hours with often stirring. There was no change and the next day it had separated. Next I tried using equal parts potassium, oil and water. I got some soap curdles, maybe about 1/2 of the oil saponified but it was very slow, even at 230*F. As the water boiled off, the potassium fell out ot the bottom in a sand-like form. Adding water put the potassium back into solution. After about 1.5 hours I got tired and added sap value of KOH. This got it going but it still stayed very thin. After cooling however, it did get thick and eventually semi-solid. Lather was surprisingly good.