OK, I was wrong and had to go relearn my HS chemistry. The formula weight for potassium carbonate in crystal form is for two units of carbonate. Worked out correctly, the ratio between anhydrous and crystalline is 0.836, so you use 62.73 grams of anhydrous, rather than the 75 grams of crystalline that the FX-2 formula specifies. This is almost exactly the 17% rule that applies to sodium carbonate as well. Ain't book lernin fun?

-- Conrad Hoffman (choffman@rpa.net), February 05, 2002