Jim Shields, if you don't mind, let's continue the inorganic chemistry lesson. If, as you say, potash is literally the potassium containing residue of burned wood, are there such things as sulfate of potash and muriate of potash? And if so, are they different in some way from potassium sulfate and potassium chloride? I'm not asking you if the names exist - we already know that these terms are common, at least in the older gardening literature. I'm asking if there is such a thing as sulfate of potash which is distinct from potassium sulfate and a muriate of potash which is distinct from potassium chloride. For instance, is it ever correct to use the terms sulfate of potash and muriate of potash to name fertilizers? Are these names vestiges of older processes which began with potash in the literal sense to produce crude, unrefined potassium sulfate or potassium chloride? If so, what should I be asking for to purchase the crude, unrefined potassium sulfate? In addition to that, there is this. I did a little bit of homework before I went potassium shopping. I discovered what to me is a bizarre anomaly: retail gardening products are sold on the basis of potassium oxide percentage. What makes that bizarre to me is that such products do not contain potassium oxide (or do they?). Is the idea that you are buying something which is the equivalent of a raw potassium source which would yield so much potassium oxide upon burning? Curiously (to my sensibilities at least) the potassium oxide "content" on the retail products is in big print; you have to read the fine print to find out what the real source of the potassium is. Help me out here! Jim McKenney