The potassium hydroxide or potassium chloride has to be melted at a very high temperature .
Potassium salts are also available in tablets or capsules , which for therapeutic purposes are formulated to allow potassium to leach slowly out of a matrix , as very high concentrations of potassium ion ( which might occur next to a solid tablet of potassium chloride ) can kill tissue , and cause injury to the gastric or intestinal mucosa . For this reason , non-prescription supplement potassium pills are limited by law in the U.S. to only 99 mg of potassium .