Environmentally friendly, biodegradable source of potassium ion. Prepn: E. Groschuff, Ber. 36, 1783 (1903); and complex formation with formic acid: J. Kendall, H. Adler, J. Am. Chem. Soc. 43, 1470 (1921). Crystal structure: B. F. Mentzen, Y. Oddon, Inorg. Chim. Acta 43, 237 (1980); J. W. Bats, H. Fuess, Acta Crystallogr. B36, 1940 (1980). Properties and applications as a secondary refrigerant: A. Aittom"aki, A. Lahti, Int. J. Refrig. 20, 276 (1997).