Prepn: DE 285259 (1914 to Osterr. Ver. Chem. Metallurg. Prod.), Frdl. 12, 97; and physicochemical props: T. R. Narayanan Kutty, A. R. Vasudeva Murthy, Indian J. Technol. 10, 305 (1972). Crystal structure: S. Harkema, D. Feil, Acta Crystallogr. B25, 589 (1969). Use to solubilize mineral phosphates in soils: D. N. Pathak, Fert. Technol. 15, 154 (1978). Use for nitration of aromatic amines: T. P. Sura et al., Synth. Commun. 18, 2161 (1988).