METHOD FOR PRODUCING FERROMAGNETIC LIQUID Russian patent published in 1998 - IPC

FIELD: measuring systems. SUBSTANCE: magnetite is settled down, sediment is treated with aqueous solution of acetic acid while heating and stirring it, magnetite is stabilized with surface-active substance in acetic acid solution. Sediment is subjected to thermostatic control and coagulation, mother liquor is decanted, and stabilized magnetite is rinsed with distilled water. Rinsing is conducted until Fe³⁺ ions are fully eliminated with respect to qualitative reaction with ammonium rhodonite. EFFECT: high fluidity of liquid obtained at low temperatures and in extended temperature range, high transient speed in measuring instruments, such inclinometer, etc. 5 cl, 1 tbl, 1 ex