Studies on Rhythmic Precipitates

Abstract

(1) The conditions of the formation of various examples of rhythmic precipitates have been studied. The effects were tested of the change of species and concentrations of gel, inner electrolyte and outer electrolyte, the temperature, the light intensity and the hydrogen ion concentrations of medium and outer electrolyte solution.(2) The regularity of spacing between bands has been studied. The distance between bands is expressed empirically by the quadratic equation concerning the ordinal number of it. The same equation was deduced from a theoretical standpoint, the physical meaning of the equation being considered.(3) Classification of the rhythmic precipitates by the cause of formation and by the structure has been proposed. Secondary bands were investigated and discussed.(4) New examples of rhythmic precipitate have been described, i.e. barium chromate, cobalt phosphate, lead carbonate, lead phosphate, lead iodate, silver arsenate, silver carbonate, silver iodate and silver capronate in gelatine gel, and bismuth chromate, bismuthyl chloride, bismuthyl nitrate, cobalt phosphate, cobalt sulphide, copper carbonate, copper iodate, cerium iodate, calcium phosphate, calcium oxalate, strontium oxalate, ferric ferrocyanide, lead carbonate, lead iodate, lead phosphate, nickel dimeihylglyoxime, silver arsenate, silver ferrocyanide, silver phosphate, silver iodate, uranyl phosphate and uranyl arsenate in silicic acid gel. The conditions for the formation of these rhythmic precipitates have been thoroughly investigated.