“…Various electrically monitored titrations involving silver nitrate are relatively less convenient, especially on a large scale (Laitinen, 1946;Mokady, 1968). Another group of methods includes colorimetry and photometry (Kolthoff, 1951;Kuroda, 1950;Menis, 1957;Peck, 1959;Rodabaugh, 1972;Siggia, 1947 (Bazelle, 1971;Black, 1960;Buchanan, 1968;I Chanin, 1954;Clarke, 1950;Coetzee, 1969;Haynes, 1972;James, 1972;Mascini, 1969;Mattock, 1962;Rechnies, 1966;Van Loon, 1968).…”