Browne & Zerban (1948) quote Scheibler who in 1875 investigated a “double dilution” method to reduce the error caused by the lead precipitate in saccharimetry; Pellet & Sachs in 1880 […]
Sampling condensed vapours and condenser waters is never easy. Beale (1959, 1962) and Claire (1965, 1967) mention practical difficulties encountered. Vapour sampling involves iso-kinetic (constant velocity) principles which require sophisticated equipment to obtain representative condensed vapour samples. Most workers have sampled condensates and condenser waters, using simplified sampling equipment. One of the problems associated with condenser waters is that the inlet water usually contains sugar. The large volumes of water and low concentrations of sugar can cause serious errors. A simple calculation illustrates the difficulty; we assume that the condenser inlet and outlet waters contain 70ppm of sugar, that 1 ton of vapour requires 30 tons of inlet water, and that the analytical precision is ±1ppm.
An interesting aspect of milling is the evaluation of the performance of each mill in the tandem. Early (1921-1931) analytical techniques are described in Browne & Zerban (1948); sampling is discussed in the SASTA Laboratory Manual (1985). Material balances across milling tandems normally use 4 main assumptions which are not all rigorously correct:
Literature on the chemical cleaning of evaporators was available in 1929 (Spencer & Meade; 1948); in most cases sodium hydroxide and soda ash were boiled individually or as mixtures in the vessels which were then drained and washed. A boiling with hydrochloric acid would follow if necessary. Spraying techniques in Java and Hawaii were seen to be more economical in terms of chemical quantities. Fermented molasses was used in Queensland in the early 1930’s, and Honig (1953) quotes results obtained in 1949 from Taiwan.