Estimation of pH Values. (Living Tissues and Saps.)

摘要: The outlook of this section is peculiar, because there already a vast literature dealing with theory, methods, and results; the basis theory practical methods results was officially admitted in 1950 to have been wrong. Therefore, all post-1950 work should be done some idea new limits placed upon accuracy results. Practically pre-1950 pH values were calculated on E 0 = 0.2458 V for saturated calomel electrode at 25° C. whereas standard value 0.2543 V, decrease 1.5 mV reference means that 0.03 0.04 must added order equate them which are themselves subject an accuracy-limit least ± 0.02. common- sense limit ordinary estimations first decimal place range 0.05 around recorded decimal. Greater can obtained when pure unmixed chemical substances used, but estimation not usually concerned substances, especially plant analyses.