A WET COMBUSTION METHOD FOR DETERMINING TOTAL CARBON IN SOILS

Abstract

A wet combustion method is described by which the total C in soils and in pure organic compounds can be detd. in 20 to 25 min. with a high degree of accuracy. Oxidation of the C is accomplished by K2Cr207 in a mixture of H2SO4 and H3PO4. Speed of oxidation is increased by addition of H2O2. The CO2 set free is measured by collecting it in an evacuated absorption flask containing Ba(OH)2 and by titrating the excess Ba(OH)2 with HC1. A glycerine solution replaces mercury as the confining liquid for the CO2. KI dissolved in the glycerine soln. prevents the apparent increase in CO2 when chlorides are present. Results are low, however, if the chloride content is > 1%. Carbonates are removed by boiling in a soln. of 5% H2SO4 with 5%) FeSO4, apparently without loss of organic C.