Division 5.4 Determination

Heat the dish with its contents on a low flame, a hot plate or an I/R lamp until the test portion is completely charred, taking care that it does not burst into flame.

Transfer the dish to the electrical furnace (4.3), controlled at 825 ^oC ± 25 ^oC, and heat for at least one hour until all carbon has disappeared from the dish. Allow the dish to cool somewhat and then place in the desiccator (4.4) to the temperature of the balance room and weigh to the nearest 0,1 mg.

Repeat the operations of heating for approximately 30 minutes, in the electrical furnace (4.3), cooling and weighing, until the mass remains constant to within 1 mg or begins to increase. Record the minimum mass.