Division 6.4 Determination

Using the pipette (5.2), add to the dish (A) exactly 5 ml of the magnesium acetate solution (4.1) so as to wet all of the test portion, and allow to stand for 20 minutes.

To the other prepared dish (B), add with the pipette (5.2) exactly 5 ml of the magnesium acetate solution (4.1).

Evaporate the contents of both dishes (A and B) to dryness on the boiling water bath (5.6).

Place both dishes in the oven (5.4), controlled at 102 ^oC ± 1 ^oC, for 30 minutes.

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

Transfer both dishes (A and B) to the electrical furnace (5.5), controlled at 825 ^oC ± 25 ^oC, and heat for at least one hour until all carbon has disappeared from dish A. Allow both dishes to cool somewhat and then place in the desiccator (5.7) 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 (5.5), cooling and weighing, until the mass remains constant to within 1 mg or begins to increase. Record the minimum mass.