Division 6.1 To the Kjeldahl flask (5.1.) add boiling aid (5.2.) (eg. three glass beads), 15 g of potassium sulphate (4.1.), 1,0 ml of copper sulphate solution (4.2.), approximately 5 g of milk sample (weighed to the nearest 0,001 g) and 25 ml of sulphuric acid (4.3.). Use the acid to wash down any copper sulphate solution, potassium sulphate or milk on the neck of the flask, and gently mix the contents of the flask.
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