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.).
6.1. Doe in de Kjeldahlkolf (5.1) kooksteentjes (5.2) (b.v. 3 glas-parels), 15 g kaliumsulfaat (4.1), 1,0 ml kopersulfaatoplossing (4.2), ongeveer 5 g melkmonster (tot op 0,001 g nauwkeurig afgewogen) en 25 ml zwavelzuur (4.3).