Wash the measuring cylinder and then add about 25 cm3
of 2 mol dm−3
ammonia solution to it.
Slowly add the ammonia solution to the evaporating basin, stirring the solution as you do so.
After you have added about 15 cm3
check with indicator paper to see if the pH has reached 7.
Add further 1 cm3
amounts of ammonia solution if necessary, checking the pH after each
addition, until the pH is 7 or above