The Kjeldahl bulb or Kjeldahl trap between the digestion flask (Kjeldahl flask) and the condenser improves distillation efficiency by preventing carryever of the alkaline digestion mixture and water vapours into the receiving flask and the large lower tube facilitates the return of any condensate to the digestion flask. The slightest bit of contaminated of the receiving solution can cause significant error in the titration step.The condensate in the bulb/trap is maintained above mathrm‌pH‌7 by the non-volatile alkali sucrubbed from the vapour and it is kept at or near the boiling point of passing steam. Under these conditions, no ammonia should be retained in the condensate of the Kjeldahl's trap.