The organic material for iodin analysis is dried, mixed with and covered with CaO to render it alkaline and reduce the rate of combustion, and burned in pure oxygen in a large combustion tube with the end narrowed and bent downward for about 50 cm. The first third of this narrowed portion is covered with a thin layer of asbestos fibers to protect it from a lead coil through which cold water runs. The middle third is water-jacketed. The lower third dips into an absorbing apparatus filled with NaOH solution. The greater the amount of CaO mixed with the unknown material, the greater amount of iodin remains in the ash. The alkaline solution from the absorption apparatus is evaporated to 10 c.c. after adding to it the rinsings of the combustion tube. The ash is ground with water or the solution from the absorption apparatus in a ball mill and the extract is evaporated to 10 c.c. The solution is acidified until PH = 1 and placed in a 12 c.c. separatory funnel and 0.1 c.c. of 0.1 N arsenius acid added, and allow...