It is difficult to ascertain from the literature1 exactly what are the optimum conditions for the air activation of charcoal, or exactly what happens during the processes of activation. Attempts at activation in a current of air are easily frustrated by a lack of attention to detail or to conditions in different parts of the mass of the charcoal. Similarly, so numerous are the factors involved that occasionally an exceptional success is achieved which it may prove impossible to duplicate.The present studies have been carried out over a series of many years, first with charcoal derived from redwood (Sequoia Sempervirens), as studied by Dr. F. Carlyle Harmon, and then by one of us (R.F.S.) with sugar charcoal, which is practically the only source of highly active, ash-free