The conventional factor 1.724 in the equation, carbon X 1.724 = organic matter, is too low for the humus horizons of forest soil. It is necessary to recognize the stage of decomposition of the material in question. The factors proposed are: for freshly fallen leaves or litter, 1.89; for the partially decomposed "F" or fermentation layer, 1.85; and for the well decomposed, structureless "H" or humification layer, 1.80. These factors appear to be equally applicable to the several different forest types usually recognized in New England.