This is the ninth of a series of specifications for lime that is used in various chemical industries. To assist in the development of these specifications the Bureau as called together an Interdepartmental conference on chemical lime, composed of representatives of the Geological Survey and Bureau of Mines, of the Interior Department; the Bureau of Soils, Bureau of Chemistry, Forest Service, and Fixed Nitrogen Laboratory of the Department of Agriculture; and the Chemical Warfare Service, of the War Department. The present specification, based on a draft originally prepared by M. J. Proffitt, of the Polarimetry Section, Bureau of Standards, has been unanimously approved by the above conference, by the National Lime Association, and by the Hawaiian Sugar Planters Association.