This is the first of a series of specifications for the lime used in various chemical industries. To assist in the development of these specifications, the Bureau of Standards has 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 and Forest Service of the Department of Agriculture; and the Nitrates Division of the War Department. The present specification, based on a draft originally prepared by F.A. Curtis, chief of the paper section, Bureau of Standards, has been unanimously approved by the above conference, and has also received the formal approval of the National Lime Association and the Technical Association of the Pulp and Paper Industry.