Excerpt from The Fire-Resistive Properties of Various Building Materials This bulletin contains the results of tests of thirty panels of vari ous building materials, made by the United States Geological Survey with a furnace in the Underwriters' Laboratories, Chicago, Ill., to determine the effect of fire and subsequent quenching with water on mortar building blocks made of river and slag sands; common, hydraulic-pressed, and sand-lime brick; gravel, cinder, limestone, and granite concrete; glazed building and partition terra-cotta tile; and limestone, sandstone, granite, and marble building stone. The mor tar building blocks and the concrete were made in the structural materials testing laboratories; the other materials, except some of the common brick, were obtained in the Open market at Chicago, Ill.