suhe veekoguse, mille tellis imab pärast 24-tunnist külmas vees leotamist, ja veekoguse, mille see tellis imab pärast 5-tunnist keevas vees seismist, vahel, ratio between the amount of water a brick absorbs after soaking 24 hours in cold water and the amount of water it absorbs after it has been in boiling water for 5 hours