Analysis of mortar by wet chemistry, XRD, AAS, DTA, and petrographic microscopy served to solve four problems: a wall that bowed and fell down contained unslaked quicklime in its mortar; light rains infiltrated a brick wall because mortar had been placed during a winter freeze and capillaries had been left by melted long slender crystals of ice; efflorescence on and spalling of a multi-walled two-story brick building and corrosion of its galvinized anchors resulted from inclusions of calcium chloride up to 2per thousand of its Portland cement content in an otherwise correct formula; travertine panels were displaced and cracked because a white powder, apparently plaster-of-paris, had been added to the mortar to speed setting. -- CAL