Calcium sulfate an unusual property: when mixed with water at normal (ambient) temperatures, it quickly reverts chemically to the preferred dihydrate form, while physically "setting" to form a rigid and relatively strong gypsum crystal lattice: This reaction is exothermic and is responsible for the ease with which gypsum can be cast into various shapes including sheets (for drywall), sticks (for blackboard chalk), and molds (to immobilize broken bones, or for metal casting). Mixed with polymers, it has been used as a bone repair cement. Small amounts of calcined gypsum are added to earth to create strong structures directly from cast earth, an
The Chalk Garden " 'The Chalk Garden' is extraordinarily modern for a high comedy set in the drawing room of a stuffy Sussex manor house: its plot and structure are elliptical; its witty lines aren't brittle but are instead redolent with what the author calls 'the shape and shadow of life.'... Bagnold's play is in part a journey to the bottom of Miss Madrigal's identity; it is also about the effect the woman has on her employer's household. Mrs. St. Maugham is a selfish, eccentric paragon of privilege who spends her days gardening but can't make anything grow." The Chalk Garden The Chalk