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
What Are Little Girls Made Of? What Are Little Girls Made Of? "What Are Little Girls Made Of?" is the seventh episode of the of the American science fiction television series, "". Written by Robert Bloch and directed by James Goldstone, it first aired on October 20, 1966. The first episode of the series to be repeated on NBC, the title of the episode is taken from the fourth line of the 19th-century nursery rhyme, "What Are Little Boys Made Of?." In the episode, Nurse Chapel searches for her long lost fiancé, and uncovers his secret plan for galactic conquest. On stardate 2712.4, the Federation starship