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 Boys Made Of? by Roud number What Are Little Boys Made Of? "What Are Little Boys Made Of?" is a popular nursery rhyme dating from the early 19th century. It has a Roud Folk Song Index number of 821. The author of the rhyme is uncertain, but may be English poet Robert Southey (1774–1843). Here is a representative modern version of the lyrics: <poem> What are little boys made of? What are little boys made of? That's what little boys are made of What are little girls made of? What are little girls made of? That's what little girls are made of</poem> The