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Gypsum plaster, [12] also known as plaster of Paris, [13] is a white powder consisting of calcium sulfate hemihydrate. The natural form of the compound is the mineral bassanite . [ 14 ] [ 15 ]
With judicious heating, gypsum converts to the partially dehydrated mineral called bassanite or plaster of Paris. This material has the formula CaSO 4 ·( n H 2 O), where 0.5 ≤ n ≤ 0.8. [ 8 ] Temperatures between 100 and 150 °C (212–302 °F) are required to drive off the water within its structure.
The word gypsum is derived from the Greek word γύψος (gypsos), "plaster". [9] Because the quarries of the Montmartre district of Paris have long furnished burnt gypsum (calcined gypsum) used for various purposes, this dehydrated gypsum became known as plaster of Paris. Upon adding water, after a few dozen minutes, plaster of Paris becomes ...
One design has a thin layer of hardened plaster of Paris on the bottom to absorb the killing agent. The killing agent will then slowly evaporate, allowing the jar to be used many times before it needs to be refreshed. The absorbent plaster of Paris layer also helps prevent the agent sticking to and damaging insects.
A common casting medium, plaster is also a popular pick for making molds. Using this substance, which is manufactured in powder form, is ideal when you want a rigid structure to make casts as an ...
The plaster is modified with the addition of animal glues such as isinglass or hide glue. 'Marezzo scagliola' is worked with the pigmented batches of plaster in a liquid state and relies mainly on the use of Keene's cement, a unique gypsum plaster product in which plaster of Paris was steeped in alum or borate, then burned in a kiln and ground ...
Haussmann went to work immediately on the first phase of the renovation desired by Napoléon III: completing the grande croisée de Paris, a great cross in the centre of Paris that would permit easier communication from east to west along the rue de Rivoli and rue Saint-Antoine, and north-south communication along two new Boulevards, Strasbourg ...
The NFL playoff schedule is about to be set, with the wild-card dates and times for every matchup to be revealed during Week 18.